Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Food Science  

Theaflavin 3,3'-digallate (TF3), a major polyphenolic component of black tea, exhibits antibacterial effects against many foodborne pathogens. However, the antibacterial mechanisms of TF3 against Listeria monocytogenes remain unclear. In this study, we investigated the effects of TF3 on viability, biofilm, and membrane function of L. monocytogenes by the conventional plating method, crystal violet staining, and microscopy using fluorescent dyes JC-1 and Laurdan, respectively. It was found that TF3 showed excellent antibacterial activity against L. monocytogenes with the minimum inhibitory concentration of 62.5 mg/L. The viable count determined on TSA decreased by 3 log after the treatment for 2 h with TF3 at 62.5 mg/L. The viable count determined on TSA containing 4% NaCl decreased by more than 4 log after the treatment for 30 min with TF3 at the same concentration, suggesting that TF3 gave damage on the cells, enhancing the antibacterial action of 4% NaCl, but the damage was recoverable in the absence of 4% NaCl. To explore the antibacterial mechanisms of TF3, the effects of TF3 on membrane potential and membrane fluidity were investigated. TF3 reduced both membrane potential and fluidity of L. monocytogenes at 62.5 mg/L, suggesting that TF3 damaged the structural integrity of the cell membrane. TF3 reduced biofilm mass of mature biofilm of L. monocytogenes. Moreover, THEAFLAVIN TF40, a commercially available Camellia sinensis leaf extract containing TF3, reduced viable count of L. monocytogenes by 2 log on apple skin. These results suggest the potential of theaflavins as a natural anti-Listeria disinfectant.

DOI： 10.1111/1750-3841.17321

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Food Research International  

This study focused on the isolation and characterization of bacteriophages with specific activity against toxin-producing and multidrug-resistant strains of Bacillus cereus sensu stricto (B. cereus s. s.). Ten different samples yielded six bacteriophages by utilizing the double-layer agar technique. The most promising phage, vB_BceS-M2, was selected based on its broad host range and robust lytic activity against various B. cereus s. s. strains. The phage vB_BceS-M2 had a circular double-stranded DNA genome of 56,482 bp. This phage exhibited stability over a wide range of temperatures and pH values, which is crucial for its potential application in food matrices. The combined effect of phage vB_BceS-M2 and nisin, a widely used antimicrobial peptide, was investigated to enhance antimicrobial efficacy against B. cereus in food. The results suggested that nisin showed synergy and combined effect with the phage, potentially overcoming the growth of phage-resistant bacteria in the broth. Furthermore, practical applications were conducted in various liquid and solid food matrices, including whole and skimmed milk, boiled rice, cheese, and frozen meatballs, both at 4 and 25 °C. Phage vB_BceS-M2, either alone or in combination with nisin, reduced the growth rate of B. cereus in foods other than whole milk. The combination of bacteriophage and nisin showed promise for the development of effective antimicrobial interventions to counteract toxigenic and antibiotic-resistant B. cereus in food.

DOI： 10.1016/j.foodres.2024.114685

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Endolysin, a bacteriophage-derived lytic enzyme, has emerged as a promising alternative antimicrobial agent against rising multidrug-resistant bacterial infections. Two novel endolysins LysPEF1-1 and LysPEF1-2 derived from Enterococcus phage PEF1 were cloned and overexpressed in Escherichia coli to test their antimicrobial efficacy against multidrug-resistant E. faecalis strains and their biofilms. LysPEF1-1 comprises an enzymatically active domain and a cell-wall-binding domain originating from the NLPC-P60 and SH3 superfamilies, while LysPEF1-2 contains a putative peptidoglycan recognition domain that belongs to the PGRP superfamily. LysPEF1-1 was active against 89.86% (62/69) of Enterococcus spp. tested, displaying a wider antibacterial spectrum than phage PEF1. Moreover, two endolysins demonstrated lytic activity against additional gram-positive and gram-negative species pretreated with chloroform. LysPEF1-1 showed higher activity against multidrug-resistant E. faecalis strain E5 than LysPEF1-2. The combination of two endolysins effectively reduced planktonic cells of E5 in broth and was more efficient at inhibiting biofilm formation and removing biofilm cells of E. faecalis JCM 7783T than used individually. Especially at 4 °C, they reduced viable biofilm cells by 4.5 log after 2 h of treatment on glass slide surfaces. The results suggest that two novel endolysins could be alternative antimicrobial agents for controlling E. faecalis infections.

DOI： 10.3390/antibiotics13090884

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Journal of Food Microbiology  

Nowadays, the discovery of alternative natural antimicrobial substances such as bacteriophages, essential oils, and other physical and chemical agents is developing in the food industry. In this study, nine bacteriophages were isolated from various parts of raw chickens and exhibited lytic activities against L. monocytogenes and various Listeria spp. The characterization of phage vB_LmoS-PLM9 was stable at 4 to 50 °C and pH range from 4 to 10. Phage vB_LmoS-PLM9 had a circular, double-stranded genomic DNA with 38,345 bp having endolysin but no antibiotic resistance or virulence genes. Among the eight essential oils tested at 10 %, cinnamon bark, and cassia oils showed the strongest antilisterial activities. The combined use of phage vB_LmoS-PLM9 and cinnamon oils indicated higher efficiency than single treatments. The combination of phage (MOI of 10) and both cinnamon oils (0.03 %) reduced the viable counts of L. monocytogenes and inhibited the regrowth of resistant cell populations in broth at 30 °C. Furthermore, treatment with the combination of phage (MOI of 100) and cinnamon oil (0.125 %) was effective in milk, especially at 4 °C by reducing the viable count to less than lower limit of detection. These results suggest combining phage and cinnamon oil is a potential approach for controlling L. monocytogenes in milk.

DOI： 10.1016/j.ijfoodmicro.2024.110797

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Publisher：European Food Research and Technology  

Bacillus cereus is a spore-forming foodborne pathogen that causes emetic and diarrheal food poisoning. An emetic strain of B. cereus produces spores and an emetic toxin called cereulide, which exhibits high heat resistance. In this study, we investigated the effects of epigallocatechin gallate (EGCg), theaflavin-3’-gallate (TF2b), and theaflavin-3,3’-gallate (TF3), polyphenolic components of tea extracts, on the survivability, spores, and toxin of B. cereus. Among them, EGCg at 62.5 μg/mL and 250 μg/mL showed bacteriostatic and bactericidal effects on B. cereus by damaging the cellular membrane, causing leakage of cellular nucleic acid related substances, and thus inhibiting the growth of B. cereus. However, no significant effects were shown on spore germination by EGCg, TF2b, or TF3 at a concentration of 250 μg/mL in this investigation. Their inhibitory effects were primarily confined to the outgrowth of daughter cells after spore germination. Furthermore, quantitative polymerase chain reaction (qPCR) showed that they suppressed the activity of cesA, a gene associated with cereulide production. At concentrations of 125 µg/mL for TF2b and 62.5 µg/mL for TF3, a discernible attenuation of cytotoxic effects induced by cereulide on HEp-2 cells was evident.

DOI： 10.1007/s00217-024-04593-x

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Journal of Food Microbiology  

The continuous detection of multi-drug-resistant enterococci in food source environments has aroused widespread concern. In this study, 198 samples from chicken products, animal feces, raw milk, and vegetables were collected in Japan and Egypt to investigate the prevalence of enterococci and virulence characterization. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was employed for species identification and taxonomic analysis of the isolates. The results showed that the rates of most virulence genes (efaA, gelE, asa1, ace, and hyl) in the Japanese isolates were slightly higher than those in the Egyptian isolates. The rate of efaA was the highest (94.9 %) among seven virulence genes detected, but the cylA gene was not detected in all isolates, which was in accordance with γ-type hemolysis phenotype. In Enterococcus faecalis, the rate of kanamycin-resistant strains was the highest (84.75 %) among the antibiotics tested. Moreover, 78 % of E. faecalis strains exhibited multi-drug resistance. Four moderately vancomycin-resistant strains were found in Egyptian isolates, but none were found in Japanese isolates. MALDI-TOF MS analysis correctly identified 98.5 % (68/69) of the Enterococcus isolates. In the principal component analysis dendrogram, strains isolated from the same region with the same virulence characteristics and similar biofilm-forming abilities were characterized by clustered distribution in different clusters. This finding highlights the potential of MALDI-TOF MS for classifying E. faecalis strains from food sources.

