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Yukihiro Tashiro Last modified date：2024.04.17

Associate Professor / Laboratory of Soil and Environmental Microbiology, Division of Systems Bioengineering, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University / Department of Bioscience and Biotechnology / Faculty of Agriculture


Papers
1. Kenji Sakai, Fandi Hidayat, Kazushi Maeda, Ai Sakake, Keisuke Fujishima, Maise Ojima, Kouta Jinya, Yukihiro Tashiro, Different traits for cold tolerance of extremely thermophilic Calditerricola strains isolated from mesothermal municipal sewage sludge and its hyperthermal compost, Journal of Bioscience and Bioengineering, doi.org/10.1016/j.jbiosc.2023.12.012, 137, 4, 290-297, 2024.04.
2. Mugihito Oshiro, Takeshi Zendo, Yukihiro Tashiro, Jiro Nakayama, Cyclic pairwise interaction representing a rock–paper–scissors game maintains the population of the vulnerable yeast Saccharomyces cerevisiae within a multispecies sourdough microbiome, Microbiology Spectrum, doi.org/10.1128/spectrum.01370-23, 11, 6, e0137023, 2023.12.
3. Tomonori Koga, Mitsuoki Ishizu, Kota Watanabe, Hirokuni Miyamoto, Mugihito Oshiro, Kenji Sakai, Yukiihro Tashiro, Dilution rates and their transition modes influence organic acid productivity and bacterial community structure on continuous meta-fermentation using complex microorganisms, Journal of Bioscience and Bioengineering, doi.org/10.1016/j.jbiosc.2023.08.004, 136, 5, 391-399, 2023.11.
4. Kota Watanabe, Azusa Yamada, Shunichi Nakayama, Toshimori Kadokura, Kenji Sakai, Yukihiro Tashiro, Distribution of bacterial community structures on human scalp hair shaft in relation to scalp sites, Bioscience, Biotechnology, and Biochemistry, doi.org/10.1093/bbb/zbad127, 87, 12, 1551-1558, 2023.09.
5. Azusa Yamada, Kota Watanabe, Yuri Nishi, Mugihito Oshiro, Yoshinori Katakura, Kenji Sakai, Yukihiro Tashiro, Scalp bacterial species influence SIRT1 and TERT expression in keratinocytes, Bioscience, Biotechnology, and Biochemistry, doi.org/10.1093/bbb/zbad122, 87, 11, 1364-1372, 2023.09.
6. Tao Zhao, 田代幸寛, Mohamed Ali Abdel-Rahman, Jiaming Tan, 花宮真美, 園元謙二, Efficient open integrated lactic acid fermentation of undetoxified semi-hydrolysate of rice straw using thermophilic Enterococcus faecium QU 50, Industrial Crops and Products, doi.org/10.1016/j.indcrop.2023.116494, 196, 116494, 2023.06.
7. Zhao Tao, 田代幸寛, 園元謙二, Construction and metabolic analysis of acetone-butanol-ethanol fermentation using mixed acetic acid and lactic acid in wastewater, Industrial Crops and Products, 10.1016/j.indcrop.2022.115503, 187, 115503, 2022.11.
8. Le Tran Thanh Liem, Yukihiro Tashiro, Pham Van Trong Tinh, Kenji Sakai. , Reduction in Greenhouse Gas Emission from Seedless Lime Cultivation Using Organic Fertilizer in a Province in Vietnam Mekong Delta Region, Sustainability, (doi.org/10.3390/su14106102), 14, 6102, 2022.05.
9. Natsumi Ishida, Yoshihisa Kawano, Ryo Fukui, Min Zhang, Yukihiro Tashiro, Kenji Sakaia, Clarification of the dynamic autothermal thermophilic aerobic digestion process using metagenomic analysis, Microbiology Spectrum, doi.org/10.1128/spectrum.00561-22, in press, 2022.04.
10. Kota Watanabe, Azusa Yamada, Yuri Nishi, Yukihiro Tashiro, Kenji Sakai, Host factors that shape the bacterial community structure on scalp hair shaft, Scientific Reports, doi.org/10.1038/s41598-021-96767-w, 11, 1, 17711, 2021.09, [URL].
11. Siyuan Yue, Takaharu Mizoguchi, Toshiya Kohara, Min Zhang, Kota Watanabe, Hirokuni Miyamoto, Yukihiro Tashiro, Kenji Sakai, Meta-fermentation system with a mixed culture for the production of optically pure L-lactic acid can be reconstructed using the minimum isolates with a simplified pH control strategy, Biotechnology Journal, doi.org/10.1002/biot.202100277, 16, 11, 2100277, 2021.11.
12. Min Zhang, Yukihiro Tashiro, Yuya Asakura, Natsumi Ishida, kota Watanabe, Siyuan Yue, Akiko Maruyama-Nakashita, Kenji Sakai, Lab-scale autothermal thermophilic aerobic digestion can maintain and remove nitrogen by controlling shear stress and oxygen supply system, Journal of Bioscience and Bioengineering, doi:10.1016/j.jbiosc.2021.05.008, 132, 3, 293-301, 2021.09.
13. Kota Watanabe, Azusa Yamada, Yuri Nishi, Yukihiro Tashiro, Kenji Sakai, Relationship between the bacterial community structures on human hair and scalp, Bioscience, Biotechnology, and Biochemistry, doi.org/10.1080/09168451.2020.1809989, 84, 12, 2585-2596, 2020.12, In this study, we investigated and compared characteristics of the bacterial community structures on hair (scalp hair) and scalp in 18 individuals. Significant differences were found between the sites, in terms of cell density, alpha and beta diversity, and relative abundance of the phyla, Firmicutes and Proteobacteria, whereas no difference was found in relative abundance of the phylum Actinobacteria. Bacteria of the genus Cutibacterium showed similar relative abundance at both sites, whereas those of genus Pseudomonas were highly abundant on hair, and those of genus Staphylococcus were significantly lesser in abundance on hair than on scalp. Statistical correlations between the sites were high for the individual relative abundance of five major operational taxonomic units (OTUs). This suggests that the bacterial community structure on hair is composed of hair-specific genus, Pseudomonas, and skin-derived genera, Cutibacterium and Staphylococcus, and is distinguishable from other human skin microbiomes..
14. Yuh Shiwa, Haruko Fujiwara, Mao Numaguchi, Mohamed Ali Abdel-Rahman, Keisuke Nabeta, Yu Kanesaki, Yukihiro Tashiro, Takeshi Zendo, Naoto Tanaka, Nobuyuki Fujita, Hirofumi Yoshikawa, Kenji Sonomoto, Mariko Shimizu-Kadota, , Transcriptome profile of carbon catabolite repression in an efficient L-(+)-lactic acid-producing bacterium Enterococcus mundtii QU25 grown in media with combinations of cellobiose, xylose, and glucose, PLoS ONE, doi.org/10.1371/journal.pone.0242070, 15, e0242070, 2020.11.
15. Rizki Fitria Darmayanti, Yukihiro Tashiro, Kenji Sakai, Kenji Sonomoto, Ari Susanti, Bekti Palupi, Meta Fitri Rizkiana, Biobutanol production using high cell density fermentation in a large extractant volume, International Journal of Renewable Energy Development, doi.org/10.14710/ijred.2020.29986, 9, 3, 431-437, 2020.10.
16. Mohamed Ali Abdel-Rahman, Jiaming Tan, Yukihiro Tashiro, Takeshi Zendo, Kenji Sakai, Kenji Sonomoto, Non-carbon loss long-term continuous lactic acid production from mixed sugars using thermophilic Enterococcus faecium QU 50, Biotechnology and Bioengineering, 10.1002/bit.27313, 117, 6, 1673-1683, 2020.06, In this study, a non-sterile (open) continuous fermentation (OCF) process with no-carbon loss was developed to improve lactic acid (LA) productivity and operational stability from the co-utilization of lignocellulose-derived sugars by thermophilic Enterococcus faecium QU 50. The effects of different sugar mixtures on LA production were firstly investigated in conventional OCF at 50°C, pH 6.5 and a dilution rate of 0.20 hr−1. The xylose consumption ratio was greatly lower than that of glucose in fermentations with glucose/xylose mixtures, indicating apparent carbon catabolite repression (CCR). However, CCR could be efficiently eliminated by feeding solutions containing the cellobiose/xylose mixture. In OCF at a dilution rate ca. 0.10 hr−1, strain QU 50 produced 42.6 g L−1 of l-LA with a yield of 0.912 g g−1-consumed sugars, LA yield of 0.655 g g−1 based on mixed sugar-loaded, and a productivity of 4.31 g L−1 hr−1 from simulated energy cane hydrolyzate. In OCF with high cell density by cell recycling, simultaneous and complete co-utilization of sugars was achieved with stable LA production at 60.1 ± 3.25 g L−1 with LA yield of 0.944 g g−1-consumed sugar and LA productivity of 6.49 ± 0.357 g L−1 hr−1. Besides this, a dramatic increase in LA yield of 0.927 g g−1 based on mixed sugar-loaded with prolonged operational stability for at least 500 hr (>20 days) was established. This robust system demonstrates an initial green step with a no-carbon loss under energy-saving toward the feasibility of sustainable LA production from lignocellulosic sugars..
17. Hui Zou, Ming Gao, Miao Yu, Wenyu Zhang, Shuang Zhang, Chuanfu Wu, Yukihiro Tashiro, Qunhui Wang, Methane production from food waste via mesophilic anaerobic digestion with ethanol pre-fermentation
Methanogenic pathway and microbial community analyses, Bioresource Technology, 10.1016/j.biortech.2019.122450, 297, 2020.02, To investigate the methanogenic pathway and microbial community in a mesophilic anaerobic digestion (AD) system with food waste (FW) ethanol pre-fermentation (EP), two semi-continuous AD systems were operated by feeding FW with (PSR) and without EP (control). In this study, δ13C-ethanol was supplemented as solo substrate for AD sludge when the reactors operation stabilized to analyze the methanogenic pathways. The results suggested that approximately 59.3% of methane was produced from acetotrophic methanogens, while 40.7% was formed by hydrogenotrophic methanogens in the PSR group. On the other hand, compared with control, methane produced via CO2 reduction pathway was increased by 4.70%. Meanwhile, the composition variations of the microbial community in AD supported the above conclusion, since the relative abundances of Clostridium and Methanobacterium were enhanced by 7.6% and 10.2%, respectively in PSR reactor. These results provided a theoretical basis for AD applications and biogas yield improvements with EP process..
18. ＠Kulwadee Khotchanalekha, Weerasak Saksirirat, Supat Isarangkool Na Ayutthaya, Kenji Sakai, Yukihiro Tashiro, Yuki Okugawa, Saowanit Tongpim, Isolation and selection of plant growth promoting endophytic bacteria associated with healthy hevea brasiliensis for use as plant growth promoters in rubber seedlings under salinity stress, Chiang Mai Journal of Science, 47, 1, 39-48, 2020.01, Endophytic bacteria are defined as microorganisms that live in plant tissues for the whole or part of their lives without causing adverse effect on the host plant. Bacterial endophytes have been reported as plant growth promoters in several kinds of plants under normal and stress conditions. The aims of this study were to isolate plant growth-promoting endophytic bacteria from healthy Para rubber trees (Hevea brasiliensis) and investigate their effects on the growth of Para rubber seedlings grown under salinity stress. Among the 415 endophytic isolates obtained, isolates AP6A3 and ER212 were chosen for in vivo study under greenhouse conditions. Isolate AP6A3 produced a phytohormone indole acetic acid (IAA) at 58.39 µg/ml and ACC deaminase; it was able to fix nitrogen, having a nitrogenase activity at 64.14 µmol C2H4/tube/h determined using acetylene reduction assay but could not solubilize inorganic phosphate. Isolate ER212 strongly solubilized tricalcium phosphate and released soluble phosphate at 197.01 µg/ml; it produced only trace amounts of IAA, was absent of ACC deaminase and did not fix nitrogen. Isolates AP6A3 and ER212 tolerated salinity well, at least 7% and 10% NaCl, respectively. Characterization of these two isolates by conventional methods displayed that isolates AP6A3 and ER212 belonged to the genus Enterobacter and Bacillus, respectively. These two endophytes were then employed in greenhouse experiments with Para rubber seedlings grown under salinity stress (500 mM NaCl). Interestingly, both endophytic isolates significantly enhanced the growth (based on shoot height, stem diameter, root length, fresh and dry weight) of Para rubber seedlings when compared to the un-inoculated seedlings. These results demonstrated that the endophytic Enterobacter sp. strain AP6A3 and Bacillus sp. strain ER212 had a potential application as bio-fertilizer for plants grown in saline environments..
19. Tao Zhao, Yukihiro Tashiro, Kenji Sonomoto, Smart fermentation engineering for butanol production
designed biomass and consolidated bioprocessing systems, Applied Microbiology and Biotechnology, 10.1007/s00253-019-10198-2, 103, 23-24, 9359-9371, 2019.12, There is a renewed interest in acetone-butanol-ethanol (ABE) fermentation from renewable substrates for the sustainable and environment-friendly production of biofuel and platform chemicals. However, the ABE fermentation is associated with several challenges due to the presence of heterogeneous components in the renewable substrates and the intrinsic characteristics of ABE fermentation process. Hence, there is a need to select optimal substrates and modify their characteristics suitable for the ABE fermentation process or microbial strain. This “designed biomass” can be used to establish the consolidated bioprocessing systems. As there are very few reports on designed biomass, the main objectives of this review are to summarize the main challenges associated with ABE fermentation from renewable substrates and to introduce feasible strategies for designing the substrates through pretreatment and hydrolysis technologies as well as through the establishment of consolidated bioprocessing systems. This review offers new insights on improving the efficiency of ABE fermentation from designed renewable substrates..