DOI： 10.1016/j.ijfoodmicro.2024.110768

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Antibiotics  

Bacillus cereus sensu stricto is a foodborne pathogen that causes food poisoning. Their spore and biofilm-forming abilities persist in various environments and foods. This study investigated the prevalence, virulence, antibiotic resistance, and genetic diversity of B. cereus s. s. strains isolated from various food samples. Of 179 samples, 22.34% were positive for B. cereus s. s., with significantly high detection rates in milk products and raw chicken meat. Forty strains were isolated from positive samples. Matrix-assisted laser desorption ionization/time of flight mass spectrometry analysis revealed nine distinct clusters and multi-locus sequence typing revealed 34 sequence types including 23 novel sequences, demonstrating high genetic diversity among the isolates. PCR analysis revealed that all the strains contained at least one toxin gene, but none contained the cytK gene. Antibiotic resistance tests revealed that all isolates were classified as multidrug-resistant, with high resistance levels, particularly to β-lactam antibiotics and vancomycin, but were susceptible to gentamicin. All isolates showed variations in biofilm formation. This study highlights the significant public health risk due to B. cereus s. s. and underscores the need for stringent monitoring and control measures in food production to manage antimicrobial resistance and ensure food safety.

DOI： 10.3390/antibiotics13080774

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https://www.sciencedirect.com/science/article/pii/S0956713523005571

DOI： https://doi.org/10.1016/j.foodcont.2023.110157

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Repository Public URL： 100044

Publisher：Food Control  

Phage-encoded peptidoglycanases (phage endolysins) are hydrolyzing enzymes that break peptidoglycan bonds within infected bacterial cell walls at the end of the lytic cycle. They are promising antibacterial agents capable of controlling major foodborne pathogens. Here, we cloned, overexpressed, and purified the phage-encoded protein LysCPQ7, a putative endolysin from the Clostridium perfringens phage CPQ7. The predicted amino acid sequence indicated that LysCPQ7 exhibited amidase activity to digest the peptidoglycan bond between muramic acid and peptide in bacterial cell walls. LysCPQ7 was characterized as an alkalophilic and thermostable endolysin. It exhibited the highest lytic activity against C. perfringens cells at pH values ranging from 9.0 to 11.0, and was stable at temperatures from −20 to 60 °C. The lytic activity of LysCPQ7 was not significantly (p < 0.05) influenced in the absence/presence of 100, 200, and 300 mM of NaCl. The antibacterial test confirmed that LysCPQ7 reduced the viability of C. perfringens cells by 4.1 log after 6 h of incubation in broth. LysCPQ7 significantly (p < 0.05) decreased the viability of C. perfringens in artificially-contaminated milk and sliced cheese under refrigeration and room temperatures. Our results showed that LysCPQ7 has great potential as a newly emerging biocontrol agent against C. perfringens in dairy and fermented food products.

DOI： 10.1016/j.foodcont.2023.110157

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Microbiology  

Pseudomonas spp., such as P. fluorescens group, P. fragi, and P. putida, are the major psychrophilic spoilage bacteria in the food industry. Bacteriophages (phages) are a promising tool for controlling food-spoilage and food-poisoning bacteria; however, there are few reports on phages effective on food-spoilage bacteria such as Pseudomonas spp. In this study, 12 Pseudomonas phages were isolated from chicken and soil samples. Based on the host range and lytic activity at 30 °C and 4 °C and various combinations of phages, phages vB_PflP-PCS4 and vB_PflP-PCW2 were selected to prepare phage cocktails to control Pseudomonas spp. The phage cocktail consisting of vB_PflP-PCS4 and vB_PflP-PCW2 showed the strongest lytic activity and retarded regrowth of P. fluorescens and P. putida at 30 °C, 8 °C, and 4 °C at a multiplicity of infection of 100. Nucleotide sequence analysis of the genomic DNA indicated that vB_PflP-PCS4 and vB_PflP-PCW2 phages were lytic phages of the Podoviridae family and lacked tRNA, toxin, or virulence genes. A novel endolysin gene was found in the genomic DNA of phage vB_PflP-PCS4. The results of this study suggest that the phage cocktail consisting of vB_PflP-PCS4 and vB_PflP-PCW2 is a promising tool for the biocontrol of psychrophilic food-spoilage pseudomonads during cold storage and distribution.

DOI： 10.1007/s10123-023-00479-2

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Applied Microbiology  

AIMS: The study was to identify the genes involved in phage resistance and to develop an effective biocontrol method to improve the lytic activity of phages against foodborne pathogens. METHODS AND RESULTS: A total of 3,909 single gene-deletion mutants of Escherichia coli BW25113 from the Keio collection were individually screened for genes involved in phage resistance. Phage S127BCL3 isolated from chicken liver, infecting both E. coli BW25113 and O157: H7, was characterized and used for screening. The 10 gene-deletion mutants showed increased susceptibility to phage S127BCL3. Among them, priA gene-deletion mutant strain showed significant susceptibility to the phages S127BCL3 and T7. Furthermore, we investigated the substances that have been reported to inhibit the function of primosomal protein A (PriA) and were used to confirm increased phage susceptibility in E. coli BW25113 (Parent strain) and O157: H7. CONCLUSION: PriA inhibitors at a low concentration showed combined effects with phage against E. coli O157: H7 and delayed the regrowth rate of phage-resistant cells.

DOI： 10.1093/jambio/lxad318

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Language：English   Publisher：Faculty of Agriculture, Kyushu University  

Lettuce (Lactuca sativa) is one of important vegetables taken as raw state. It is expected to be kept as high quality under low temperature conditions, especially freezing state. However, there are few research regarding to its molecular response to abiotic stress of lettuce. As we reported previously, lettuce plants acquire low levels of freeze tolerance. In the present paper, we have isolated 192 cDNA clones corresponding to cold induced genes of lettuce plant by using a PCR–based suppression subtractive hybridization method. Most clones were categorized into 62 distinct known genes based on homology search. Out of the corresponding genes, 45 genes were confirmed to be low–temperature–inducible with reverse transcriptionqPCR. Some of the genes encoded stress–related proteins, such as late embryogenesis abundant proteins including dehydrin, which were expected to be involved in enhancement of freezing tolerance. On the other hand, some of proteins encoded by genes were suspected to be involved in suppressing the enhancement of freezing tolerance, such as vacuolar processing enzyme (VPE), adagio protein, and gigantea–like protein. In particular, VPE have been reported to be associated with program cell death, suggesting that it is negatively involved in freezing tolerance of lettuce.

DOI： 10.5109/7169359

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Language：English   Publisher：Japanese Society for Food Science and Technology  

<p>In this study, the <i>dnaK</i> gene-deletion mutant strain of <i>Escherichia coli</i> BW25113 showed a higher susceptibility than the wild-type strain of <i>E. coli</i> BW25113 to phage S127BCL3. Flavonoids, myricetin and quercetin which had been reported to suppress the role of DnaK were tested to examine their effects on the phage susceptibility of <i>E. coli</i> BW25113. A 6-h pretreatment with 500 µmol/L myricetin or quercetin increased the phage susceptibility of <i>E. coli</i> BW25113. A similar result was observed in <i>E. coli</i> O157:H7. Real-time quantitative polymerase chain reaction (qPCR) was conducted to investigate the effects of flavonoids on the transcription of chaperone genes (<i>dnaK, dnaJ, groEL</i>, and <i>grpE</i>) in <i>E. coli.</i> Pretreatment of wild-type <i>E. coli</i> BW25113 with flavonoids decreased the transcription of chaperone genes. This is the first report demonstrating the enhancement of the phage susceptibility of both <i>E. coli</i> BW25113 and <i>E. coli</i> O157:H7 by flavonoids. The results of this study on the combined effects of flavonoids involved in foods and phages on <i>E. coli</i> provide scientific bases for development of a novel biocontrol method of foodborne bacteria.</p>