20. Takahiro Kihara, Takuya Noguchi, Yukihiro Tashiro, Kenji Sakai, Kenji Sonomoto, Highly efficient continuous acetone–butanol–ethanol production from mixed sugars without carbon catabolite repression, Bioresource Technology Reports, 10.1016/j.biteb.2019.03.017, 7, 2019.09, Factors including the composition and concentration of mixed sugars, dilution rate, and cell density were examined to establish a highly efficient continuous acetone–butanol–ethanol (ABE)fermentation process using Clostridium saccharoperbutylacetonicum N1-4. During conventional continuous fermentation at a dilution rate of 0.15 h−1, the glucose/xylose mixture exhibited carbon catabolite repression (CCR)with an intensity (I CCR)of 4.18 and ABE productivity of 0.574 g L−1 h−1, while CCR was alleviated using a cellobiose/xylose mixture with 1.60 and 1.09 g L−1 h−1, respectively. Continuous fermentation with high cell density by cell recycling improved ABE productivity to 5.32 g L−1 h−1 at a dilution rate of 0.686 h−1 owing to high xylose consumption. Further optimization of mixed sugar concentration in the feeding medium induced the best performance of continuous ABE production from mixed sugar without CCR, relative to previous studies: ABE productivity, 6.09 g L−1 h−1; ABE yield, 0.214 g g−1; I CCR, 1.48..
21. Tao Zhao, Kento Yasuda, Yukihiro Tashiro, Rizki Fitria Darmayanti, Kenji Sakai, Kenji Sonomoto, Semi-hydrolysate of paper pulp without pretreatment enables a consolidated fermentation system with in situ product recovery for the production of butanol, Bioresource Technology, 10.1016/j.biortech.2019.01.043, 278, 57-65, 2019.04, Utilization of lignocellulosic biomasses for biobutanol fermentation usually requires costly processes of pretreatment and enzymatic hydrolysis. In this study, paper pulp (93.2% glucan) was used as a starting biomass material to produce biobutanol. We conducted enzymatic semi-hydrolysis of paper pulp without pretreatment and with low enzyme loading, which produced high concentrations of cellobiose (13.9 g L
−1
) and glucose (21.3 g L
−1
). In addition, efficient fermentation of the semi-hydrolysate was achieved similar to that with the use of commercial sugars without inhibitors. Finally, we designed a novel non-isothermal simultaneous saccharification and fermentation with in situ butanol recovery, which was composed of a repeated semi-hydrolysis process and successive butanol-extractive fermentation process under the respective optimal conditions. The consolidated system improved butanol production, butanol yields, and butanol productivities and enabled repeated use of medium when compared with other integrated hydrolysis and fermentation processes..
22. Kota Watanabe, Eiji Nishi, Yukihiro Tashiro, Kenji Sakai, Mode and structure of the bacterial community on human scalp hair, Microbes and Environments, 10.1264/jsme2.ME19018, 34, 3, 252-259, 2019.01, Bacterial communities on various parts of the human body are distinct. We were the first to report the existence of a stable bacterial community on human scalp hair and demonstrated that an analysis of its structure by terminal restriction fragment length polymorphism (T-RFLP) is helpful for individual discrimination. However, the ecology of the bacterial community on human scalp hair has not yet been elucidated in detail. We herein investigated the mode, quantity, and phylogeny of bacterial communities on the human hair shaft and root and showed the results obtained from one representative individual. Direct SEM observations of hair, without a pretreatment, confirmed the ubiquitous presence of bacteria-like coccoids and rods on the shaft and root of hair from the human scalp, with 105-106 cells cm-2 of hair and 107 cells cm-2 of hair, respectively. These values corresponded to the 16S rRNA gene copy numbers obtained by qPCR. These numbers were not significantly affected by detergent washing. These results represented those obtained from many individuals with different hair lengths, ages, and gender. The major OTUs on the human scalp hair shaft and root were the same and included two species of Pseudomonas (phylum Proteobacteria), Cutibacterium and Lawsonella (phylum Actinobacteria), and Staphylococcus (phylum Firmicutes). These results suggest that major bacteria on the human hair shaft are indigenous and derived from the hair root..
23. Diana Mohd-Nor, Norhayati Ramli, Siti Suhailah Sharuddin, Mohd Ali Hassan, Nurul Asyifah Mustapha, Hidayah Ariffin, Kenji Sakai, Yukihiro Tashiro, Yoshihito Shirai, Toshinari Maeda, Dynamics of microbial populations responsible for biodegradation during the full-scale treatment of palm oil mill effluent, Microbes and Environments, 10.1264/jsme2.ME18104, 34, 2, 121-128, 2019.01, Despite efforts to address the composition of the microbial community during the anaerobic treatment of palm oil mill effluent (POME), its composition in relation to biodegradation in the full-scale treatment system has not yet been extensively examined. Therefore, a thorough analysis of bacterial and archaeal communities was performed in the present study using MiSeq sequencing at the different stages of the POME treatment, which comprised anaerobic as well as facultative anaerobic and aerobic processes, including the mixed raw effluent (MRE), mixing pond, holding tank, and final discharge phases. Based on the results obtained, the following biodegradation processes were suggested to occur at the different treatment stages: (1) Lactobacillaceae (35.9%) dominated the first stage, which contributed to high lactic acid production; (2) the higher population of Clostridiaceae in the mixing pond (47.7%) and Prevotellaceae in the holding tank (49.7%) promoted acetic acid production; (3) the aceticlastic methanogen Methanosaetaceae (0.6–0.8%) played a role in acetic acid degradation in the open digester and closed reactor for methane generation; (4) Syntrophomonas (21.5–29.2%) appeared to be involved in the degradation of fatty acids and acetic acid by syntrophic cooperation with the hydrogenotrophic methanogen, Methanobacteriaceae (0.6–1.3%); and (5) the phenols and alcohols detected in the early phases, but not in the final discharge phase, indicated the successful degradation of lignocellulosic materials. The present results contribute to a better understanding of the biodegradation mechanisms involved in the different stages of the full-scale treatment of POME..
24. Rizki Fitria Darmayanti, Yukihiro Tashiro, Takuya Noguchi, Ming Gao, Kenji Sakai, Kenji Sonomoto, Novel biobutanol fermentation at a large extractant volume ratio using immobilized Clostridium saccharoperbutylacetonicum N1-4, Journal of Bioscience and Bioengineering, 10.1016/j.jbiosc.2018.06.006, 126, 6, 750-757, 2018.12, Product inhibition by butanol and acetone is a known drawback in acetone-butanol-ethanol (ABE) fermentation. Extractive fermentation improves butanol production by several ABE-producing Clostridium spp., but only low volume ratios (e/Vb) have been studied. Here, a novel extractive fermentation process was developed using Clostridium saccharoperbutylacetonicum N1-4 and a large Ve/Vb ratio. A mixture of oleyl alcohol-tributyrin (1:1 (v/v)) yielded high distribution coefficients for both butanol (3.14) and acetone (0.660). Although a fed-batch culture using free cells and the oleyl alcohol-tributyrin mixture at a Ve/Vb ratio of 5 had a lag phase of >24 h, it produced a higher concentration of total butanol (i.e., butanol produced in all the phases per broth volume used) of 24.2 g/L-broth after 96 h compared with 14.4 g/L-broth at a Ve/Vb ratio of 1, resulting in a low butanol concentration in the aqueous phase. The use of cells immobilized with calcium alginate beads shortened the lag phase to e/Vb ratio of 5, resulting butanol concentrations of 30.9 g/L-broth and 27.7 g/L-broth, respectively. The 3-phases fed-batch extractive fermentation at a Ve/Vb ratio of 10 showed a better performance compared with published reports: a total butanol concentration of 64.6 g/L-broth and a butanol yield to consumed sugar of 0.378 C-mol/C-mol..
25. Tao Zhao, Yukihiro Tashiro, Jin Zheng, Kenji Sakai, Kenji Sonomoto, Semi-hydrolysis with low enzyme loading leads to highly effective butanol fermentation, Bioresource Technology, 10.1016/j.biortech.2018.05.056, 264, 335-342, 2018.09, To improve butanol fermentation efficiencies, semi-hydrolysate with low enzyme loading using H2SO4 pretreated rice straw was designed, which preferably produced cellobiose with xylose (instead of glucose). Fermentation of semi-hydrolysates avoided carbon catabolite repression (CCR) and produced higher butanol yield to enzyme loading (0.0290 g U−1), a newly proposed parameter, than the conventional glucose-oriented hydrolysate (0.00197 g U−1). Further, overall butanol productivity was improved from 0.0628 g L−1 h−1 to 0.265 g L−1 h−1 during fermentation of undetoxified semi-hydrolysate by using high cell density. A novel simultaneously repeated hydrolysis and fermentation (SRHF) was constructed by recycling of enzymes and cells, which further improved butanol yield to enzyme loading by 183% and overall butanol productivity by 6.04%. Thus, semi-hydrolysate with SRHF is a smartly designed biomass for efficient butanol fermentation of lignocellulosic materials..
26. Huijun Cheng, Yuya Asakura, Kosuke Kanda, Ryo Fukui, Yoshihisa Kawano, Yuki Okugawa, Yukihiro Tashiro, Kenji Sakai, Dynamic bacterial community changes in the autothermal thermophilic aerobic digestion process with cell lysis activities, shaking and temperature increase, Journal of Bioscience and Bioengineering, 10.1016/j.jbiosc.2018.02.012, 126, 2, 196-204, 2018.08, Autothermal thermophilic aerobic digestion (ATAD) is conducted for stabilization of sludge waste and is driven by the action of various microorganisms under aerobic conditions. However, the mechanism controlling bacterial community changes during ATAD via three (initial, middle and final) phases is currently unclear. To investigate this mechanism, activity analysis and a microcosm assay with shaking were performed on a bacterial community during the initial, middle, and final phases of incubation. Cell lysis activities toward gram-negative bacteria, but not gram-positive bacteria, were detected in the ATAD samples in the middle and final phases. During shaking incubation in initial-phase samples at 30 °C, major operational taxonomic units (OTUs) related to Acinetobacter indicus and Arcobacter cibarius dramatically increased along with decreases in several major OTUs. In middle-phase samples at 45 °C, we observed a major alteration of OTUs related to Caldicellulosiruptor bescii and Aciditerrimonas ferrireducens, together with distinct decreases in several other OTUs. Final-phase samples maintained a stable bacterial community with major OTUs showing limited similarities to Heliorestis baculata, Caldicellulosiruptor bescii, and Ornatilinea apprima. In conclusion, the changes in the bacterial community observed during ATAD could be partially attributed to the cell lysis activity toward gram-negative bacteria in the middle and final phases. The microcosm assay suggested that certain physical factors, such as a high oxygen supply and shearing forces, also might contribute to bacterial community changes in the initial and middle phases, and to the stable bacterial community in the final phase of ATAD..
27. Winai Jamjan, Chanwit Suriyachadkun, Somboon Tanasupawat, Kenji Sakai, Yukihiro Tashiro, Yuki Okugawa, Saowanit Tongpim, Amycolatopsis silviterrae sp. Nov., isolated from forest soil, International Journal of Systematic and Evolutionary Microbiology, 10.1099/ijsem.0.002687, 68, 5, 1455-1460, 2018.05, A novel actinobacterial strain, designated C12CA1T, was isolated from forest soil in the conservation area of Chulabhorn dam, Thailand, and its taxonomic position was determined by using a polyphasic approach. Strain C12CA1T contained meso-2,6 diaminopimelic acid in the cell-wall peptidoglycan, and arabinose and galactose as diagnostic sugars of the whole-cell hydrolysate. On the basis of morphological and chemotaxonomic characteristics, strain C12CA1T was classified in the genus Amycolatopsis. It contained MK-9(H4) as the predominant menaquinone, C16:0, iso-C15:0 and iso-C16:0 as the major cellular fatty acids, and several phospholipids consisting of diphosphotidylglycerol, phosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol, hydroxyphosphatidylethanolamine, phosphatidylinositol mannosides and an unidentified glucosamine-containing phospholipid. Based on 16S rRNA gene sequence and phylogenetic analyses, strain C12CA1T was closely related to Amycolatopsis vancoresmycina DSM 44592T (98.96%) and Amycolatopsis pretoriensis JCM 12673T (98.82%). The strain exhibited low DNA-DNA relatedness values with A. vancoresmycina DSM 44592T (6.9±0.2-11.6±1.9%) and A. pretoriensis JCM 12673T (8.8±0.3-9.2±1.8%). The DNA G+C content of strain C12CA1T was 69.8 mol%. Based on the results of polyphasic characterization, strain C12CA1T represents a novel species of the genus Amycolatopsis, for which the name Amycolatopsis silviterrae sp. nov. is proposed. The type strain is C12CA1T (=TBRC 1456T=NBRC 111116T)..
28. Yukihiro Tashiro, Kosuke Kanda, Yuya Asakura, Toshihiko Kii, Huijun Cheng, Pramod Poudel, Yuki Okugawa, Kosuke Tashiro, Kenji Sakai, A unique autothermal thermophilic aerobic digestion process showing a dynamic transition of physicochemical and bacterial characteristics from the mesophilic to the thermophilic phase, Applied and Environmental Microbiology, 10.1128/AEM.02537-17, 84, 6, 2018.03, A unique autothermal thermophilic aerobic digestion (ATAD) process has been used to convert human excreta to liquid fertilizer in Japan. This study investigated the changes in physicochemical and bacterial community characteristics during the full-scale ATAD process operated for approximately 3 weeks in 2 different years. After initiating simultaneous aeration and mixing using an air-inducing circulator (aerator), the temperature autothermally increased rapidly in the first 1 to 2 days with exhaustive oxygen consumption, leading to a drastic decrease and gradual increase in oxidation-reduction potential in the first 2 days, reached > 50°C in the middle 4 to 6 days, and remained steady in the final phase. Volatile fatty acids were rapidly consumed and diminished in the first 2 days, whereas the ammonia nitrogen concentration was relatively stable during the process, despite a gradual pH increase to 9.3. Principal-coordinate analysis of 16S rRNA gene amplicons using next-generation sequencing divided the bacterial community structures into distinct clusters corresponding to three phases, and they were similar in the final phase in both years despite different transitions in the middle phase. The predominant phyla (closest species, dominancy) in the initial, middle, and final phases were Proteobacteria (Arcobacter trophiarum, 19 to 43%; Acinetobacter towneri, 6.3 to 30%), Bacteroidetes (Moheibacter sediminis, 43 to 54%), and Firmicutes (Thermaerobacter composti, 11 to 28%; Heliorestis baculata, 2.1 to 16%), respectively. Two predominant operational taxonomic units (OTUs) in the final phase showed very low similarities to the closest species, indicating that the process is unique compared with previously published ones. This unique process with three distinctive phases would be caused by the aerator with complete aeration..
29. Hoe Seng Tin, Kishneth Palaniveloo, Junia Anilik, Mathavan Vickneswaran, Yukihiro Tashiro, Charles S. Vairappan, Kenji Sakai, Impact of Land-use Change on Vertical Soil Bacterial Communities in Sabah, Microbial Ecology, 10.1007/s00248-017-1043-6, 75, 2, 459-467, 2018.02, Decline in forest productivity due to forest conversion is defining the Bornean landscape. Responses of bacterial communities due to land-use changes are vital and could define our understanding of ecosystem functions. This study reports the changes in bacterial community structure in organic soil (0–5 cm; O-Horizon) and organic-mineral soil (5–15 cm; A-Horizon) across Maliau Basin Conservation Area old growth forest (MBOG), Fragment E logged forest (FELF) located in Kalabakan Forest Reserve to Benta Wawasan oil palm plantation (BWOP) using two-step PCR amplicon analysis of bacteria DNA on Illumina Miseq next generation sequencing. A total of 30 soil samples yielded 893,752-OTU reads at ≥97% similarity from 5,446,512 good quality sequences. Soil from BWOP plantation showed highest unshared OTUs for organic (49.2%) and organic-mineral (50.9%) soil. MBOG soil showed a drop in unshared OTUs between organic (48.6%) and organic-mineral (33.9%). At phylum level, Proteobacteria dominated MBOG but shifted to Actinobacteria in logged and plantation soil. Present findings also indicated that only FELF exhibited change in bacterial communities along the soil depth, moving from the organic to the organic-mineral layer. Both layers of BWOP plantation soils deviated from other forests’ soil in β-diversity analysis. To our knowledge, this is the first report on transitions of bacterial community structures with different soil horizons in the tropical rainforest including Borneo, Sabah. Borneo tropical soils form a large reservoir for soil bacteria and future exploration is needed for fully understanding the diversity structure and their bacterial functional properties..
30. Siti Suhailah Sharuddin, Norhayati Ramli, Diana Mohd-Nor, Mohd Ali Hassan, Toshinari Maeda, Yoshihito Shirai, Kenji Sakai, Yukihiro Tashiro, Shift of low to high nucleic acid bacteria as a potential bioindicator for the screening of anthropogenic effects in a receiving river due to palm oil mill effluent final discharge, Ecological Indicators, 10.1016/j.ecolind.2017.10.020, 85, 79-84, 2018.02, The microbiological effects of palm oil mill effluent (POME) final discharge upon a receiving river were assessed in this study by using the nucleic acid double staining assay based on flow cytometry. The functional status of the bacterial community at the single-cell level was determined with regards to their abundance, viability and nucleic acid content to monitor the effects of POME final discharge on the affected river. The effluent resulted in the increment of the total cell concentration (TCC) and viable cells which were correlated with the increment of biological oxygen demand (BOD5) and total organic carbon (TOC) concentrations in the receiving river. The shift of low nucleic acid (LNA) to high nucleic acid (HNA) bacterial cells in the affected river suggested the transformation of dormant to active cells due to the POME final discharge. This is the first study to report on the shift of LNA/HNA ratios which may serves as a potential bioindicator in the screening of the anthropogenic effects due to POME final discharge in river water with originally high LNA proportions. Monitoring the effluent discharge at low trophic level using flow cytometry is a rapid and sensitive approach when compared to the current physicochemical assessment method. This approach allows for the screening of river water contamination caused by POME final discharge prior to a full assessment using the recently proposed specific bacterial indicators..
31. Hirokuni Miyamoto, Hisashi Miyamoto, Yukihiro Tashiro, Kenji Sakai, Hiroaki Kodama, Studies on highly functional fermented-products made from unutilized biomass resources by thermophilic bacteria, Seibutsu-kogaku Kaishi, 96, 2, 56-63, 2018.01.
32. Waill A. Elkhateeb, Amira M. Hamdan, Takeshi Zendo, Yukihiro Tashiro, Kenji Sonomoto, Innovative green chemical production by novel egyptian aquatic bacterial isolates, Journal of the Faculty of Agriculture, Kyushu University, 63, 2, 331-337, 2018.01, Over the last decade, lactic acid has attracted great attention as a natural preservative in food and cosmetics. Poly-lactic acid can be used in bioplastic production that can serve as a biobased alternative to oil-derived plastics such as polyethylene and polystyrene. In this study, a total of 16 novel marine lactic acid bacteria isolates were selected from samples collected along the Alexandrian Mediterranean Sea coast of Egypt. Both biochemical characteristics of LAB isolates supported by 16S rRNA gene sequence analysis and NCBI online database tool showed that the obtained isolates belonged to the genera Pediococcus and Lactobacillus. The results of lactic acid fermentation using those marine isolates revealed improved homo-lactic acid fermentation (100% optically pure lactic acid produced) from low xylose concentration after 24 h at initial pH 5.0 and 50°C. To the best of our knowledge, this is the first report on marine bacteria as candidates for the production of green chemicals in the Mediterranean Sea in Egypt..
33. Jin Zheng, Yukihiro Tashiro, Tao Zhao, Qunhui Wang, Kenji Sakai, Kenji Sonomoto, Enhancement of acetone-butanol-ethanol fermentation from eucalyptus hydrolysate with optimized nutrient supplementation through statistical experimental designs, Renewable Energy, 10.1016/j.renene.2017.05.097, 113, 580-586, 2017.12, Eucalyptus has been previously suggested as a potential substrate for acetone-butanol-ethanol (ABE) production without nutrient supplementation; however, incomplete sugar consumption has prevented improvement of ABE production. Cellulase loading with 35 FPU g−1 was first optimized in terms of high hydrolysis efficiency (95%). However, only 0.43 g L−1 ABE production and 3.44% glucose consumption rate were achieved. To improve ABE production from eucalyptus hydrolysate, supplementation of 6 nutrients in common tryptone-yeast extract (TY) medium were investigated by statistical approaches. Three nutrients including yeast extract, tryptone, and FeSO4·7H2O were screened as significant nutrients for ABE production. Subsequently, use of a modified TY medium (MTY medium: yeast extract 3.04 g L−1, tryptone 7.64 g L−1, FeSO4·7H2O 15.3 mg L−1), which was subsequently predicted by Plackett-Burman and Box-Behnken designs to stimulate ABE production, resulted in ca. 40-fold increase in ABE concentration (16.9 g L−1) and a glucose consumption rate of 100%. We first examined previously uninvestigated nutrition combinations using Plackett-Burman and Box-Behnken designs for high ABE production from eucalyptus hydrolysate. This study shows that statistical method would be a powerful tool for the optimization and enhancement of ABE production from eucalyptus hydrolysate..
34. Siti Suhailah Sharuddin, Norhayati Ramli, Mohd Ali Hassan, Nurul Asyifah Mustapha, Afzufira Amran, Diana Mohd-Nor, Kenji Sakai, Yukihiro Tashiro, Yoshihito Shirai, Toshinari Maeda, Bacterial community shift revealed Chromatiaceae and Alcaligenaceae as potential bioindicators in the receiving river due to palm oil mill effluent final discharge, Ecological Indicators, 10.1016/j.ecolind.2017.07.038, 82, 526-529, 2017.11, A thorough outlook on the effect of palm oil mill effluent (POME) final discharge towards bacterial community dynamics in the receiving river is provided in this study by using a high-throughput MiSeq. The shift of bacterial composition could be used to determine the potential bacterial indicators to indicate contamination caused by POME. This study showed that the POME final discharge did not only alter the natural physicochemical properties of the river water but also caused the reduction of bacterial diversity in the receiving river. The Chromatiaceae and Alcaligenaceae which were not detected in the upstream but were detected in the downstream part of the river are proposed as the indicator bacteria to indicate the river water contamination caused by POME final discharge. The emergence of either one or both bacteria in the downstream part of the river were shown to be carried over by the effluent. Therefore, an accurate pollution monitoring approach using bacterial indicator is expected to complement the conventional POME pollution assessment method which is currently dependent on the physicochemical properties of the final discharge. This is the first study that reported on the potential indicator bacteria for the assessment of river water contamination caused by POME final discharge..
35. Kathrina Mae Bienes, Minoru Ito, Kota Shiotsuka, Sachi Yamaguchi, Taiki Fujioka, Yukihiro Tashiro, Kenji Sakai, Ecological distribution of extremely thermophilic bacteria belonging to the genus Calditerricola using the novel enrichment MPN-PCR method, Journal of Bioscience and Bioengineering, 10.1016/j.jbiosc.2017.06.003, 2017.11, A unique compost called Satsuma soil is produced from sewage sludge by a hyperthermal composting process in Kagoshima City, Japan. The composting process is carried out at a controlled temperature of at least 80°C and the resulting compost might be useful for recycling sustainable agricultural products. The extremely thermophilic bacterial genus Calditerricola was initially isolated from the high-temperature compost. Likewise, the bacteria were previously isolated from material sludge. It is believed that bacteria in this genus might be involved in the hyperthermal composting process. Calditerricola bacteria are distributed not only in compost, but also in all of its material sludge, and are more abundant in material sludge than in compost. Moreover, based on investigations of samples near geothermal areas in high temperature conditions, such as volcanoes, Calditerricola was presumed to originate in the volcanic ash of Mt. Sakurajima in Kagoshima City, Japan. However, its precise origin and ecology are unclear. Thus, in this study, a new molecular biological method called enrichment most probable number (MPN)-PCR (eMPN-PCR) was established and used to quantitatively investigate the population and distribution of the extreme thermophile Calditerricola in environmental samples using genus-specific PCR primers. The eMPN-PCR method was an effective quantitative detection method with high sensitivity, yielding MPN estimates that were highly correlated with colony forming unit (CFU) estimates but a low detection threshold value..
36. Clament Fui Seung Chin, Yoshihide Furuya, Mohd Huzairi Mohd Zainudin, Norhayati Ramli, Mohd Ali Hassan, Yukihiro Tashiro, Kenji Sakai, Novel multifunctional plant growth–promoting bacteria in co-compost of palm oil industry waste, Journal of Bioscience and Bioengineering, 10.1016/j.jbiosc.2017.05.016, 124, 5, 506-513, 2017.11, Previously, a unique co-compost produced by composting empty fruit bunch with anaerobic sludge from palm oil mill effluent, which contributed to establishing a zero-emission industry in Malaysia. Little was known about the bacterial functions during the composting process and fertilization capacity of this co-compost. We isolated 100 strains from the co-compost on 7 types of enumeration media and screened 25 strains using in vitro tests for 12 traits, grouping them according to three functions: plant growth promoting (fixation of nitrogen; solubilization of phosphorus, potassium, and silicate; production of 3-indoleacetic acid, ammonia, and siderophore), biocontrolling (production of chitinase and anti-Ganoderma activity), and composting (degradation of lignin, xylan, and cellulose). Using 16S rRNA gene sequence analysis, 25 strains with strong or multi-functional traits were found belong to the genera Bacillus, Paenibacillus, Citrobacter, Enterobacter, and Kosakonia. Furthermore, several strains of Citrobacter sedlakii exhibited a plant growth-stimulation in vivo komatsuna plant cultivation test. In addition, we isolated several multifunctional strains; Bacillus tequilensis CE4 (biocontrolling and composting), Enterobacter cloacae subsp. dissolvens B3 (plant growth promoting and biocontrolling), and C. sedlakii CESi7 (plant growth promoting and composting). Some bacteria in the co-compost play significant roles during the composting process and plant cultivation after fertilization, and some multifunctional strains have potential for use in accelerating the biodegradation of lignocellulosic biomass, protecting against Ganoderma boninense infection, and increasing the yield of palm oil..
37. Ratchanu Meidong, Sompong Doolgindachbaporn, Winai Jamjan, Kenji Sakai, Yukihiro Tashiro, Yuki Okugawa, Saowanit Tongpim, A novel probiotic Bacillus siamensis B44v isolated from Thai pickled vegetables (Phak-dong) for potential use as a feed supplement in aquaculture, Journal of General and Applied Microbiology, 10.2323/jgam.2016.12.002, 63, 4, 246-253, 2017.09, The use of probiotic bacteria to control bacterial infection in farmed fish is of clear practical interest. The aims of this study were to isolate and select a probiotic Bacillus sp. and to evaluate the effects of its supplementation on the growth and disease resistance of hybrid catfish. Bacillus siamensis strain B44v, selectively isolated from Thai pickled vegetables (Phak-dong), displayed a high potential as a probiotic in catfish culture. This bacterium produced a bacteriocin-like substance and exhibited a broad-spectrum antibacterial activity inhibiting both Gram-positive and Gram-negative bacteria, especially the fish pathogens Aeromonas hydrophila and Streptococcus agalactiae. The susceptibility to all 14 antibiotics tested implies its less possibility to be the antibiotic-resistant bacterium. Bacillus siamensis strain B44v possessed interesting adhesion properties, as shown by its high percentages of hydrophobicity (64.8%), auto-agglutination (73.8%), co-aggregation (67.2% with A. hydrophila FW52 and 63.5% with S. agalactiae F3S), and mucin binding (88.7%). The strain B44v survived simulated gastrointestinal conditions and produced protease and cellulase enzymes. Hybrid catfish (C. macrocephalus × C. gariepinus) were employed in the feed-trial experiments. Fish fed diet containing strain B44v (107 CFU/g feed) displayed not only no mortality but also growth improvement. At the end of the feed trial, fish were challenged by an intraperitoneal injection of Aeromonas hydrophila FW52. The Bacillus siamensis strain B44v fed fish survived (75.0%; p
38. Mohd Huzairi Mohd Zainudin, Norhayati Ramli, Mohd Ali Hassan, Yoshihito Shirai, Kosuke Tashiro, Kenji Sakai, Yukihiro Tashiro, Bacterial community shift for monitoring the co-composting of oil palm empty fruit bunch and palm oil mill effluent anaerobic sludge, Journal of Industrial Microbiology and Biotechnology, 10.1007/s10295-017-1916-1, 44, 6, 869-877, 2017.06, A recently developed rapid co-composting of oil palm empty fruit bunch (OPEFB) and palm oil mill effluent (POME) anaerobic sludge is beginning to attract attention from the palm oil industry in managing the disposal of these wastes. However, a deeper understanding of microbial diversity is required for the sustainable practice of the co-compositing process. In this study, an in-depth assessment of bacterial community succession at different stages of the pilot scale co-composting of OPEFB-POME anaerobic sludge was performed using 454-pyrosequencing, which was then correlated with the changes of physicochemical properties including temperature, oxygen level and moisture content. Approximately 58,122 of 16S rRNA gene amplicons with more than 500 operational taxonomy units (OTUs) were obtained. Alpha diversity and principal component analysis (PCoA) indicated that bacterial diversity and distributions were most influenced by the physicochemical properties of the co-composting stages, which showed remarkable shifts of dominant species throughout the process. Species related to Devosia yakushimensis and Desemzia incerta are shown to emerge as dominant bacteria in the thermophilic stage, while Planococcus rifietoensis correlated best with the later stage of co-composting. This study proved the bacterial community shifts in the co-composting stages corresponded with the changes of the physicochemical properties, and may, therefore, be useful in monitoring the progress of co-composting and compost maturity..