DOI： 10.3136/fstr.fstr-d-23-00186

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DOI： 10.1128/MRA.00504-23

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Language：English   Publisher：Springer  

Contaminated food with antibiotic-resistant Enterococcus spp. could be the vehicle for transmitting Enterococcus to humans and accordingly cause a public health problem. The accumulation of biogenic amines produced by Enterococcus faecalis (E. faecalis) in food may have cytological effects. Bacteriophages (phage in short) are natural antimicrobial agents and can be used alone or in combination with other food preservatives to reduce food microbial contaminants. The aim of this study was to isolate a novel phage against E. faecalis and determine its host range to evaluate its potential application. Bacteriophage, vB_EfKS5, with a broad host range, was isolated to control the growth of E. faecalis. The vB_EfKS5 genome is 59,246 bp in length and has a GC content of 39.7%. The computational analysis of phage vB_EfKS5 genome confirmed that it does not contain any lysogenic, toxic, or virulent genes. Phage vB_EfKS5 exhibited lytic activity against most E. faecalis isolates with different multiplicities of infections and it infected 75.5% (22/29) of E. faecalis isolates and 42.3% (3/7) of E. faecium isolates. It was also able to destroy the biofilm formed by E. faecalis with different MOIs. Phage vB_EfKS5 alone or in combination with nisin could control the growth of E. faecalis in broth and milk. Based on its high productivity, stability, short latent period, and large burst size, phage vB_EfKS5 has a high potential for applications both in food and medical applications.

CiNii Research

Language：English   Publisher：AMB Express  

Contaminated food with antibiotic-resistant Enterococcus spp. could be the vehicle for transmitting Enterococcus to humans and accordingly cause a public health problem. The accumulation of biogenic amines produced by Enterococcus faecalis (E. faecalis) in food may have cytological effects. Bacteriophages (phage in short) are natural antimicrobial agents and can be used alone or in combination with other food preservatives to reduce food microbial contaminants. The aim of this study was to isolate a novel phage against E. faecalis and determine its host range to evaluate its potential application. Bacteriophage, vB_EfKS5, with a broad host range, was isolated to control the growth of E. faecalis. The vB_EfKS5 genome is 59,246 bp in length and has a GC content of 39.7%. The computational analysis of phage vB_EfKS5 genome confirmed that it does not contain any lysogenic, toxic, or virulent genes. Phage vB_EfKS5 exhibited lytic activity against most E. faecalis isolates with different multiplicities of infections and it infected 75.5% (22/29) of E. faecalis isolates and 42.3% (3/7) of E. faecium isolates. It was also able to destroy the biofilm formed by E. faecalis with different MOIs. Phage vB_EfKS5 alone or in combination with nisin could control the growth of E. faecalis in broth and milk. Based on its high productivity, stability, short latent period, and large burst size, phage vB_EfKS5 has a high potential for applications both in food and medical applications.

DOI： 10.1186/s13568-023-01628-6

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Applied Microbiology  

AIMS: Isolation and characterization of Enterococcus phages and application of phage cocktail to control E. faecalis in milk. METHODS AND RESULTS: For phage isolations, double layer agar method was used. Host range of the phages were determined by the spot test. Twelve phages with varying host ranges were isolated. Phages PEF1, PEF7b, and PEF9 with different host ranges and lytic activities were selected for phage cocktails. Compared to two-phages cocktails tested, the cocktail containing all the three phages displayed stronger antibacterial and biofilm removal activities. The cocktail treatment reduced viable E. faecalis in biofilm by 6 log within 6 h at both 30°C and 4°C. In milk, the cocktail gradually reduced the viable count of E. faecalis and the count reached below the lower limit of detection at 48 h at 4°C. CONCLUSION: The strong bactericidal and biofilm removal activities of the phage cocktail suggest the potential of this cocktail as a natural biocontrol agent for combating E. faecalis in milk.

DOI： 10.1093/jambio/lxad250

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Journal of Food Microbiology  

Salmonella spp., one of the most frequently reported bacteria, causes foodborne illness and economic losses. Due to the threat of increasing antibiotic resistant foodborne pathogens, application of bacteriophages as novel antibacterial agents in food matrices has become an emerging strategy. In this study, a novel Salmonella phage PS3-1 with high lytic activity against Salmonella Typhimurium was identified from previously isolated phages. PS3-1 belonged to the class Caudoviricetes with a broad host range, and had relatively short latent period (15 min), large burst size (92 PFU/cell), high pH stability (pH 3.0-11.0) and thermal tolerance (4-60 °C). Genome sequencing analysis showed that PS3-1 genome consisted of 107,110 bp DNA, without antibiotic resistance and virulence related genes. The results of growth curve and time-kill assay showed that PS3-1 not only inhibited the growth of S. Typhimurium, but also effectively decreased the viable cell counts (0.30-4.72 log) after 24-h incubation at 7, 25 and 37 °C (P < 0.05). Moreover, >1.28 log of established biofilm cells were effectively removed after 24-h treatment with PS3-1. Besides, PS3-1 significantly reduced the viability of S. Typhimurium in milk, lettuce, raw pork meat and ready-to-eat steamed-chicken breast at different temperatures (P < 0.05). These results demonstrated that PS3-1 may be an excellent antibacterial agent for controlling S. Typhimurium in food industry.

DOI： 10.1016/j.ijfoodmicro.2023.110295

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https://www.sciencedirect.com/science/article/pii/S0882401023003662

DOI： https://doi.org/10.1016/j.micpath.2023.106333.

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Repository Public URL： 105537

Language：English   Publishing type：Research paper (scientific journal)  

This study aimed to investigate the occurrence, antibiotic resistance, and biofilm formation of Escherichia coli in the Vietnamese Pangasius fish processing facility. Among 144 samples including Pangasius fish, wash water, food contact surfaces, and personnel gloves, 18 E. coli isolates was detected and characterized. The E. coli was detected most frequently in wash water samples (22%, 8/36), followed by Pangasius fish (18%, 8/45). According to the antibiotic susceptibility test by the disc diffusion method, isolates showed the highest resistance against sulfamethoxazole/trimethoprim (45%), followed by tetracycline (39%), whereas all the E. coli isolates were susceptible to meropenem and fosfomycin. Notably, 39% of the isolates (7/18) were found to be multidrug resistant while no E. coli isolates were confirmed as extended-spectrum β-lactamase producers by the double-disk synergy test. The potency to form biofilm on the polystyrene surface of E. coli isolates indicated that 44% of the isolates (8/18) were classified as weak, 39% (7/18) as moderate, and 17% (3/18) as strong biofilm formers. Interestingly, multidrug resistant E. coli isolates were observed in moderate and strong biofilm producers. Additionally, either slightly acidic hypochlorous water with 40 mg/L of available chlorine or sodium hypochlorite with 100 mg/L of available chlorine exhibited a significant reduction in biofilm mass and biofilm cells of E. coli isolates. This study may provide helpful information about the actual state of E. coli isolates for effective control in the fish processing plant.

DOI： https://doi.org/10.1016/j.heliyon.2023.e20727.

Other Link： 公開

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Microbial Pathogenesis  

This study investigated the prevalence, serotype, antimicrobial resistance (AMR), virulence potential, and biofilm formation of Listeria monocytogenes isolated in 2022 in Japan and compared their profiles with those of isolates in 2012 and 2017. A total of 85 chicken samples were randomly collected from different supermarkets in Fukuoka in 2022. L. monocytogenes were isolated by conventional method and characterized by MALDI-TOF MS. Among 85 samples tested in 2022, 9 (10.6%) were positive for L. monocytogenes and 17 strains were isolated from the positive samples. The isolates were serotyped as 1/2b (41.2%), 3a (29.4%), 3b (23.5%) and 1/2a (5.9%). Antimicrobial susceptibility tests of the 2022 isolates showed susceptibility to majority of the antibiotics, except cefoxitin, oxacillin, and fosfomycin. Compared to the previous surveillance results, the prevalence of L. monocytogenes in 2022 (10.6%) was significantly lower (p < 0.05) than those of the isolates in 2017 (24%) and 2012 (52.9%). The distribution of serotypes 1/2a and 1/2b decreased over time, and serotype 4b was not detected in the 2022 isolates. The proportion of multidrug resistant strains in 2022 (16.7%) was significantly lower than those in 2012 (46.7%) and 2017 (82.6%). Moreover, a total of 36 isolates (12 isolates/ year) were used to detect the virulence genes (hlyA, plcA, clpC, and inlA) and biofilm-forming capacity. Most of the isolates from different years harboured four virulence genes. The biofilm formation of the 2022 isolates was significantly weaker (p < 0.05) than those of the 2012 and 2017 isolates. Thus, despite the low rates of contamination in chicken meat and AMR of the isolates, virulent L. monocytogenes contamination in food should still be acknowledged.