39. Jiaming Tan, Mohamed Ali Sayed Mohamed Abdelrahman, Mao Numaguchi, Yukihiro Tashiro, Takeshi Zendo, Kenji Sakai, Kenji Sonomoto, Thermophilic Enterococcus faecium QU 50 enabled open repeated batch fermentation for l-lactic acid production from mixed sugars without carbon catabolite repression, RSC Advances, 10.1039/c7ra03176a, 7, 39, 24233-24241, 2017.05, Enterococcus faecium QU 50, a novel thermophilic l-lactic acid (LA) producing strain, was used in this study to ferment sugar mixtures into LA. Under the optimal fermentation conditions (50 °C, pH 6.5), strain QU 50 could ferment both mixed glucose/xylose sugars with relaxed CCR and mixed cellobiose/xylose sugars simultaneously without CCR to produce homo l-LA. The activity of enzymes related to xylose metabolism was also investigated. In the cells grown in a medium containing cellobiose/xylose, the activity of xylose isomerase and xylulose kinase, was 3.22 and 1.91 times higher, respectively, as compared to that of cells grown in a glucose/xylose medium. Strain QU 50 produced 70.8 g L-1 of l-LA with a yield of 1.04 g g-1 and a productivity of 2.95 g L-1 h-1 from simulated energy cane hydrolysate in batch fermentation. Immobilisation of strain QU 50 improved the operational stability of open repeated fermentation (three cycles), resulting in 61.1-64.3 g L-1 of l-LA with a yield of 1.01-1.02 g g-1 and a productivity of 3.22-3.82 g L-1 h-1. Thus, an efficient and cost-effective fermentation system was successfully established for l-LA production from sugar mixtures..
40. Eiji Nishi, Kota Watanabe, Yukihiro Tashiro, Kenji Sakai, Terminal restriction fragment length polymorphism profiling of bacterial flora derived from single human hair shafts can discriminate individuals, Legal Medicine, 10.1016/j.legalmed.2017.01.002, 25, 75-82, 2017.03, Human hairs are the trace evidence most commonly encountered at many crime scenes. However, they have not been effectively utilized for actual criminal investigations because of the low accuracy of their morphological inspection, low detection rate of short tandem repeat (STR) typing, and the problem of heteroplasmy in mitochondrial DNA analysis. Here, we examined the possibility of individual discrimination by comparing profiles of bacterial flora on hair. We carried out the profiling of terminal restriction fragment length polymorphisms (T-RFLP) of the amplified bacterial 16S ribosomal RNA (rRNA) gene from hair samples. Compared with existing STR typing methods that use hair roots, this method using hair shafts allowed the detection of stable bacterial DNA. We successfully obtained the T-RFLP profile from single hair shafts of all volunteers tested. The profiles were specific to each individual, and multiple profiles obtained from the individual him/herself showed higher similarity than those from different individuals. These individual-specific profiles were stably obtained from samples from most volunteers, when collected again after 6 months. Storage of the collected hair samples at −30 °C was effective for obtaining reproducible T-RF profiles. When unidentified hair samples collected in the laboratory were compared with a pre-constructed database, 17 of 22 hairs were assigned to a small group of people, including the corresponding individuals. These results show that T-RFLP analysis of bacterial flora on a hair shaft found at a crime scene could provide useful information for narrowing down a suspect..
41. Jin Zheng, Ming Gao, Qunhui Wang, Juan Wang, Xiaohong Sun, Qiang Chang, Yukihiro Tashiro, Enhancement of L-lactic acid production via synergism in open co-fermentation of Sophora flavescens residues and food waste, Bioresource Technology, 10.1016/j.biortech.2016.11.055, 225, 159-164, 2017.02, In this study, Sophora flavescens residues (SFR) were used for L-lactic acid production and were mixed with food waste (FW) to assess the effects of different compositions of SFR and FW. Positive synergistic effects of mixed substrates were achieved with co-fermentation. Co-fermentation increased the proportion of L-lactic acid by decreasing the co-products of ethanol and other organic acids. A maximum L-lactic acid concentration of 48.4 g/L and L-lactic acid conversion rate of 0.904 g/g total sugar were obtained through co-fermentation of SFR and FW at the optimal ratio of 1:1.5. These results were approximately 6-fold those obtained during mono-fermentation of SFR. Co-fermentation of SFR and FW provides a suitable C/N ratio and pH for effective open fermentative production of L-lactic acid..
42. Pramod Poudel, Yukihiro Tashiro, Hirokuni Miyamoto, Hisashi Miyamoto, Yuki Okugawa, Kenji Sakai, Development of a systematic feedback isolation approach for targeted strains from mixed culture systems, Journal of Bioscience and Bioengineering, 10.1016/j.jbiosc.2016.07.019, 123, 1, 63-70, 2017.01, Elucidation of functions of bacteria in a mixed culture system (MCS) such as composting, activated sludge system is difficult, since the system is complicating with many unisolated bacteria. Here, we developed a systematic feedback isolation strategy for the isolation and rapid screening of multiple targeted strains from MCS. Six major strains (Corynebacterium sphenisci, Bacillus thermocloacae, Bacillus thermoamylovorans, Bacillus smithii, Bacillus humi, and Bacillus coagulans), which are detected by denaturing gradient gel electrophoresis (DGGE) analysis in our previous study on MCS for L-lactic acid production, were targeted for isolation. Based on information of suitable cultivation conditions (e.g., media, pH, temperature) from the literature, feedback isolation was performed to form 136 colonies. The following direct colony matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) was optimised as the second screening to narrow down 20 candidate colonies from similar spectra patterns with six closest type strains. This step could distinguish bacteria at the species level with distance similarity scores ≥0.55 corresponding to 16S rRNA gene sequence similarity ≥98.2%, suggesting that this is an effective technique to minimize isolates close to targeted type strains. Analysis of 16S rRNA gene sequences indicated that two targeted strains and one strain related to the target had successfully been isolated, showing high similarities (99.5–100%) with the sequences from the DGGE bands, and that the other candidates were affiliated with three strains that were closely related to the target species. This study proposes a new method for systematic feedback isolation that may be useful for isolating targeted strains from MCS for further investigation..
43. Yukihiro Tashiro, Hanae Tabata, Asuka Itahara, Natsuki Shimizu, Kosuke Tashiro, Kenji Sakai, Unique hyper-thermal composting process in Kagoshima City forms distinct bacterial community structures, Journal of Bioscience and Bioengineering, 10.1016/j.jbiosc.2016.04.006, 122, 5, 606-612, 2016.11, A unique compost, Satsuma soil, is produced from three types of wastewater sludge using hyper-thermal processes at temperatures much higher than that of general thermophilic processes in Kagoshima City, Japan. We analyzed the bacterial community structures of this hyper-thermal compost sample and other sludges and composts by a high-throughput barcoded pyrosequencing method targeting the 16S rRNA gene. In total, 621,076 reads were derived from 17 samples and filtered. Artificial sequences were deleted and the reads were clustered based on the operational taxonomic units (OTUs) at 97% similarity. Phylum-level analysis of the hyper-thermal compost revealed drastic changes of the sludge structures (each relative abundance) from Firmicutes (average 47.8%), Proteobacteria (average 22.3%), and Bacteroidetes (average 10.1%) to two main phyla including Firmicutes (73.6%) and Actinobacteria (25.0%) with less Proteobacteria (∼0.3%) and Bacteroidetes (∼0.1%). Furthermore, we determined the predominant species (each relative abundance) of the hyper-thermal compost including Firmicutes related to Staphylococcus cohnii (13.8%), Jeotgalicoccus coquinae (8.01%), and Staphylococcus lentus (5.96%), and Actinobacteria related to Corynebacterium stationis (6.41%), and found that these species were not predominant in wastewater sludge. In contrast, we did not observe any common structures among eight other composts produced, using the hyper-thermal composts as the inoculums, under thermophilic conditions from different materials. Principle coordinate analysis of the hyper-thermal compost indicated a large difference in bacterial community structures from material sludge and other composts. These results suggested that a distinct bacterial community structure was formed by hyper-thermal composting..
44. Yukihiro Tashiro, Shota Inokuchi, Pramod Poudel, Yuki Okugawa, Hirokuni Miyamoto, Hisashi Miayamoto, Kenji Sakai, Novel pH control strategy for efficient production of optically active l-lactic acid from kitchen refuse using a mixed culture system, Bioresource Technology, 10.1016/j.biortech.2016.05.031, 216, 52-59, 2016.09, Uninvestigated control factors of meta-fermentation, the fermentative production of pure chemicals and fuels in a mixed culture system, were examined for production of optically pure l-lactic acid (LA) from food waste. In meta-fermentations by pH swing control, l-LA production with 100% optical purity (OPl-LA) was achieved even using unsterilized model kitchen refuse medium with preferential proliferation of l-LA-producing Bacillus coagulans, a minor member in the seed, whereas agitation decreased OPl-LA drastically. pH constant control shortened the fermentation time but decreased OPl-LA and LA selectivity (SLA) by stimulating growth of heterofermentative Bacillus thermoamylovorans. Deliberately switching from pH swing control to constant control exhibited the best performance for l-LA production: maximum accumulation, 39.2 g L-1; OPl-LA, 100%; SLA, 96.6%; productivity, 1.09 g L-1 h-1. These results present a novel pH control strategy for efficient l-LA production in meta-fermentation based on a concept different from that of pure culture systems..
45. Ming Gao, Yukihiro Tashiro, Qunhui Wang, Kenji Sakai, Kenji Sonomoto, High acetone-butanol-ethanol production in pH-stat co-feeding of acetate and glucose, Journal of Bioscience and Bioengineering, 10.1016/j.jbiosc.2016.01.013, 122, 2, 176-182, 2016.08, We previously reported the metabolic analysis of butanol and acetone production from exogenous acetate by 13C tracer experiments (Gao et al., RSC Adv., 5, 8486-8495, 2015). To clarify the influence of acetate on acetone-butanol-ethanol (ABE) production, we first performed an enzyme assay in Clostridium saccharoperbutylacetonicum N1-4. Acetate addition was found to drastically increase the activities of key enzymes involved in the acetate uptake (phosphate acetyltransferase and CoA transferase), acetone formation (acetoacetate decarboxylase), and butanol formation (butanol dehydrogenase) pathways. Subsequently, supplementation of acetate during acidogenesis and early solventogenesis resulted in a significant increase in ABE production. To establish an efficient ABE production system using acetate as a co-substrate, several shot strategies were investigated in batch culture. Batch cultures with two substrate shots without pH control produced 14.20 g/L butanol and 23.27 g/L ABE with a maximum specific butanol production rate of 0.26 g/(g h). Furthermore, pH-controlled (at pH 5.5) batch cultures with two substrate shots resulted in not only improved acetate consumption but also a further increase in ABE production. Finally, we obtained 15.13 g/L butanol and 24.37 g/L ABE at the high specific butanol production rate of 0.34 g/(g h) using pH-stat co-feeding method. Thus, in this study, we established a high ABE production system using glucose and acetate as co-substrates in a pH-stat co-feeding system with C. saccharoperbutylacetonicum N1-4..
46. Vichien Kitpreechavanich, Arisa Hayami, Anfal Talek, Clament Fui Seung Chin, Yukihiro Tashiro, Kenji Sakai, Simultaneous production of l-lactic acid with high optical activity and a soil amendment with food waste that demonstrates plant growth promoting activity, Journal of Bioscience and Bioengineering, 10.1016/j.jbiosc.2015.12.017, 122, 1, 105-110, 2016.07, A unique method to produce highly optically-active l-lactic acid and soil amendments that promote plant growth from food waste was proposed. Three Bacillus strains Bacillus subtilis KBKU21, B. subtilis N3-9 and Bacillus coagulans T27, were used. Strain KBKU21 accumulated 36.9 g/L l-lactic acid with 95.7% optical activity and 98.2% l-lactic acid selectivity when fermented at 43°C for 84 h in a model kitchen refuse (MKR) medium. Residual precipitate fraction (anaerobically-fermented MKR (AFM) compost) analysis revealed 4.60%, 0.70% and 0.75% of nitrogen (as N), phosphorous (as P2O5), and potassium (as K2O), respectively. Additionally, the carbon to nitrogen ratio decreased from 13.3 to 10.6. AFM compost with KBKU21 promoted plant growth parameters, including leaf length, plant height and fresh weight of Brassica rapa (Komatsuna), than that by chemical fertilizers or commercial compost. The concept provides an incentive for the complete recycling of food waste, contributing towards a sustainable production system..
47. Hongzhi Ma, Jian Yang, Yan Jia, Qunhui Wang, Yukihiro Tashiro, Kenji Sonomoto, Stillage reflux in food waste ethanol fermentation and its by-product accumulation, Bioresource Technology, 10.1016/j.biortech.2016.02.127, 209, 254-258, 2016.06, Raw materials and pollution control are key issues for the ethanol fermentation industry. To address these concerns, food waste was selected as fermentation substrate, and stillage reflux was carried out in this study. Reflux was used seven times during fermentation. Corresponding ethanol and reducing sugar were detected. Accumulation of by-products, such as organic acid, sodium chloride, and glycerol, was investigated. Lactic acid was observed to accumulate up to 120 g/L, and sodium chloride reached 0.14 mol/L. Other by-products did not accumulate. The first five cycles of reflux increased ethanol concentration, which prolonged fermentation time. Further increases in reflux time negatively influenced ethanol fermentation. Single-factor analysis with lactic acid and sodium chloride demonstrated that both factors affected ethanol fermentation, but lactic acid induced more effects..
48. Noor-Azira Abdul-Mutalib, Syafinaz Amin Nordin, Malina Osman, Ahmad Muhaimin Roslan, Natsumi Ishida, KENJI SAKAI, Yukihiro Tashiro, KOSUKE TASHIRO, Toshinari Maeda, Yoshihito Shirai, The prevalence of foodborne pathogenic bacteria on cutting boards and their ecological relationship with background biota, AIMS Microbiology, doi: 10.3934/microbiol.2016.2.138, 2, 2, 138-151, 2016.05.
49. Mohamed Ali Sayed Mohamed Abdelrahman, Yukihiro Tashiro, Takeshi Zendo, Kenji Sakai, Kenji Sonomoto, Highly efficient L-lactic acid production from xylose in cell recycle continuous fermentation using Enterococcus mundtii QU 25, RSC Advances, 10.1039/c5ra27579b, 6, 21, 17659-17668, 2016.01, A few strains of lactic acid bacteria metabolise xylose into optically pure L-lactic acid (LA). This study achieved an effective homofermentative cell recycle continuous fermentation of xylose to L-LA with high concentration, productivity, and yield using Enterococcus mundtii QU 25. In conventional continuous fermentation, the optimal xylose concentration in the feeding solution is 50 g L-1, and the optimal dilution rate is 0.15 h-1. Continuous fermentation with cell recycling using a microfiltration membrane module produced an L-LA concentration of 32.3 g L-1 with a yield of 0.789 g g-1 and a productivity of 5.33 g L-1 h-1. Controlling pH and optimising the feeding medium were important for achieving a high L-LA yield with strain QU 25. Using corn steep liquor-containing medium at pH 6.2, a maximum L-LA concentration, yield and productivity were achieved at 41.0 g L-1, 1.01 g g-1, and 6.15 g L-1 h-1, respectively. This study is the first to report on continuous fermentation with cell recycling for lactic acid production from xylose..
50. Nao Murakami, Mana Oba, Mariko Iwamoto, Yukihiro Tashiro, Takuya Noguchi, Kaori Bonkohara, Mohamed Ali Sayed Mohamed Abdelrahman, Takeshi Zendo, Mitsuya Shimoda, Kenji Sakai, Kenji Sonomoto, L-Lactic acid production from glycerol coupled with acetic acid metabolism by Enterococcus faecalis without carbon loss, Journal of Bioscience and Bioengineering, 10.1016/j.jbiosc.2015.05.009, 121, 1, 89-95, 2016.01, Glycerol is a by-product in the biodiesel production process and considered as one of the prospective carbon sources for microbial fermentation including lactic acid fermentation, which has received considerable interest due to its potential application. Enterococcus faecalis isolated in our laboratory produced optically pure l-lactic acid from glycerol in the presence of acetic acid. Gas chromatography-mass spectrometry analysis using [1, 2-13C2] acetic acid proved that the E. faecalis strain QU 11 was capable of converting acetic acid to ethanol during lactic acid fermentation of glycerol. This indicated that strain QU 11 restored the redox balance by oxidizing excess NADH though acetic acid metabolism, during ethanol production, which resulted in lactic acid production from glycerol. The effects of pH control and substrate concentration on lactic acid fermentation were also investigated. Glycerol and acetic acid concentrations of 30 g/L and 10 g/L, respectively, were expected to be appropriate for lactic acid fermentation of glycerol by strain QU 11 at a pH of 6.5. Furthermore, fed-batch fermentation with 30 g/L glycerol and 10 g/L acetic acid wholly exhibited the best performance including lactic acid production (55.3 g/L), lactic acid yield (0.991 mol-lactic acid/mol-glycerol), total yield [1.08 mol-(lactic acid and ethanol)]/mol-(glycerol and acetic acid)], and total carbon yield [1.06 C-mol-(lactic acid and ethanol)/C-mol-(glycerol and acetic acid)] of lactic acid and ethanol. In summary, the strain QU 11 successfully produced lactic acid from glycerol with acetic acid metabolism, and an efficient fermentation system was established without carbon loss..
51. Ming Gao, Hong Zhi Ma, Wei Su, Miao Yu, Yukihiro Tashiro, Qun Hui Wang, Effects of distillery waste recycling on open ethanol fermentation from kitchen garbage and technological enhancement, Zhongguo Huanjing Kexue/China Environmental Science, 35, 12, 3721-3727, 2015.12, Based on the previous studies, in order to reduce the distillery waste form ethanol fermentation, the distillery wastewater of ethanol production from kitchen garbage was recycled in this study. Particularly, the accumulation of the by-product during the fermentation and their effects were investigated. The results indicated that ethanol fermentation was inhibited obviously by full-recycling distillery wastewater without treatment. After 4times full-recycling, ethanol production was decreased from 28.4 g/L to 2.56 g/L. With the increasing recycling times, lactic acid, SS, DS and salinity were accumulated to 5.45, 64.7, 99.5 and 12.3 g/L, respectively. In order to improve the recycle times, 2/3 partial-recycling mode and flocculation full-recycling mode were utilized. During 7times of distillery wastewater recycling, the ethanol productions maintained at the range of 25.5~35.5 g/L for 2/3 partial-recycling mode. While for flocculation full-recycling mode, the ethanol production maintained at the range of 12.2~32.4 g/L. 2/3 partial-recycling mode was superior to flocculation full-recycling mode. In future, the combination of the two recycling methods should be considered for further improving the distillery wastewater recycling system..
52. Eiji Nishi, Yukihiro Tashiro, Kenji Sakai, Discrimination among individuals using terminal restriction fragment length polymorphism profiling of bacteria derived from forensic evidence, Journal of legal medicine, 10.1007/s00414-014-1092-z, 129, 3, 425-433, 2015.05, DNA typing from forensic evidence is commonly used to identify individuals. However, when the quantity of the forensic evidence is insufficient, successful identification using DNA typing is impossible. Such evidence may also contain DNA from bacteria that occur naturally on the skin. In this study, we aimed to establish a profiling method using terminal restriction fragment length polymorphisms (T-RFLPs) of the amplified bacterial 16S ribosomal RNA (rRNA) gene. First, the extraction and digestion processes were investigated, and the T-RFLP profiling method using the 16S rRNA gene amplicon was optimized. We then used this method to compare the profiles of bacterial flora from the hands of 12 different individuals. We found that the T-RFLP profiles from one person on different days displayed higher similarity than those between individuals. In a principal component analysis (PCA), T-RFLPs from each individual were closely clustered in 11 out of 12 cases. The clusters could be distinguished from each other, even when the samples were collected from different conditions. No major change of the profile was observed after six months except in two cases. When handprints on glass plates were compared, 11 of 12 individuals were assigned to a few clusters including the cluster corresponding to the correct individual. In conclusion, a method for reproducible T-RFLP profiling of bacteria from trace amounts of handprints was established. The profiles were obtained for particular individuals clustered in PCA and were experimentally separable from other individuals in most cases. This technique could provide useful information for narrowing down a suspect in a criminal investigation..
53. Noor Azira Abdul-Mutalib, Syafinaz Amin Nordin, Malina Osman, Natsumi Ishida, Kosuke Tashiro, Kenji Sakai, Yukihiro Tashiro, Toshinari Maeda, Yoshihito Shirai, Pyrosequencing analysis of microbial community and food-borne bacteria on restaurant cutting boards collected in Seri Kembangan, Malaysia, and their correlation with grades of food premises, International Journal of Food Microbiology, 10.1016/j.ijfoodmicro.2015.01.022, 200, 57-65, 2015.05, This study adopts the pyrosequencing technique to identify bacteria present on 26 kitchen cutting boards collected from different grades of food premises around Seri Kembangan, a city in Malaysia. Pyrosequencing generated 452,401 of total reads of OTUs with an average of 1.4×107 bacterial cells/cm2. Proteobacteria, Firmicutes and Bacteroides were identified as the most abundant phyla in the samples. Taxonomic richness was generally high with >1000 operational taxonomic units (OTUs) observed across all samples. The highest appearance frequencies (100%) were OTUs closely related to Enterobacter sp., Enterobacter aerogenes, Pseudomonas sp. and Pseudomonas putida. Several OTUs were identified most closely related to known food-borne pathogens, including Bacillus cereus, Cronobacter sakazaki, Cronobacter turisensis, Escherichia coli, E. coli O157:H7, Hafnia alvei, Kurthia gibsonii, Salmonella bongori, Salmonella enterica, Salmonella paratyphi, Salmonella tyhpi, Salmonella typhimurium and Yersinia enterocolitica ranging from 0.005% to 0.68% relative abundance. The condition and grade of the food premises on a three point cleanliness scale did not correlate with the bacterial abundance and type. Regardless of the status and grades, all food premises have the same likelihood to introduce food-borne bacteria from cutting boards to their foods and must always prioritize the correct food handling procedure in order to avoid unwanted outbreak of food-borne illnesses..
54. Mohamed Ali Sayed Mohamed Abdelrahman, Yaotian Xiao, Yukihiro Tashiro, Ying Wang, Takeshi Zendo, Kenji Sakai, Kenji Sonomoto, Fed-batch fermentation for enhanced lactic acid production from glucose/xylose mixture without carbon catabolite repression, Journal of Bioscience and Bioengineering, 10.1016/j.jbiosc.2014.07.007, 119, 2, 153-158, 2015.02, There has been tremendous growth in the production of optically pure l-lactic acid from lignocellulose-derived sugars. In this study, Enterococcus mundtii QU 25 was used to ferment a glucose/xylose mixture to l-lactic acid. Maintenance of the xylose concentration at greater than 10g/L achieved homo-lactic acid fermentation and reduced the formation of byproducts. Furthermore, carbon catabolite repression (CCR) was avoided by maintaining the glucose concentration below 25g/L; therefore, initial concentrations of 25g/L glucose and 50g/L xylose were selected. Supplementation with 5g/L yeast extract enhanced the maximum xylose consumption rate and consequently increased lactic acid production and productivity. Finally, a 129g/L lactic acid without byproducts was obtained with a maximum lactic acid productivity of 5.60g/(L·h) in fed-batch fermentation with feeding a glucose/xylose mixture using ammonium hydroxide as the neutralizing agent. These results indicate a potential for lactic acid production from glucose and xylose as the main components of lignocellulosic biomasses..
55. Jin Zheng, Yukihiro Tashiro, Qunhui Wang, Kenji Sakai, Kenji Sonomoto, Feasibility of acetone-butanol-ethanol fermentation from eucalyptus hydrolysate without nutrients supplementation, Applied Energy, 10.1016/j.apenergy.2014.11.037, 140, 113-119, 2015.02, The economic feasibility of acetone-butanol-ethanol (ABE) fermentation is greatly affected by the type of raw material used. The easy availability of eucalyptus from marginal environments is an alternative feedstock for use as raw material to reduce the production cost. In this study, hydrolyzed eucalyptus was used for ABE production without any nutrients supplementation. Increasing the solid concentration in the eucalyptus slurry from 6.7% (w-dry matter/. v) to 25% led to an increase in the initial glucose concentration from 33.7. g/L to 86.7. g/L after enzymatic hydrolysis. Dosed cellulases not only hydrolyzed cellulose but also supplied nitrogen source for ABE producing strain. However, ABE production from the obtained hydrolysate decreased when the solid concentration was increased to more than 10%. The maximum ABE of 12.3. g/L was obtained at 10% solid concentration, with an initial glucose concentration of approximately 40. g/L. In addition, the fermentation capability of eucalyptus hydrolysate was found to be improved by diluting the hydrolysate, which prevented inhibition by substrate and fermentation inhibitors. Finally, ABE concentration was improved to 13.1. g/L by diluting the hydrolysate from the initial solid concentration of 25% to an initial glucose concentration of 45. g/L, which resulted in ABE productivity of 0.109. g/L/h and ABE yield of 0.413. g/g. Thus, the high ABE production from eucalyptus makes it a potential feedstock for biofuel production..
56. Pramod Poudel, Yukihiro Tashiro, Hirokuni Miyamoto, Hisashi Miyamoto, Yuki Okugawa, Kenji Sakai, Direct starch fermentation to l-lactic acid by a newly isolated thermophilic strain, Bacillus sp. MC-07, Journal of Industrial Microbiology and Biotechnology, 10.1007/s10295-014-1534-0, 42, 1, 143-149, 2015.01, A newly isolated Bacillus sp. MC-07 showed 99.2 % 16S rRNA gene sequence similarity with the Bacillus thermoamylovorans LMG 18084T. It demonstrated optimum and maximum growth temperatures of 50 and 62 °C, respectively. The ability of MC-07 to produce optically pure l-lactic acid via direct fermentation of starch without enzymatic hydrolysis was investigated at different pH values (6.0–8.0) by intermittent adjustments every 12 h. During batch fermentation in mineral salt medium containing 0.001 % yeast extract at pH 7.0, 20 g/L of soluble starch was utilized to produce 16.6 g/L l-lactic acid at 50 °C within 24 h of fermentation, with 100 % optical purity, 92.1 % lactic acid selectivity, and an l-lactic acid yield of 0.977 g/g. Direct starch fermentation at pHs 6.0, 6.5, 7.5, and 8.0 resulted in considerably lower concentrations of lactic acid than did at pH 7.0. Compared with B. thermoamylovorans LMG 18084T, the ability of strain MC-07 to produce l-lactic acid was superior..