DOI： 10.1016/j.micpath.2023.106333

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Heliyon  

This study aimed to investigate the occurrence, antibiotic resistance, and biofilm formation of Escherichia coli in the Vietnamese Pangasius fish processing facility. Among 144 samples including Pangasius fish, wash water, food contact surfaces, and personnel gloves, 18 E. coli isolates was detected and characterized. The E. coli was detected most frequently in wash water samples (22%, 8/36), followed by Pangasius fish (18%, 8/45). According to the antibiotic susceptibility test by the disc diffusion method, isolates showed the highest resistance against sulfamethoxazole/trimethoprim (45%), followed by tetracycline (39%), whereas all the E. coli isolates were susceptible to meropenem and fosfomycin. Notably, 39% of the isolates (7/18) were found to be multidrug resistant while no E. coli isolates were confirmed as extended-spectrum β-lactamase producers by the double-disk synergy test. The potency to form biofilm on the polystyrene surface of E. coli isolates indicated that 44% of the isolates (8/18) were classified as weak, 39% (7/18) as moderate, and 17% (3/18) as strong biofilm formers. Interestingly, multidrug resistant E. coli isolates were observed in moderate and strong biofilm producers. Additionally, either slightly acidic hypochlorous water with 40 mg/L of available chlorine or sodium hypochlorite with 100 mg/L of available chlorine exhibited a significant reduction in biofilm mass and biofilm cells of E. coli isolates. This study may provide helpful information about the actual state of E. coli isolates for effective control in the fish processing plant.

DOI： 10.1016/j.heliyon.2023.e20727

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Language：Japanese   Publisher：Japanese Society for Food Science and Technology  

<p>Bacterial persister cells are metabolically dormant cells in which cell activities such as protein synthesis and cell division are somehow drastically slowed down, so that they can survive under intensive antibiotic treatment that targets such cell activities. This review summarizes information about persister cells such as their history, definition, mechanism of formation, threats to clinical environments, and how to control them. In addition to such information, this review also introduces our recent studies on the physical stress tolerance of persister cells and their possible control in food environments. We demonstrated that some bacterial persister cells are indeed highly heat and acid tolerant compared to normal cells, although diversity was discovered in persister cell populations. We also found that indole and its derivatives or acetic acid are promising candidates for persister cell eradication in food environments. We believe that this review will aid in wider attention to and understanding of the importance of these quiet yet clever bacterial persister cells.</p>

DOI： 10.3136/nskkk.nskkk-d-23-00035

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Salmonella spp., one of the most frequently reported bacteria, causes foodborne illness and economic losses. Due to the threat of increasing antibiotic resistant foodborne pathogens, application of bacteriophages as novel antibacterial agents in food matrices has become an emerging strategy. In this study, a novel Salmonella phage PS3-1 with high lytic activity against Salmonella Typhimurium was identified from previously isolated phages. PS3-1 belonged to the class Caudoviricetes with a broad host range, and had relatively short latent period (15 min), large burst size (92 PFU/cell), high pH stability (pH 3.0-11.0) and thermal tolerance (4-60 ℃). Genome sequencing analysis showed that PS3-1 genome consisted of 107,110 bp DNA, without antibiotic resistance and virulence related genes. The results of growth curve and time-kill assay showed that PS3-1 not only inhibited the growth of S. Typhimurium, but also effectively decreased the viable cell counts (0.30-4.72 log) after 24-h incubation at 7, 25 and 37 ℃ (P < 0.05). Moreover, more than 1.28 log of established biofilm cells were effectively removed after 24-h treatment with PS3-1. Besides, PS3-1 significantly reduced the viability of S. Typhimurium in milk, lettuce, raw pork meat and ready-to-eat steamed-chicken breast at different temperatures (P < 0.05). These results demonstrated that PS3-1 may be an excellent antibacterial agent for controlling S. Typhimurium in food industry.

DOI： https://doi.org/10.1016/j.ijfoodmicro.2023.110295

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Repository Public URL： 109886

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Antibiotics  

Bacterial food poisoning cases due to Salmonella and E. coli O157:H7 have been linked with the consumption of a variety of food products, threatening public health around the world. This study describes the combined effects of a phage cocktail (STG2, SEG5, and PS5), EDTA, nisin, and polylysine against the bacterial cocktail consisting of S. typhimurium, S. enteritidis, and E. coli O157:H7. Overall, phage cocktail (alone or in combination with nisin or/and polylysine) not only showed great antibacterial effects against bacterial cocktail at different temperatures (4 °C, 24 °C, and 37 °C), but also totally inhibited the emergence of phage resistance during the incubation period. These results suggest that the combination of phages with nisin or/and polylysine has great potential to simultaneously control S. typhimurium, S. enteritidis, and E. coli O157:H7.

DOI： 10.3390/antibiotics12061077

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https://www.mdpi.com/2079-6382/12/6/1077

DOI： https://www.mdpi.com/2079-6382/12/6/1077

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Repository Public URL： 521

Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.1016/j.jfp.2023.100044

Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.1016/j.jfp.2023.100044

Other Link： 公開

Repository Public URL： 104010

Publisher：Journal of Food Protection  

Biofilm formation of Listeria monocytogenes in food processing environments cause potential source of cross-contamination to foodstuffs; hence, the control of biofilm is currently addressed to find effective solutions for preventing biofilm formation or eliminating the established one. Forty‐five strains of Listeria monocytogenes isolated from Pangasius fish‐processing plants were studied for their capability to form a biofilm on 96‐well microtiter plate by using the conventional crystal violet staining. Additionally, the inhibitory effect of biofilm formation by food additives including monascus pigment and ε‐polylysine was examined. The average OD value showing biofilm mass of all 45 strains L. monocytogenes increased with an increasing temperature and time (p < 0.05). Monascus pigment and ε‐polylysine significantly decreased biofilm formation by 80 ± 5.5% and 20 ± 5.9%, respectively, at the tested concentration (p < 0.05) Further, the effects of lysozyme (0.1 mg/mL) alone or in combination with slightly acidic hypochlorous water (SAHW) with 40 mg/L available chlorine or sodium hypochlorite (NaOCl) with 100 mg/L available chlorine against 7‐d established biofilm of L. monocytogenes were investigated. The results indicated that slightly acidic hypochlorous water alone exhibited significant antibacterial activity (p < 0.05), decreasing the viable count by 5.2 ± 0.5 log CFU/mL. It seems that sequential treatment of lysozyme and SAHW showed an additional efficacy against biofilm of L. monocytogenes on polystyrene plate surface, reducing 70% of biomass of biofilm and 7.6 ± 0.3 log of biofilm viable cells (p < 0.05). Additionally, SAHW exhibited greater bactericidal activity against viable biofilm cells than NaOCl did. This result reveals that SAHW is a promising disinfectant agent against L. monocytogenes and the potential alternative to NaOCl in practice.

DOI： 10.1016/j.jfp.2023.100044

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Journal of Food Microbiology  

As one major foodborne pathogen, Salmonella can cause serious food poisoning outbreaks worldwide. Bacteriophage therapy is increasingly considered as one of the promising antibacterial agents for the biocontrol of foodborne pathogens. In the current study, a lytic phage STG2 capable of infecting S. enteritidis and S. typhimurium was characterized, and its efficacy in reducing these foodborne pathogens in both planktonic and biofilm forms was evaluated on cabbage and various surfaces. Genomic characterization revealed that phage STG2 was Siphoviridae phage (Epseptimavirus genus) with a dsDNA genome comprising of 114,275 bp and its genome does not contain any genes associated to antibiotic resistance, toxins, lysogeny, or virulence factors. Additionally, phage STG2 exhibited great efficacy in reducing (>2 Log) planktonic cells on cabbage as well as the biofilms formed on cabbage, polystyrene, and stainless steel, suggesting that phage STG2 is capable of simultaneously controlling both S. enteritidis and S. typhimurium contaminations on food and food-related surfaces.

DOI： 10.1016/j.ijfoodmicro.2022.109999

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DOI： https://doi.org/10.1016/j.ijfoodmicro.2022.109999

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Toxicology in Vitro  

Enterohemorrhagic or Shiga toxin-producing Escherichia coli is a food-poisoning bacterium that grows in the intestine to produce Shiga toxin (Stx). In this study, the effects of 20 polyphenols on the cytotoxicity of Stx1 and Stx2 in Vero cells were investigated. Among these, epigallocatechin gallate, butein, isorhapontigenin, hesperetin, morin, luteolin, resveratrol, and rhapontigenin showed inhibitory effects on the cytotoxicity of Stxs at 0.4 mmol/L. Furthermore, Vero cells pre-treated with these polyphenols were resistant to Stx at 0.4 mmol/L. However, luteolin showed the most potent inhibitory and cytoprotective effect against Stxs at 0.08 mmol/L or more. This inhibitory mechanism of luteolin was determined using a cell-free protein synthesis system and quantitative reverse transcription PCR assay to detect depurination of 28S rRNA in Vero cells. Luteolin did not inhibit the cell-free protein synthesis by Stxs, suggesting that the enzymatic activity of the Stx A subunit was not inhibited by luteolin. The depurination of 28S rRNA by Stxs was also investigated in Vero cells. The 28S rRNA depurination by Stxs was suppressed in Vero cells treated with Stxs which had been pretreated with luteolin. These results suggest that luteolin inhibits the incorporation of Stxs into Vero cells. This is the first report to show that luteolin inhibits the cytotoxicity of both Stx1 and Stx2 by inhibiting the incorporation of Stxs into Vero cells.

DOI： 10.1016/j.tiv.2022.105537

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Other Link： https://www.sciencedirect.com/science/article/pii/S0956713521005983

Repository Public URL： http://hdl.handle.net/2324/4774196

Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Journal of Food Microbiology  

Salmonella enterica subsp. enterica serotype Typhimurium (S. Typhimurium) is one of the most prevalent foodborne pathogens responsible for food poisoning and is spread through the consumption of contaminated poultry products. In this study, four antimicrobial peptides (AMPs) with varying hydrophobicity and helical structure-forming tendencies were designed and synthesized based on the amino acid sequences of peptides from egg white hydrolysate. Two of these AMPs, P1R3 (KSWKKHVVSGFFLR) and P1C (KSWKKHVVSGFFLRLWVHKK), exhibited inhibitory activity against S. Typhimurium and compromised its biofilm-forming ability. Investigation of their modes of action revealed that P1R3 and P1C interact with and permeabilize the cytoplasmic membrane of bacteria, leading to membrane potential dissipation, damage to membrane integrity, and consequent bacterial death. P1R3 also bound to S. Typhimurium DNA, resulting in DNA aggregation or precipitation. Moreover, both peptides showed negligible cytotoxicity to Vero cells, and P1C displayed significant antimicrobial activity in chicken meat. Peptides P1R3 and P1C, therefore, have the potential to be developed as promising food preservatives, especially against pathogenic S. Typhimurium.

DOI： 10.1016/j.ijfoodmicro.2022.109802

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This study illustrates the effectiveness of slightly acidic hypochlorous water (SAHW) in comparison with sodium hypochlorite (NaOCl) in reducing biomass and viable cells in biofilms established by the dual species, Listeria monocytogenes and Escherichia coli, on a microtiter plate and stainless-steel coupon. The SAHW and NaOCl treatments exhibited significant efficacy against biofilms (p < 0.05) on both surfaces. Additionally, compared with NaOCl treatment, SAHW treatment significantly reduced biofilm formation (p < 0.05). With its high antibiofilm activity, SAHW not only reduced the biomass of biofilms, but also significantly decreased viable biofilm cells to 5 log CFU/mL or ≤1 log CFU/cm2 on microtiter plates and stainless-steel surfaces, respectively. These results indicate that SAHW is a potential candidate for disinfectants against biofilms on various food contact surfaces.

DOI： https://doi.org/10.3136/fstr.FSTR-D-22-00074

Language：English   Publishing type：Research paper (scientific journal)  

Clostridium perfringens is a major cause of foodborne disease in developed countries. The aim of this study was to isolate and characterize phages specific to C. perfringens to evaluate the most efficient phage cocktail for the biocontrol of C. perfringens, both in vitro and in curry roux. In this study, four phages were isolated from chicken meat and were morphologically and genetically characterized along with two phages previously isolated in our laboratory that display different host lysis spectra. Phage cocktail CP11, consisting of phages CPQ3, 7, 8, and 10, showed the broadest host range. Electron micrograph images suggested that all four phages belong to the Podoviridae family, and none of them carry any antibiotic resistance or toxin genes. Notably, the phages were stable at various pH values and in curry roux. Cocktails consisting of six, five, and four phages at the same concentrations were examined to determine the most effective phage cocktail. Phage cocktail PC11 significantly decreased the viable count of C. perfringens to a value less than the lower detection limit up to 48 h at both 8 and 37 °C in broth and at 24 °C in the curry roux. These results suggest that phage cocktail PC11 is a promising natural biocontrol agent against C. perfringens in vitro and in curry roux.

DOI： https://doi.org/10.1016/j.ijfoodmicro.2022.109886

Language：English   Publishing type：Research paper (scientific journal)  

Salmonella enterica subsp. enterica serotype Typhimurium (S. Typhimurium) is one of the most prevalent foodborne
pathogens responsible for food poisoning and is spread through the consumption of contaminated poultry
products. In this study, four antimicrobial peptides (AMPs) with varying hydrophobicity and helical structureforming
tendencies were designed and synthesized based on the amino acid sequences of peptides from egg
white hydrolysate. Two of these AMPs, P1R3 (KSWKKHVVSGFFLR) and P1C (KSWKKHVVSGFFLRLWVHKK),
exhibited inhibitory activity against S. Typhimurium and compromised its biofilm-forming ability. Investigation
of their modes of action revealed that P1R3 and P1C interact with and permeabilize the cytoplasmic membrane
of bacteria, leading to membrane potential dissipation, damage to membrane integrity, and consequent bacterial
death. P1R3 also bound to S. Typhimurium DNA, resulting in DNA aggregation or precipitation. Moreover, both
peptides showed negligible cytotoxicity to Vero cells, and P1C displayed significant antimicrobial activity in
chicken meat. Peptides P1R3 and P1C, therefore, have the potential to be developed as promising food preservatives,
especially against pathogenic S. Typhimurium.

DOI： https://doi.org/10.1016/j.ijfoodmicro.2022.109802

Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.1016/j.fm.2022.104010

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Food Microbiology  

Escherichia coli O157:H7 is one of the most important foodborne pathogens that can persist in leafy green vegetables and subsequently produce biofilms. Biofilm formation is an ongoing concern in the food industry as biofilms are relatively resistant to a variety of antimicrobial treatments. In the present study, we evaluated the combined effects of phage FP43 and mild-heated slightly acidic hypochlorous water (SAHW) in reducing established biofilms on lettuce. Prior to the sequential treatments involving phage-SAHW and SAHW-phage for long-term storage, equal inoculum densities of E. coli O157:H7 and E. coli O91:H- were added on iceberg lettuce surfaces and the lettuce samples were stored at 10 °C for 48 h to allow biofilm formation. The sequential treatment with phage FP43 and SAHW significantly decreased the number of adhered cells, especially the combination of phage FP43 at 25 °C for 2 h and mild-heated SAHW, which considerably eliminated E. coli viable biofilm cells to undetectable levels (>3 log CFU/piece). However, the biofilms were not completely removed, as evidenced via SEM observation. Additionally, sequential treatment with SAHW and phage caused continuous reductions in viable counts, decreasing the viability of E. coli O157:H7 and total E. coli to the lower limit of detection after incubation for 5 d. Meanwhile, bacterial regrowth was observed after treatment with SAHW alone. These results indicated that the combination of phage and SAHW could be considered as a promising strategy to control the formation of E. coli O157:H7 biofilms on lettuce.