57. Mohamed Ali Sayed Mohamed Abdelrahman, Yukihiro Tashiro, Takeshi Zendo, Kenji Sakai, Kenji Sonomoto, Enterococcus faecium QU 50
A novel thermophilic lactic acid bacterium for high-yield l-lactic acid production from xylose, FEMS Microbiology Letters, 10.1093/femsle/fnu030, 362, 2, 2015.01, Production of optically pure lactic acid from lignocellulosic material for commercial purposes is hampered by several difficulties, including heterofermentation of pentose sugars and high energy consumption by mesophilic lactic acid bacteria. Here, we report a novel lactic acid bacterium, strain QU 50, that has the potential to produce optically pure l-lactic acid (≥99.2%) in a homofermentative manner from xylose under thermophilic conditions. Strain QU 50 was isolated from Egyptian fertile soil and identified as Enterococcus faecium QU 50 by analyzing its sugar fermentation pattern and 16S rRNA gene sequence. Enterococcus faecium QU 50 fermented xylose efficiently to produce lactic acid over wide pH (6.0-10.0) and temperature ranges (30-52°C), with a pH of 6.5 and temperature of 50°C being optimal. To our knowledge, this is the first report of homofermentative lactic acid production from xylose by a thermophilic lactic acid bacterium..
58. Ming Gao, Yukihiro Tashiro, Tsuyoshi Yoshida, Jin Zheng, Qunhui Wang, Kenji Sakai, Kenji Sonomoto, Metabolic analysis of butanol production from acetate in Clostridium saccharoperbutylacetonicum N1-4 using 13C tracer experiments, RSC Advances, 10.1039/c4ra09571e, 5, 11, 8486-8495, 2014.12, During acetone-butanol-ethanol (ABE) fermentation by clostridia, acetate is reutilised for butanol production. In this study, we investigated the characteristics of ABE production from acetate and analysed the metabolism of exogenously added acetate by Clostridium saccharoperbutylacetonicum N1-4. Supplementation of 4 g L-1 exogenous acetate, to media containing glucose, increased not only concentrations of butanol (48.3%) and acetone (90.5%), but also the ratio of acetone to butanol (27.1%), which suggested that acetate addition altered the metabolic flux. Acetate could not be metabolised in the absence of glucose, thus glycolysis appeared to be necessary for acetate utilisation. In order to clarify the metabolism of exogenous acetate, 13C tracer experiments were performed by supplementing [1,2-13C2] acetate in a culture broth. Based on the results of gas chromatography-mass spectroscopy analysis, we first confirmed both butanol and acetone formation from acetate. Further, the acetate-to-butanol efficiency will significantly decrease when more acetate than 2-4 g L-1 is added to the fermentation, while acetate-to-acetone efficiency may remain high (up to a ratio of 2 mol acetate per 1 mol glucose fed). Moreover, the culture supplemented with acetate exhibited an increase in conversion efficiency of glucose to butanol and acetone, from 0.196% to 19.5% and from 0 to 7.64%, respectively, even during acidogenesis. Thus, we first revealed quantitatively that acetate addition induced solvent production during the early growth phase, and increased metabolic flux to acetone and butanol production from both acetate and glucose..
59. Pramod Poudel, Hirokuni Miyamoto, Hisashi Miyamoto, Yuki Okugawa, Yukihiro Tashiro, Kenji Sakai, Thermotolerant Bacillus kokeshiiformis sp. nov. isolated from marine animal resources compost, International Journal of Systematic and Evolutionary Microbiology, 10.1099/ijs.0.059329-0, 64, PART 8, 2668-2674, 2014.08, A novel Gram-staining-positive, endospore-forming, rod-shaped, facultatively anaerobic, thermotolerant bacterium, designated strain MO-04T, was isolated from a marine animal resources (MAR) compost. The 16S rRNA gene sequence of strain MO-04T showed 99.4 % similarity with Bacillus thermolactis R-6488T, 94.1 % similarity with Bacillus thermoamylovorans CNCM I-1378T, 93.3 % similarity with Bacillus humi LMG 22167T, 93.2 % similarity with Bacillus niacini IFO 15566T and the similarities with other species were less than 93 %. DNA-DNA relatedness between strain MO-04Tand B. thermolactis DSM 23332T was 45 %. The DNA G+C content of strain MO-04T was 33.4 mol%, comparatively lower than that of B. thermolactis R-6488T (35.0 mol%). Strain MO-04T grew at 35-61 °C (optimum 50 °C), pH 4.5-9.0 (optimum pH 7.2) and tolerated up to 8.0 % (w/v) NaCl (optimum 2 %). The MO-04T cell wall peptidoglycan type was meso-2, 6-diaminopimelic acid, and the major fatty acids were C16: 1, C14: 1, C17: 0 and C17: 1. The major polar lipids were represented by diphosphatidylglycerol and phosphatidylglycerol and two unidentified phospholipids. The analysed polyphasic data presented here clearly indicate that the isolate MO-04T is considered to represent a novel species within the genus Bacillus for which the name Bacillus kokeshiiformissp. nov. is proposed. The type strain of B. kokeshiiformis is MO-04T (= JCM 19325T = KCTC 33163T)..
60. Ying Wang, Mohamed Ali Sayed Mohamed Abdelrahman, Yukihiro Tashiro, Yaotian Xiao, Takeshi Zendo, Kenji Sakai, Kenji Sonomoto, L-(+)-Lactic acid production by co-fermentation of cellobiose and xylose without carbon catabolite repression using Enterococcus mundtii QU 25, RSC Advances, 10.1039/c4ra02764g, 4, 42, 22013-22021, 2014.05, The use of lignocellulosic biomass for the production of optically pure lactic acid remains challenging because it requires efficient utilisation of mixed sugars without carbon catabolite repression (CCR). Enterococcus mundtii QU 25, a novel l-lactic acid-producing strain, was used in this study to ferment mixed sugars. This strain exhibited apparent CCR in a glucose-xylose mixture; however, replacement of glucose by cellobiose (cellobiose-xylose mixture) led to simultaneous consumption of both sugars without CCR. The production of lactic acid and activity of enzymes related to xylose metabolism were also investigated. Xylose isomerase and xylulokinase specific activity in cellobiose-xylose grown cells was three times higher than that in glucose-xylose grown cells. The addition of yeast extract and ammonium hydroxide effectively improved sugar utilisation and cell growth. Under the optimal conditions with simulated lignocellulosic hydrolysates, a high l-lactic acid concentration (up to 163 g L-1) was produced with a yield of 0.870 g g-1 and maximum productivity of 7.21 g L-1 h-1 without CCR in the fed-batch fermentation. Thus, we could establish rapid and simultaneous consumption of hexose and pentose sugars by using a lactic acid bacterium strain, which significantly increased production of high-purity l-lactic acid. This journal is.
61. Saowanit Tongpim, Ratchanu Meidong, Pramod Poudel, Satoshi Yoshino, Yuki Okugawa, Yukihiro Tashiro, Masayuki Taniguchi, Kenji Sakai, Isolation of thermophilic l-lactic acid producing bacteria showing homo-fermentative manner under high aeration condition, Journal of Bioscience and Bioengineering, 10.1016/j.jbiosc.2013.08.017, 117, 3, 318-324, 2014.03, By applying non-sterile open fermentation of food waste, various thermotolerant l-lactic acid-producing bacteria were isolated and identified. The predominant bacterial isolates showing higher accumulation of l-lactic acid belong to 3 groups of Bacillus coagulans, according to their 16S rRNA gene sequence similarities. B.coagulans strains M21 and M36 produced high amounts of l-lactic acid of high optical purity and lactic acid selectivity in model kitchen refuse medium and glucose-yeast extract-peptone medium. Other thermotolerant isolates resembling to Bacillus humi, B. ruris, B.subtilis, B. niacini and B. soli were also identified. These bacteria produced low amounts of l-lactic acid of more than 99% optical purity. All isolated strains showed the highest growth rate at temperatures around 55-60°C. They showed unique responses to various oxygen supply conditions. The majority of isolates produced l-lactic acid at a low overall oxygen transfer coefficient (KLa); however, acetic acid was produced instead of l-lactic acid at a high KLa. B.coagulans M21 was the only strain that produced high, consistent, and reproducible amounts of optically pure l-lactic acid (>99% optical purity) under high and low KLa conditions in a homo-fermentative manner..
62. Takuya Noguchi, Yukihiro Tashiro, Tsuyoshi Yoshida, Jin Zheng, Kenji Sakai, Kenji Sonomoto, Efficient butanol production without carbon catabolite repression from mixed sugars with Clostridium saccharoperbutylacetonicum N1-4, Journal of Bioscience and Bioengineering, 10.1016/j.jbiosc.2013.05.030, 116, 6, 716-721, 2013.12, Acetone-butanol-ethanol (ABE) fermentation using Clostridium saccharoperbutylacetonicum N1-4 and mixed sugars containing cellobiose and xylose was studied to establish efficient butanol production process without carbon catabolite repression (CCR). Although batch culture with glucose and xylose exhibited apparent CCR, we achieved simultaneous consumption of cellobiose and xylose. Moreover, preculture of the N1-4 strain with xylose yielded maximum butanol and solvent concentrations (16 and 23g/L, respectively). Thus, we succeeded in ABE fermentation with mixed sugars of hexose and pentose, without CCR, by using wild-type ABE-producing clostridia. We also investigated the effect of various ratios of cellobiose and xylose on the fermentation process and yield. Increasing initial xylose concentration improved butanol and solvent concentrations and maximum xylose consumption rate. Fed-batch culture with cellobiose and xylose showed rapid and simultaneous sugar consumption and improved maximum consumption rate of both sugars..
63. Pramod Poudel, Yukihiro Tashiro, KENJI SAKAI, FEED-BACK ISOLATION AND IDENTIFICATION OF THERMO-TOLERANT BACTERIA WITHIN MIXED CULTURE SYSTEM, Proceeding of The 7th International Symposium on the East Asian Environmental Problems (EAEP2013), 176-180, 2013.11.
64. Huijun Cheng, TOSHIHIKO KII, KOSUKE KANDA, Yukihiro Tashiro, KENJI SAKAI, EVALUATION OF HYDROLYZING SYSTEM OF HUMAN EXCRETA ON SELF-HEATING AEROBIC TREATMENT, Proceeding of The 7th International Symposium on the East Asian Environmental Problems (EAEP2013), 190-194, 2013.11.
65. Yukihiro Tashiro, Hiroko Matsumoto, Hirokuni Miyamoto, Yuki Okugawa, Poudel Pramod, Hisashi Miyamoto, Kenji Sakai, A novel production process for optically pure l-lactic acid from kitchen refuse using a bacterial consortium at high temperatures, Bioresource Technology, 10.1016/j.biortech.2013.07.102, 146, 672-681, 2013.10, We investigated l-lactic acid production in static batch fermentation of kitchen refuse using a bacterial consortium from marine-animal-resource (MAR) composts at temperatures ranging from 30 to 65°C. At relatively low temperatures butyric acid accumulated, whereas at higher temperatures l-lactic acid was produced. In particular, fermentation at 50°C produced 34.5gL-1 l-lactic acid with 90% lactic acid selectivity and 100% optical purity. Denaturing gradient gel electrophoresis indicated that dominant bacteria present in the original MAR composts diminished rapidly and Bacillus coagulans strains became the dominant contributors to l-lactic acid production at 45, 50 and 55°C. This is the first report of the achievement of 100% optical purity of l-lactic acid using a bacterial consortium..
66. Mohamed Ali Sayed Mohamed Abdelrahman, Yukihiro Tashiro, Takeshi Zendo, Kenji Sonomoto, Improved lactic acid productivity by an open repeated batch fermentation system using Enterococcus mundtii QU 25, RSC Advances, 10.1039/c3ra00078h, 3, 22, 8437-8445, 2013.06, Decreasing the production cost of polymer-grade lactic acid is a challenge that the polylactic acid industry must surmount to be competitive with producers of petrochemical-derived plastics. In this study, we aimed to improve lactic acid productivity by investigating different fermentation systems. Enterococcus mundtii QU 25, previously reported by our group as a thermotolerant lactic acid bacterium, homofermentatively metabolizes glucose with the production of high optically pure l-lactic acid. The strain showed high lactic acid concentration and yield by controlled pH (7.0) and at a high temperature (43 °C). In a batch fermentation system, the optimal initial glucose concentration was 100 g L-1, at which high cell mass was achieved with production of 82.4 g L-1 of lactic acid at yield of 0.858 g g-1 glucose consumed. However, the productivity was approximately 2.0 g L-1 h-1. Subsequently, open repeated batch or fed-batch fermentation with recycled cells of the previous fermentation was conducted for 11 runs to enhance the productivity. As a result, lactic acid productivity was enhanced-up to 5.5-fold higher than that of the conventional batch culture, and fermentation was completed within 6 h with almost the same yield (0.761-0.832 g g -1 glucose consumed) and lactic acid concentration (81.6-84.5 g L-1). Up to 132 g L-1 lactic acid at yield of 0.853 g g-1 glucose consumed and productivity of 6.99 g L-1 h -1 were obtained in open repeated fed-batch fermentation. This indicates that strain QU 25 has the potential for industrial-scale production of lactic acid due to its high productivity, high yield of substrate conversion, and high final concentration of lactic acid produced under non-sterile conditions..
67. Jin Zheng, Yukihiro Tashiro, Tsuyoshi Yoshida, Ming Gao, Qunhui Wang, Kenji Sonomoto, Continuous butanol fermentation from xylose with high cell density by cell recycling system, Bioresource Technology, 10.1016/j.biortech.2012.11.066, 129, 360-365, 2013.02, A continuous butanol production system with high-density Clostridium saccharoperbutylacetonicum N1-4 generated by cell recycling was established to examine the characteristics of butanol fermentation from xylose. In continuous culture without cell recycling, cell washout was avoided by maintaining pH>5.6 at a dilution rate of 0.26h-1, indicating pH control was critical to this experiment. Subsequently, continuous culture with cell recycling increased cell concentration to 17.4gL-1, which increased butanol productivity to 1.20gL-1h-1 at a dilution rate of 0.26h-1 from 0.529gL-1h-1 without cell recycling. The effect of dilution rates on butanol production was also investigated in continuous culture with cell recycling. Maximum butanol productivity (3.32gL-1h-1) was observed at a dilution rate of 0.78h-1, approximately 6-fold higher than observed in continuous culture without cell recycling (0.529gL-1h-1)..
68. Nana Yokochi, Shigemitsu Tanaka, Kouichi Matsumoto, Hirotaka Oishi, Yukihiro Tashiro, Yu Yoshikane, Mikio Nakashima, Kohzo Kanda, Genta Kobayashi, Distribution of Virulence Markers among Vibrio vulnificus Isolates of Clinical and Environmental Origin and Regional Characteristics in Japan, PLoS One, 10.1371/journal.pone.0055219, 8, 1, 2013.01, Background: Vibrio vulnificus is an opportunistic human pathogen that is widely distributed in estuarine environments and is capable of causing necrotizing fasciitis and sepsis. In Japan, based on epidemiological research, the incidences of V. vulnificus were concentrated in Kyusyu, mainly in coastal areas of the Ariake Sea. To examine the virulence potential, various genotyping methods have recently been developed. This study aimed to investigate the distribution of virulence markers among V. vulnificus isolates of clinical and environmental origin in three coastal areas with different infection incidences and to determine whether these isolates have the siderophore encoding gene viuB. Methodology/Principal Findings: We examined the distribution of genotypes of the 16S ribosomal ribonucleic acid (rRNA) gene, vvhA, vcg, and capsular polysaccharide (CPS), and the presence of viuB in 156 isolates collected from patients and environmental samples in Japan. The environmental samples were collected from three coastal areas: the Ariake Sea, Ise & Mikawa Bay, and Karatsu Bay. The results showed disparity in the ratios of genotypes depending on the sample origins. V. vulnificus isolates obtained from patients were classified into the clinical type for all genotypes. In the environmental isolates, the ratios of the clinical type for genotypes of the 16S rRNA gene, vvhA, and vcg were in the order of the Ariake Sea>Ise & Mikawa Bay>Karatsu Bay. Meanwhile, CPS analysis showed no significant difference. Most isolates possessed viuB. Conclusions: Many V. vulnificus belonging to the clinical type existed in the Ariake Sea. Three coastal areas with different infection incidences showed distinct ratios of genotypes. This may indicate that the distribution of clinical isolates correlates with the incidence of V. vulnificus infection..
69. Jianguo Liu, Qunhui Wang, Shuang Wang, Xiaohong Sun, Hongzhi Ma, Yukihiro Tashiro, Effects of pretreatment on the microbial community and l-lactic acid production in vinasse fermentation, Journal of Biotechnology, 10.1016/j.jbiotec.2012.08.014, 164, 2, 260-265, 2012.12, Microwave-alkali and steam-alkali coupled pretreatments were carried out to improve the yield and optical purity of l-lactic acid produced using vinasse fermentation. Lactobacillus casei was inoculated into the system to initiate fermentation. Polymerase chain reaction denaturing gradient gel electrophoresis was used to analyze the microbial community during fermentation with and without the pretreatments. The original bacterial genus in vinasse was essentially inactivated, whereas L. casei became the dominant genus after 24. h of fermentation. The system subjected to microwave-alkali coupled pretreatment released more reducing sugars and produced more lactic acid (up to 30.32. g/L), which is twice that without pretreatment. In addition, the proportion of lactic acid in the organic acids also increased. The optical purity of the l-lactic acid produced under the microwave-alkali coupled pretreatment reached 91%, which is 2% higher than that under the steam-alkali coupled pretreatment and 7% higher than that under the control conditions. Therefore, the microwave-alkali coupled pretreatment is an effective method for the highly efficient bioconversion of vinasse into bioenergy..
70. Tsuyoshi Yoshida, Yukihiro Tashiro, Kenji Sonomoto, Novel high butanol production from lactic acid and pentose by Clostridium saccharoperbutylacetonicum, Journal of Bioscience and Bioengineering, 10.1016/j.jbiosc.2012.06.001, 114, 5, 526–530, 2012.11.
71. Shigemitsu Tanaka, Yukihiro Tashiro, Genta Kobayashi, Toru Ikegami, Hideyuki Negishi, Keiji Sakaki, Membrane-assisted extractive butanol fermentation by Clostridium saccharoperbutylacetonicum N1-4 with 1-dodecanol as the extractant, Bioresource Technology, 10.1016/j.biortech.2012.03.096, 116, 448-452, 2012.07, A polytetrafluoroethylene (PTFE) membrane was used in membrane-assisted extractive (MAE) fermentation of acetone-butanol-ethanol (ABE) by Clostridium saccharoperbutylacetonicum N1-4. The growth inhibition effects of 1-dodecanol, which has a high partition coefficient for butanol, can be prevented by employing 1-dodecanol as an extractant when using a PTFE membrane. Compared to conventional fermentation, MAE-ABE fermentation with 1-dodecanol decreased butanol inhibition and increased glucose consumption from 59.4 to 86.0g/L, and total butanol production increased from 16.0 to 20.1g/L. The maximum butanol production rate increased from 0.817 to 0.979g/L/h. The butanol productivity per membrane area was remarkably high with this system, i.e., 78.6g/L/h/m 2. Therefore, it is expected that this MAE fermentation system can achieve footprint downsizing..
72. Shun ichi Baba, Yukihiro Tashiro, Hideaki Shinto, Kenji Sonomoto, Development of high-speed and highly efficient butanol production systems from butyric acid with high density of living cells of Clostridium saccharoperbutylacetonicum, Journal of Biotechnology, 10.1016/j.jbiotec.2011.06.004, 157, 4, 605-612, 2012.02, Living cells are alive and have the butanol-producing ability but not much proliferation under nitrogen source-limited condition. We investigated various butanol production systems with high density of living cells of Clostridium saccharoperbutylacetonicum N1-4 supplemented with methyl viologen (MV) as an electron carrier and nutrient dosing for activity regeneration. In continuous butanol production with high density of living cells, butanol yield was drastically increased from 0.365C-mol/C-mol with growing cells to 0.528C-mol/C-mol at a dilution rate of 0.85h -1, being increased with the butanol to total solvent ratio. This yield was increased to 0.591C-mol/C-mol by adding 0.01mM MV. MV addition increased not only butanol yield but also butanol concentration and productivity as compared to those without MV addition. However, living cells lost their activity with incubation time, which lowered the operational stability of the system. Therefore, to maintain constant stability, activity regeneration was carried out with high density of living cells and MV. This system produced butanol at high concentration (9.40gl -1) and productivity (7.99gl -1h -1) for approximately 100h with maintenance of considerably high yield of butanol (0.686C-mol/C-mol). Thus, we established a high-speed and highly efficient butanol production system..
73. Analysis of bacterial community structures in coastal sediments in the Ariake Sea.
74. Mohamed Ali Sayed Mohamed Abdelrahman, Yukihiro Tashiro, Takeshi Zendo, Katsuhiro Hanada, Keisuke Shibata, Kenji Sonomoto, Efficient homofermentative L-(+)-Lactic acid production from xylose by a novel lactic acid bacterium, Enterococcus mundtii QU 25, Applied and Environmental Microbiology, 10.1128/AEM.02076-10, 77, 5, 1892-1895, 2011.03, Enterococcus mundtii QU 25, a newly isolated lactic acid bacterium, efficiently metabolized xylose into L-lactate. In batch fermentations, the strain produced 964 mM L-(+)-lactate from 691 mM xylose, with a yield of 1.41 mol/mol xylose consumed and an extremely high optical purity of ≥99.9% without acetate production..
75. Yukihiro Tashiro, Wataru Kaneko, Yanqi Sun, Keisuke Shibata, Kentaro Inokuma, Takeshi Zendo, Kenji Sonomoto, Continuous D-lactic acid production by a novelthermotolerant Lactobacillus delbrueckii subsp. lactis QU 41, Applied Microbiology and Biotechnology, 10.1007/s00253-010-3011-7, 89, 6, 1741-1750, 2011.03, We isolated and characterized a d-lactic acid-producing lactic acid bacterium (d-LAB), identified as Lactobacillus delbrueckii subsp. lactis QU 41. When compared to Lactobacillus coryniformis subsp. torquens JCM 1166T and L. delbrueckii subsp. lactis JCM 1248T, which are also known as d-LAB, the QU 41 strain exhibited a high thermotolerance and produced d-lactic acid at temperatures of 50°C and higher. In order to optimize the culture conditions of the QU 41 strain, we examined the effects of pH control, temperature, neutralizing reagent, and initial glucose concentration on d-lactic acid production in batch cultures. It was found that the optimal production of 20.1 g/l d-lactic acid was acquired with high optical purity (>99.9% of d-lactic acid) in a pH 6.0-controlled batch culture, by adding ammonium hydroxide as a neutralizing reagent, at 43°C in MRS medium containing 20 g/l glucose. As a result of product inhibition and low cell density, continuous cultures were investigated using a microfiltration membrane module to recycle flow-through cells in order to improve d-lactic acid productivity. At a dilution rate of 0.87 h-1, the high cell density continuous culture exhibited the highest d-lactic acid productivity of 18.0 g/l/h with a high yield (ca. 1.0 g/g consumed glucose) and a low residual glucose (
76. Mohamed Ali Sayed Mohamed Abdelrahman, Yukihiro Tashiro, Takeshi Zendo, Keisuke Shibata, Kenji Sonomoto, Isolation and characterisation of lactic acid bacterium for effective fermentation of cellobiose into optically pure homo l-(+)-lactic acid, Applied Microbiology and Biotechnology, 10.1007/s00253-010-2986-4, 89, 4, 1039-1049, 2011.02, Effective utilisation of cellulosic biomasses for economical lactic acid production requires a microorganism with potential ability to utilise efficiently its major components, glucose and cellobiose. Amongst 631 strains isolated from different environmental samples, strain QU 25 produced high yields of l-(+)-lactic acid of high optical purity from cellobiose. The QU 25 strain was identified as Enterococcus mundtii based on its sugar fermentation pattern and 16S rDNA sequence. The production of lactate by fermentation was optimised for the E. mundtii QU25 strain. The optimal pH and temperature for batch culturing were found to be 7.0°C and 43°C, respectively. E. mundtii QU 25 was able to metabolise a mixture of glucose and cellobiose simultaneously without apparent carbon catabolite repression. Moreover, under the optimised culture conditions, production of optically pure l-lactic acid (99.9%) increased with increasing cellobiose concentrations. This indicates that E. mundtii QU 25 is a potential candidate for effective lactic acid production from cellulosic hydrolysate materials..
77. Mohamed Ali Sayed Mohamed Abdelrahman, Takeshi Zendo, Kenji Sonomoto, Yukihiro Tashiro, Optimization of fermentation conditions for high L-lactic acid production from cellobiose by Entercoccus mundtii QU 25
Impact of pH control and temperature on cell growth and changes in metabolites, 2010 International Conference on Environmental Engineering and Applications, ICEEA 2010 ICEEA 2010 - 2010 International Conference on Environmental Engineering and Applications, Proceedings, 10.1109/ICEEA.2010.5596153, 307-311, 2010.09, Optimization of L-(+)-lactic acid production from cellobiose, one of the main cellulase inhibitors during saccharifaying process, was studied. Fermentation runs pH-controlled at 7.0 provided the highest lactic acid produced (18.6 g/L) and maximum lactic acid productivity (2.1 g/L/h) which were increased by 376% and 346%, respectively in comparison to non pH-controlled batches. Moreover, the maximum L-lactic acid yield and optical purity were obtained at pH 7.0 with 0.94 g/g and 100%, respectively. The optimum temperature was found to be 43°C, at which the lactic acid yield and maximum productivity were 1.0 g/g and 3.44 g/L/h, respectively. This study provides an encouraging means for economic production of optically pure L-lactic acid from pre-hydrolyzed cellulosic materials..
78. Mohamed Ali Sayed Mohamed Abdelrahman, Takeshi Zendo, Kenji Sonomoto, Yukihiro Tashiro, Development of sustainable society through efficient biotechnological production of optically active L-lactic acid from cellulose-derived sugars, 2010 International Conference on Environmental Engineering and Applications, ICEEA 2010 ICEEA 2010 - 2010 International Conference on Environmental Engineering and Applications, Proceedings, 10.1109/ICEEA.2010.5596150, 312-316, 2010.09, Effective utilization of cellulosic biomass as a feedstock for lactic acid production is still problematic due to high cost of saccharifying enzymes combined with feedback inhibition caused by final hydrolysis products, glucose and cellobiose. In this study we demonstrated that Enterococcus mundtii QU 25, a newly isolated lactic acid bacterium, is able to utilize cellobiose efficiently. In batch fermentations, 89.8 g/L of L-lactic acid was produced from 100 g/L cellobiose at yield of 91.3 (%) g/g-consumed sugar. Moreover, this strain capable of utilizing glucose/cellobiose mixture simultaneously for efficient production of L-lactic acid without apparent catabolite repression, thereby allowing complete utilization of all released sugars combined high L-lactic acid production yield..