DOI： 10.1016/j.fm.2022.104010

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Language：Japanese   Publisher：Japan Society for Bioscience, Biotechnology, and Agrochemistry  

<p>細菌感染に苦しめられてきた人類の救世主として抗生物質が発見され，その黄金時代が幕を開けたその瞬間から，細菌たちはその効果を打ち消す術をすでに見つけていた．病原菌たちが耐性遺伝子の獲得，突然変異によって抗生物質を克服し，人類はまた新たな抗生物質を発見，開発して対抗する，というイタチごっこを続けてきたが，新たな抗生物質の発見，開発が追いついておらず，人類は今，劣勢に立たされている．この薬剤耐性菌問題はよく知られていることであるが，遺伝子変異による耐性菌とは似て非なる“もう一つの耐性菌”，“Persister”についてはあまり知られていない．本解説では，このPersisterについて薬剤耐性菌と比較しながら紹介したい．</p>

DOI： 10.1271/kagakutoseibutsu.60.232

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Journal of Food Microbiology  

Clostridium perfringens is one of the most important foodborne pathogens in developed countries. It causes severe food poisoning outbreaks worldwide, along with mortality and economic losses. Recently, bacteriophages have been investigated as an alternative tool to control pathogenic bacteria in the food industry. In this study, 19 Clostridium perfringens and 6 Clostridium perfringens bacteriophages were isolated from chicken meat. According to host range and stability tests, bacteriophage CPQ1 showed high thermostability and the broadest host range. The electron micrograph image of this bacteriophage suggested that it belongs to the Picovirinae subfamily of the Podoviridae family. Nucleotide sequence analysis of the genomic DNA indicated the absence of any antibiotic resistance, toxin, or virulence genes. In broth, CPQ1 showed strong lytic activity with a low MOI of 1, decreasing the OD600 of Clostridium perfringens cell suspension from 0.2 to 0.02 at 37 °C in 2 h. In pasteurized milk and chicken meat, CPQ1 with an MOI of 10 also caused a significant decrease in viable counts of Clostridium perfringens compared to the bacteriophageless control at both 24 °C and 37 °C. This is the first report on the application of bacteriophage to control Clostridium perfringens in foods.

DOI： 10.1016/j.ijfoodmicro.2021.109446

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In this study, the occurrence, serogroups, virulence genes, antibiotic susceptibility profiles, and diversity were estimated for Listeria monocytogenes isolated from Pangasius fish in two processing facilities in Vietnam. L. monocytogenes was most frequently detected in wash water samples at 20.8 % (15 out of 72), and in Pangasius fish it was 16.6 % (15 out of 90 fish samples). Serotypes 1/2b were dominant, and internalin genes (inlA, inlC, and inlJ) were found in all the L. monocytogenes isolates. Most of the isolates were resistant to cefoxitin, oxacillin, and fosfomycin. Genotyping of L. monocytogenes by random amplified polymorphic DNA analysis revealed three clusters of the isolates specific to the facilities to some extent. This study suggests a high risk of L. monocytogenes contamination from wash water to fish. Hence, maintaining the quality of water and designing sanitation procedures to reduce L. monocytogenes contamination are required to ensure food safety at Pangasius fish processing plants.

DOI： DOI: 10.3136/fstr.FSTR-D-21-00195

Publisher：Food Control  

The gene encoding LysSTG2, a novel endolysin from Salmonella-lytic bacteriophage STG2, has been cloned, overexpressed, and characterized previously. In this study, LysSTG2 was used to control Pseudomonas aeruginosa and P. putida, which showed high sensitivity to LysSTG2, in bottled water, milk, chicken breast, salmon, and the biofilms formed on the surface of polystyrene resin and stainless steel. In bottled water, LysSTG2 combined with EDTA reduced the viable counts of P. aeruginosa and P. putida by 2.2 log and to lower than the limit of detection, respectively. However, there was no significant decrease in viable counts in pasteurized milk artificially contaminated with these bacteria. Meanwhile, the addition of 1 mg/mL LysSTG2 alone reduced the viable counts of P. aeruginosa and P. putida by 0.6 log in chicken and 1.1 log in salmon samples contaminated with these bacteria, respectively. Further reduction in viable counts in combination with EDTA was not observed. Additionally, a strong effect of LysSTG2 on the removal of P. aeruginosa and P. putida biofilms was observed on the polystyrene resin and stainless steel surfaces, displaying more than 99.9% decrease in viable biofilm cells after 2 h of treatment at 37 °C. The results of this study suggest that LysSTG2 has the potential to control both planktonic and biofilm cells of Pseudomonas. Further investigations are required to optimize and improve the use of the endolysin for application in food and food processing facilities.

DOI： 10.1016/j.foodcont.2021.108460

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Language：English   Publisher：Japanese Society for Food Science and Technology  

<p>This study illustrates the effectiveness of slightly acidic hypochlorous water (SAHW) in comparison with sodium hypochlorite (NaOCl) in reducing biomass and viable cells in biofilms established by the dual species, <i>Listeria monocytogenes</i> and <i>Escherichia coli</i>, on a microtiter plate and stainless-steel coupon. The SAHW and NaOCl treatments exhibited significant efficacy against biofilms (<i>p</i> < 0.05) on both surfaces. Additionally, compared with NaOCl treatment, SAHW treatment significantly reduced biofilm formation (<i>p</i> < 0.05). With its high antibiofilm activity, SAHW not only reduced the biomass of biofilms, but also significantly decreased viable biofilm cells to 5 log CFU/mL or ≤1 log CFU/cm2 on microtiter plates and stainless-steel surfaces, respectively. These results indicate that SAHW is a potential candidate for disinfectants against biofilms on various food contact surfaces.</p>

DOI： 10.3136/fstr.fstr-d-22-00074

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CiNii Research

Language：English   Publisher：Japanese Society for Food Science and Technology  

<p>In this study, the occurrence, serogroups, virulence genes, antibiotic susceptibility profiles, and diversity were estimated for <i>Listeria monocytogenes</i> isolated from <i>Pangasius</i> fish in two processing facilities in Vietnam. <i>L. monocytogenes</i> was most frequently detected in wash water samples at 20.8% (15 out of 72), and in <i>Pangasius</i> fish it was 16.6% (15 out of 90 fish samples). Serotypes 1/2b were dominant, and internalin genes (<i>inlA, inlC</i>, and <i>inlJ</i>) were found in all the <i>L. monocytogenes</i> isolates. Most of the isolates were resistant to cefoxitin, oxacillin, and fosfomycin. Genotyping of <i>L. monocytogenes</i> by random amplified polymorphic DNA analysis revealed three clusters of the isolates specific to the facilities to some extent. This study suggests a high risk of <i>L. monocytogenes</i> contamination from wash water to fish. Hence, maintaining the quality of water and designing sanitation procedures to reduce <i>L. monocytogenes</i> contamination are required to ensure food safety at <i>Pangasius</i> fish processing plants.</p>

DOI： 10.3136/fstr.fstr-d-21-00195

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CiNii Research

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The prevalence and antimicrobial resistance (AMR) profile were investigated in Campylobacter jejuni and Campylobacter coli in chicken and pork in Fukuoka, Japan in 2019. Their AMR profiles were compared with those of C. jejuni and C. coli strains isolated in 2013. A total of 53 chicken and 14 pork samples were collected from different supermarkets in Fukuoka in 2019. Campylobacter spp. were isolated by conventional method and characterized by PCR and MALDI-TOF MS. Among 53 chicken samples tested in 2019, 24.5% and 5.7% were positive for C. jejuni and C. coli, respectively, and three (21.4%) of 14 pork samples were positive for C. coli, but not C. jejuni. From the positive samples, 13 and six strains of C. jejuni and C. coli were isolated, respectively. Antimicrobial susceptibility test against 12 different antimicrobials were performed on 48 isolates (43 C. jejuni and five C. coli) from chicken in 2013 and 19 isolates (13 C. jejuni from chicken, three C. coli from chicken and three C. coli from pork) in 2019 using the disk diffusion method. All the C. jejuni and C. coli isolated in 2013 and 2019 were highly resistant to cefazolin and sulfamethoxazole/trimethoprim. Among the C. jejuni isolates from chickens, 25.6% of 2013 isolates were resistant to nalidixic acid, ciprofloxacin, and levofloxacin, and 7% to ampicillin and minocycline, while 30.8% of the isolates were resistant to minocycline, 23.1% to nalidixic acid, ciprofloxacin, and levofloxacin, and 15.4% to ampicillin in 2019. Among the C. coli isolates, 80% of isolates from chickens in 2013, and 33.3% from chicken and 100% from pork in 2019 were resistant to nalidixic acid, ciprofloxacin, and levofloxacin. The frequency of multi-drug resistant (MDR) C. jejuni and C. coli strains from chickens in 2019 were 30.8% and 33.3%, respectively, which were lower than those isolated in 2013 (37.2% and 100%, respectively). One C. jejuni and two C. coli isolates from 2013 were resistant to six antibiotics. However, two C. jejuni and one C. coli isolate from chickens in 2019 were resistant to seven and five antibiotics, respectively. All the C. coli isolates from pork in 2019 were resistant to five antibiotics. The high frequency of AMR strains in C. coli isolates from pork suggests that appropriate use of antimicrobials is required in swine husbandry.

DOI： DOI: 10.1016/j.ijfoodmicro.2021.109440

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DOI： 10.1016/j.fm.2021.103791

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.fm.2021.103791

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DOI： 10.1016/j.fm.2021.103853

Language：English   Publishing type：Research paper (bulletin of university, research institution)  

DOI： 10.5109/4363550

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DOI： 10.1016/j.lwt.2020.109945

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DOI： 10.1016/j.jgar.2020.06.006

Language：English   Publishing type：Research paper (scientific journal)  

Salmonella Enteritidis, Salmonella Typhimurium, and Escherichia coli O157:H7 are the most important foodborne pathogens, causing serious food poisoning outbreaks worldwide. Bacteriophages are increasingly considered as novel antibacterial agents to control foodborne pathogens. In this study, 8 Salmonella phages and 10 E. coli O157:H7 phages were isolated from chicken products. A polyvalent phage PS5 capable of infecting S. Enteritidis, S. Typhimurium, and E. coli O157:H7 was further characterized and its efficacy in reducing these foodborne pathogens was evaluated in in vitro and in foods. Morphology, one-step growth, and stability assay showed that phage PS5 was a myovirus, with relatively short latent periods, large burst sizes, and high stability. Genome sequencing analysis revealed that the genome of PS5 does not contain any genes associated to antibiotic resistance, toxins, lysogeny, and virulence factors. In broth, phage PS5 significantly decreased the viable counts of all the three bacterial hosts by more than 1.3 log CFU/mL compared to controls after 2 h of incubation at 4 °C and 24 °C. In foods, treatment with PS5 also resulted in significant reductions of viable counts of all the three bacterial hosts compared to controls at temperatures tested. This is the first report on single phage capable of simultaneously controlling S. Enteritidis, S. Typhimurium and E. coli O157:H7 in both in vitro and in foods.

DOI： 10.1016/j.foodres.2020.108977

Language：English   Publishing type：Research paper (scientific journal)  

We investigated the characteristics of Staphylococcus aureus isolates causing bovine subclinical mastitis (SCM), and their genetic relatedness with the isolates obtained from Egyptian cheese. Twenty-five S. aureus isolates were identified from 150 SCM milk and 75 cheese samples. The antibiogram revealed multidrug-resistant (MDR) isolates. Fifteen isolates were categorised as methicillin-resistant. Antimicrobial resistance and virulence genes were detected. Spa typing and SCCmec classification were performed. More than 50% of isolates were found carrying human-specific virulence determinants, while other isolates characterised were presumed to be of bovine-origin. Spa-types t304, t688, t084 corresponded isolates from SCM milk and cheese samples; the similar genotypes from SCM and cheese displayed divergence in virulence traits. Moreover, our results revealed the novel spa-type t18546. Animals and dairy food could be a reservoir for transformative changes in S. aureus virulence, leading to the emergence of virulent MDR strains that may become potential public-health threats.

DOI： 10.1016/j.idairyj.2020.104646

Language：English   Publishing type：Research paper (scientific journal)  

The pathogenicity of Salmonella Typhimurium, a foodborne pathogen, is mainly attributed to its ability to form biofilm on food contact surfaces. ε-polylysine, a polymer of positively charged lysine, is reported to inhibit biofilm formation of both gram-positive and gram-negative bacteria. To elucidate the mechanism underlying ε-polylysine-mediated inhibition of biofilm formation, the transcriptional profiles of ε-polylysine-treated and untreated Salmonella Typhimurium cells were comparatively analysed. The genome-wide DNA microarray analysis was performed using Salmonella Typhimurium incubated with 0.001% ε-polylysine in 0.1% Bacto Soytone at 30 °C for 2 h. The expression levels of genes involved in curli amyloid fibres and cellulose production, quorum sensing, and flagellar motility were downregulated, whereas those of genes associated with colanic acid synthesis were upregulated after treatment with ε-polylysine. The microarray results were validated by quantitative real-time polymerase chain reaction (qRT-PCR). Furthermore, treatment with ε-polylysine decreased the production of colanic acid in Salmonella Typhimurium. The findings of this study improved our understanding of the mechanisms underlying ε-polylysine-mediated biofilm inhibition and may contribute to the development of new disinfectants to control biofilm during food manufacturing and storage.

DOI： 10.1007/s00253-020-10575-2

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.3136/fstr.25.903

Language：English   Publishing type：Research paper (scientific journal)  

In this study, the antimicrobial resistance profiles of L. monocytogenes isolated from chicken meat in Fukuoka in 2017 were compared with the isolates of 2012. A total of 85 and 50 chicken meat samples, including different body parts, were collected from different supermarkets in Fukuoka in 2012 and 2017, respectively. Detection, isolation, identification, and characterization of L. monocytogenes were performed according to the conventional methods. Forty-five among 85 samples (53%) were positive for L. monocytogenes in 2012, while 12 among 50 samples in 2017 (24%) tested positive. One hundred fifty-three and 29 L. monocytogenes strains were isolated in 2012 and 2017, respectively. The serotypes of isolates in 2012 were 1/2a (21.5%), 1/2b (73.9%), 1/2c (1.5%), and 4b/4e (3.1%). In contrast, the 2017 isolates showed 1/2a (48.3%) and 1/2b (51.7%) serotypes. While all isolates in 2012 were positive for hlyA (listeriolysin O) in the PCR assay with hlyA primer set 7, only 17 hlyA positive isolates were seen in 2017. Moreover, 75 isolates with different ribotypes in 2012 and 29 isolates in 2017, respectively, were tested for antimicrobial susceptibility by broth microdilution for 18 different antimicrobial agents. Most of the 2012 and 2017 isolates displayed antimicrobial susceptibility. However, among the 2012 and 2017 isolates, 98.7% and 100% of the isolates were resistant to cefoxitin, 57.3% and 95.7% to fosfomycin, 72.0% and 82.6% to oxacillin, 8.0% and 17.4% to clindamycin, respectively. In addition, 2.7% of the isolates in 2012 were resistant to flomoxef and 4.3% of the isolates in 2017 to linezolid. Multidrug resistance (MDR) to 3 or more antimicrobials was observed in 35/75 (46.7%) isolates of 2012 and 19/23 (82.6%) in 2017. Detection of antimicrobial resistance (AMR) genes by PCR showed that the resistant isolates of 2012 were positive for mecA (96.3%) and ermC (83.3%), whereas the resistant isolates in 2017 screened positive for mecA (94.7%) and mefA (25.0%). Other cfxA, ermA, ermB, fosA, fosB, and fosC genes were absent in the PCR assay for any of the isolates. This study investigated for the first time the change in the L. monocytogenes contamination of chicken meat and antibiotic resistance of the isolated L. monocytogenes strains in Fukuoka, Japan, in the course of 5 years. Although the contamination rate of L. monocytogenes in 2017 was found to be lower than that in 2012, AMR of the isolates in 2017 was higher.