79. Mugihito Oshiro, Katsuhiro Hanada, Yukihiro Tashiro, Kenji Sonomoto, Efficient conversion of lactic acid to butanol with pH-stat continuous lactic acid and glucose feeding method by Clostridium saccharoperbutylacetonicum, Applied Microbiology and Biotechnology, 10.1007/s00253-010-2673-5, 87, 3, 1177-1185, 2010.07, In order to achieve high butanol production by Clostridium saccharoperbutylacetonicum N1-4, the effect of lactic acid on acetone-butanol-ethanol fermentation and several fed-batch cultures in which lactic acid is fed have been investigated. When a medium containing 20 g/l glucose was supplemented with 5 g/l of closely racemic lactic acid, both the concentration and yield of butanol increased; however, supplementation with more than 10 g/l lactic acid did not increase the butanol concentration. It was found that when fed a mixture of lactic acid and glucose, the final concentration of butanol produced by a fed-batch culture was greater than that produced by a batch culture. In addition, a pH-controlled fed-batch culture resulted in not only acceleration of lactic acid consumption but also a further increase in butanol production. Finally, we obtained 15.5 g/l butanol at a production rate of 1.76 g/l/h using a fed-batch culture with a pH-stat continuous lactic acid and glucose feeding method. To confirm whether lactic acid was converted to butanol by the N1-4 strain, we performed gas chromatography-mass spectroscopy (GC-MS) analysis of butanol produced by a batch culture during fermentation in a medium containing [1,2,3-13C3] lactic acid as the initial substrate. The results of the GC-MS analysis confirmed the bioconversion of lactic acid to butanol..
80. Mugihito Oshiro, Hideaki Shinto, Yukihiro Tashiro, Noriko Miwa, Tatsuya Sekiguchi, Masahiro Okamoto, Ayaaki Ishizaki, Kenji Sonomoto, Kinetic modeling and sensitivity analysis of xylose metabolism in Lactococcus lactis IO-1, Journal of Bioscience and Bioengineering, 10.1016/j.jbiosc.2009.05.003, 108, 5, 376-384, 2009.11, We proposed a kinetic simulation model of xylose metabolism in Lactococcus lactis IO-1 that describes the dynamic behavior of metabolites using the simulator WinBEST-KIT. This model was developed by comparing the experimental time-course data of metabolites in batch cultures grown in media with initial xylose concentrations of 20.3-57.8 g/l with corresponding calculated data. By introducing the terms of substrate activation, substrate inhibition, and product inhibition, the revised model showed a squared correlation coefficient (r2) of 0.929 between the experimental time-course of metabolites and the calculated data. Thus, the revised model is assumed to be one of the best candidates for kinetic simulation describing the dynamic behavior of metabolites. Sensitivity analysis revealed that pyruvate flux distribution is important for higher lactate production. To confirm the validity of our kinetic model, the results of the sensitivity analysis were compared with enzyme activities observed during increasing lactate production by adding natural rubber serum powder to the xylose medium. The experimental results on pyruvate flux distribution were consistent with the prediction by sensitivity analysis..
81. Hideaki Shinto, Yukihiro Tashiro, Genta Kobayashi, Tatsuya Sekiguchi, Taizo Hanai, Yuki Kuriya, Masahiro Okamoto, Kenji Sonomoto, Kinetic study of substrate dependency for higher butanol production in acetone-butanol-ethanol fermentation, Process Biochemistry, 10.1016/j.procbio.2008.06.003, 43, 12, 1452-1461, 2008.12, A kinetic simulation model of acetone-butanol-ethanol (ABE) fermentation of xylose (ModelXYL) was proposed by substituting Embden-Meyerhof-Parnas (EMP) pathway equations in the glucose model (ModelGLC) by pentose phosphate (PP) pathway equations of xylose utilization. We estimated the equation parameters of the PP pathway and set other equation parameters to the same as those in ModelGLC, by which ModelXYL exhibited an r2 value of 0.901 between the experimental time course of metabolites with initial xylose concentrations ranging from 40.7 to 292 mM and the calculated values. The results with the developed model suggested that Clostridium saccharoperbutylacetonicum N1-4 has a robust metabolic network in acid- and solvent-producing pathways. Furthermore, sensitivity analysis revealed that slow substrate utilization would be effective for higher butanol production; this coincided with the experimental results. Therefore, we consider the proposed model to be one of the best kinetic simulation candidates describing the dynamic metabolite behavior in ABE production..
82. Genta Kobayashi, Yoshimi Nakagawa, Yukihiro Tashiro, Kohzo Kanda, Fumio Kato, A novel type II restriction endonuclease from novel Leuconostoc mesenteroides in Ariake sea, Japanese Journal of Lactic Acid Bacteria, 19, 96-99, 2008.06.
83. Isolation of xylose-utilizing lactic acid bacteria from Ariake Sea.
84. Hirotaka Oishi, Yoshihiko Kagawa, Shinji Mitsumizo, Yukihiro Tashiro, Genta Kobayashi, Kazuma Udo, Shigehisa Aoki, Megumi Takayanagi, Zenzo Nagasawa, Kazukuni Araki, Noriko Ohza, Yuichiro Eguchi, Mikio Nakashima, A fatal case of necrotizing fasciitis due to bacterial translocation of Klebsiella oxytoca, Journal of Infection and Chemotherapy, 10.1007/s10156-007-0571-2, 14, 1, 62-65, 2008.01, We report a 73-year-old man with hepatocellular cell carcinoma who had eruptions on and severe pain in the lower leg. Within several hours, the patient's skin lesions had progressed markedly. Magnetic resonance imaging findings were consistent with necrotizing fasciitis. Klebsiella oxytoca was isolated from cultures of biopsy samples taken from the leg. The resulting DNA fingerprint pattern revealed that the enteric bacterium was the same as that obtained from the biopsy samples taken from the leg. Furthermore, a dendrogram showed that genetic proximity between samples was extremely high. These results confirmed that translocation of Klebsiella oxytoca as an enteric pathogen caused the necrotizing fasciitis in this patient..
85. Yukihiro Tashiro, Hideaki Shinto, Miki Hayashi, Shun ichi Baba, Genta Kobayashi, Kenji Sonomoto, Novel high-efficient butanol production from butyrate by non-growing Clostridium saccharoperbutylacetonicum N1-4 (ATCC 13564) with methyl viologen, Journal of Bioscience and Bioengineering, 10.1263/jbb.104.238, 104, 3, 238-240, 2007.09, Non-growing Clostridium saccharoperbutylacetonicum N1-4 hardly produced butanol from only butyrate. As adding glucose to the medium, butyrate utilization and butanol production were stimulated. Addition of 0.1 mM methyl viologen as electron carrier resulted in the highest yield of butanol of 0.671 mol/mol to butyrate and glucose..
86. Hideaki Shinto, Yukihiro Tashiro, Mayu Yamashita, Genta Kobayashi, Tatsuya Sekiguchi, Taizo Hanai, Yuki Kuriya, Masahiro Okamoto, Kenji Sonomoto, Kinetic modeling and sensitivity analysis of acetone-butanol-ethanol production, Journal of Biotechnology, 10.1016/j.jbiotec.2007.05.005, 131, 1, 45-56, 2007.08, A kinetic simulation model of metabolic pathways that describes the dynamic behaviors of metabolites in acetone-butanol-ethanol (ABE) production by Clostridium saccharoperbutylacetonicum N1-4 was proposed using a novel simulator WinBEST-KIT. This model was validated by comparing with experimental time-course data of metabolites in batch cultures over a wide range of initial glucose concentrations (36.1-295 mM). By introducing substrate inhibition, product inhibition of butanol, activation of butyrate and considering the cessation of metabolic reactions in the case of insufficiency of energy after glucose exhaustion, the revised model showed 0.901 of squared correlation coefficient (r2) between experimental time-course of metabolites and calculated ones. Thus, the final revised model is assumed to be one of the best candidates for kinetic simulation describing dynamic behavior of metabolites in ABE production. Sensitivity analysis revealed that 5% increase in reaction of reverse pathway of butyrate production (R17) and 5% decrease in reaction of CoA transferase for butyrate (R15) highly contribute to high production of butanol. These system analyses should be effective in the elucidation which pathway is metabolic bottleneck for high production of butanol..
87. Yukihiro Tashiro, Katsuhisa Takeda, Genta Kobayashi, Kenji Sonomoto, High production of acetone-butanol-ethanol with high cell density culture by cell-recycling and bleeding, Journal of Biotechnology, 10.1016/j.jbiotec.2005.05.031, 120, 2, 197-206, 2005.11, A continuous acetone-butanol-ethanol (ABE) production system with high cell density obtained by cell-recycling of Clostridium saccharoperbutylacetonicum N1-4 has been studied. In conventional continuous culture of ABE without cell-recycling, the cell concentration was below 5.2 g l-1 and the maximum ABE productivity was only 1.85 g l-1 h-1 at a dilution rate of 0.20 h-1. To obtain a high cell density at a faster rate, we concentrated the solventogenic cells of the broth 10 times by membrane filtration and were able to obtain approximately 20 g l-1 of active cells after only 12 h of cultivation. Continuous culture with cell-recycling was then started, and the cell concentration increased gradually through cultivation to a value greater than 100 g l-1. The maximum ABE productivity of 11.0 g l-1 h-1 was obtained at a dilution rate of 0.85 h-1. However, a cell concentration greater than 100 g l-1 resulted in heavy bubbling and broth outflow, which made it impossible to carry out continuous culture. Therefore, to maintain a stable cell concentration, cell-bleeding was performed together with cell-recycling. At dilution rates of 0.11 h-1 and above for cell-bleeding, continuous culture with cell-recycling could be operated for more than 200 h without strain degeneration and the overall volumetric ABE productivity of 7.55 g l -1 h-1 was achieved at an ABE concentration of 8.58 g l-1..
88. Takeshi Zendo, N. Eungruttanagorn, S. Fujioka, Yukihiro Tashiro, K. Nomura, Y. Sera, G. Kobayashi, Jiro Nakayama, A. Ishizaki, Kenji Sonomoto, Identification and production of a bacteriocin from Enterococcus mundtii QU 2 isolated from soybean, Journal of Applied Microbiology, 10.1111/j.1365-2672.2005.02704.x, 99, 5, 1181-1190, 2005.11, Aims: Identification of the bacteriocin produced by Enterococcus mundtii QU 2 newly isolated from soybean and fermentative production of the bacteriocin. Methods and Results: The bacteriocin produced by Ent. mundtii QU 2 inhibited the growth of various indicator strains, including Enterococcus, Lactobacillus, Leuconostoc, Pediococcus and Listeria. The bacteriocin activity was stable at wide pH range and against heat treatment, but completely abolished by proteolytic enzymes. The bacteriocin was purified from the culture supernatant by the three-step chromatographic procedure. Mass spectrometry, amino acid sequencing and DNA sequencing revealed that the bacteriocin was similar to class IIa bacteriocins produced by other Ent. mundtii strains. The bacteriocin production decreased in the absence of glucose, nitrogen sources, or Tween 80 in MRS medium. Additionally, it was strongly suppressed by addition of Ca 2+ (CaCO3 or CaCl2). In pH-controlled fermentations, the highest bacteriocin production was achieved at pH 6.0 whereas the highest cell growth was obtained at pH 7.0. Conclusions: Ent. mundtii QU 2 produced a class IIa bacteriocin. Some growth factors (e.g. Ca2+ and pH) influenced the bacteriocin production. Significance and Impact of the Study: A new soybean isolate, Ent. mundtii QU 2 was found to be a class IIa bacteriocin producer. Factors influencing the bacteriocin production described herein are valuable for applications of the bacteriocins from Ent. mundtii strains..
89. Genta Kobayashi, Koji Eto, Yukihiro Tashiro, Kenichi Okubo, Kenji Sonomoto, Ayaaki Ishizaki, Utilization of excess sludge by acetone-butanol-ethanol fermentation employing Clostridium saccharoperbutylacetonicum N1-4 (ATCC 13564), Journal of Bioscience and Bioengineering, 10.1263/jbb.99.517, 99, 5, 517-519, 2005.05, Clostridium saccharoperbutylacetonicum N1-4 could not grow or produce butanol in excess sludge medium. However, adding glucose to the excess sludge medium resulted in a specific growth rate and butanol productivity of 0.29 h-1 and 0.55 g/l/h, respectively, and the final butanol production reached 9.3 g/l. Since the content of suspended solids in medium reduced to less than 50% of the initial content during acetone-butanol-ethanol (ABE) fermentation, the sludge was quantitatively decreased by this fermentation employing this strain..
90. Yukihiro Tashiro, Katsuhisa Takeda, Genta Kobayashi, Kenji Sonomoto, Ayaaki Ishizaki, Sadazo Yoshino, High butanol production by Clostridium saccharoperbutylacetonicum N1-4 in fed-batch culture with pH-stat continuous butyric acid and glucose feeding method, Journal of Bioscience and Bioengineering, 10.1263/jbb.98.263, 98, 4, 263-268, 2004.10, A pH-stat fed-batch culture by feeding butyric acid and glucose has been studied in an acetone-butanol-ethanol (ABE) fermentation using Clostridium saccharoperbutylacetonicum N1-4. The specific butanol production rate increased from 0.10 g-butanol/g-cells/h with no feeding of butyric acid to 0.42 g-butanol/g-cells/h with 5.0 g/l butyric acid. The pH value in broth decreases with butyric acid production during acidogenesis, and them batyric acid reutilization and butanol prodnction result in a pH increase during solventogensis. The pH-stat fed-batch culture was performed to maintain a constant pH and butyric acid concentration in the culture broth, but feeding only butyric acid could not support butyric acid utilization and butanol production. Subsequently, when a mixture of butyric acid and glucose was fed, butyric acid was utilized and butanol was produced. To investigate the effect of the feeding ratio of butyric acid to glucose (B/G ratio), several B/G ratio solutions were fed. The maximum butanol production was 16 g/7 and the residual glucose concentration in broth was very low at a B/G ratio of 1.4. Moreover, yields of butanol in relation to cell mass and glucose utilization were 54% and 72% higher in pH-stat fed-batch culture with butyric acid than that of conventional batch culture, respectively..


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