DOI： 10.1016/j.ijfoodmicro.2019.05.016

Language：English   Publishing type：Research paper (scientific journal)  

Shiga toxin-producing enterohaemorrhagic Escherichia coli (EHEC) O157:H7 is an important foodborne pathogen. Baicalein (5,6,7-trihydroxylflavone), a flavone isolated fromthe roots of Scutellaria baicalensis, is considered as a potential antibacterial agent to control foodborne pathogens. Among seven compounds selected by in silico screening of the natural compound database, baicalein inhibited the cytotoxicity of both Shiga toxins 1 and 2 (Stx1 and Stx2) against Vero cells after pretreatment at 0.13 mmol/L. In addition, baicalein reduced the susceptibility of Vero cells to both Stx1 and Stx2. Real-time qPCR showed that baicalein increased transcription of stx1 but not of stx2. However, baicalein had no effects on production or secretion of Stx1 or Stx2. Docking models suggested that baicalein formed a stable structure with StxB pentamer with low intramolecular energy. The results demonstrate that inhibitory activity of baicalein against the cytotoxicity of both Stx1 and Stx2 might be due to of the formation of a binding structure inside the pocket of the Stx1B and Stx2B pentamers.

DOI： 10.3390/toxins11090505

Language：English   Publishing type：Research paper (scientific journal)  

Sodium chloride maintains osmotic pressure of living cells including bacteria. Heat treatment is common for decontamination of bacteria in food. In this study, effects of NaCl on heat resistance of Salmonella Typhimurium were investigated. After cultivation in TSB containing 0.5% (TSB), 4% (4SC) and 8% (8SC) NaCl, S. Typhimurium cells were heated at 60 °C for 20 min. Total viable counts including intact cells and injured but recoverable cells determined by the plating method using TSA of S. Typhimurium cultured in 4SC and 8SC were significantly higher than those of the cells cultured in TSB. Meanwhile, changes of gene transcription were analyzed by DNA microarray. Transcription of genes involved in the colanic acid synthesis largely increased after cultivation in 4SC and 8SC. The amount of colanic acid significantly increased in the cells cultured in 4SC compared to that in M9-glucose medium. After recovery culture for 3 h, the genes involved in the phage shock response strongly up-regulated, suggesting contribution of these gene products in recovery of heat injured cells. The outcome of this study contributes to understand the mechanism of cross protection in Salmonella.

DOI： 10.1016/j.lwt.2019.02.056

Language：English   Publishing type：Research paper (scientific journal)  

Aim: The purpose of this study was to clarify the mechanism of the antibacterial action of two high potential and natural food additives, epigallocatechin gallate (EGCg) and theaflavin-3,3′-digallate (TF3), on Clostridium perfringens. Methods and Results: Minimal inhibitory concentrations were determined by the serial dilution method. Afterwards, the cells were treated with 250 or 1000 mg l
⁻¹
of EGCg and 125 or 500 mg l
⁻¹
of TF3 and morphological changes were observed and cell sizes were also measured under fluorescence microscopy. Our results showed that TF3 had a twice stronger antibacterial activity than EGCg against C. perfringens. Phase-contrast and fluorescence microscopy confirmed that the bacterial cells elongated without DNA segregation and septum formation in the presence of 250 mg l
⁻¹
EGCg. While in the higher concentration of EGCg and TF3, cell growth was suppressed. Bacterial cells reached to around 12 μm after the 24 h incubation with 250 mg l
⁻¹
EGCg, but the cells were shorter than the control at 1000 mg l
⁻¹
of EGCg. After washing and incubating the elongated cells in fresh medium, DNA segregated at 2 h of incubation. The average cell length decreased gradually and reached the normal size at 8 h. Conclusion: It seems that EGCg at a low concentration affected the proteins involved in the septum formation, DNA segregation and cell division. Furthermore, the high concentration of EGCg and TF3 seemed to cause stronger cellular damage to C. perfringens. Significance and Impact of the Study: These polyphenols are widely distributed in all higher plants especially in tea plants, and people tend to use natural food additives rather than synthetic ones. EGCg and TF3, as natural food additives, can prevent C. perfringens food poisoning along with other potential health benefits.

DOI： 10.1111/jam.14134

Language：English   Publishing type：Research paper (scientific journal)  

This study investigated the effect of epigallocatechin gallate (EGCg) on Staphylococcus aureus to determine its mechanism of antibacterial action. Adsorption of EGCg on the cell envelope of S. aureus after EGCg treatment was demonstrated using a FITC-labeled antibody specific to EGCg. After EGCg treatment of S. aureus for 4 h, abnormalities in septum formation and cell segregation were observed at concentrations greater than 250 mg/L, and debris presumed to arise from cell destruction or leakage of cytoplasmic materials was observed around the cells at 500 mg/L. Two-dimensional electrophoresis of proteins prepared from EGCg-treated S. aureus cells revealed the presence of 18 protein spots that disappeared or showed markedly decreased intensity compared to those from control cells. These proteins included DnaK, elongation factor G, DNA-directed RNA polymerase, l-lactate dehydrogenase, pyruvate dehydrogenase, and acetate kinase. Furthermore, S. aureus showed decreased glucose uptake after EGCg treatment. These results suggest that EGCg inhibits the functions of cell-envelope proteins, and it causes cellular damage and disruption of the cells in S. aureus.

DOI： 10.3136/fstr.25.277

Language：English   Publishing type：Research paper (scientific journal)  

Shiga toxin-producing Escherichia coli (STEC) O157:H7 and extended-spectrum beta-lactamase (ESBL) producing E. coli (ESBLEC) are important bacteria of public health concern and frequently isolated from raw beef products. Bacteriophage-based methods have been increasingly exploited to control bacterial contamination in meats. Here, we describe the isolation, characterization, and application of a lytic phage PE37 for the simultaneous bio-control of STEC O157:H7 and ESBLEC. Phage PE37, isolated from the bovine intestine, was morphologically characterized as a member of the Myoviridae family, with a broad host range and great stability under various stress conditions. Sequencing analysis revealed that the genomic DNA of phage PE37 contains genes that contribute to virion structure, replication, assembly, and host lysis. PE37 significantly reduced the viable counts of STEC O157:H7 by 4.9 and 2.6 log CFU/mL in broth after 6 h of incubation at 25 and 8 °C, respectively. Application of phage PE37 to raw beef artificially contaminated with STEC O157:H7 resulted in significant reductions in the viable counts by 2.3 and 0.9 log CFU/piece after 24 h of storage at 25 and 8 °C, respectively. Treatment of raw beef contaminated with a bacterial cocktail of STEC O157:H7 and ESBLEC with PE37 also significantly decreased the viable counts of the bacterial mixture by 1.4 and 1.0 log CFU/piece after 24 h of incubation at 25 and 8 °C, respectively. These findings suggest that bacteriophage PE37 may be a potential bio-agent for controlling STEC O157:H7 and ESBLEC contamination in raw beef.

DOI： 10.1007/s00253-018-9399-1

Language：English   Publishing type：Research paper (scientific journal)  

Sublethally heat-injured cells of Salmonella in food can recover under favorable conditions, leading to foodborne illness. To elucidate the molecular mechanism of recovery from heat injury, the global changes in gene transcription of Salmonella Typhimurium were investigated in previous study. In this study, the functions of genes involved in phage shock response（viz., phage shock protein（psp）genes）, the transcription levels of which were found in previous study to be increased during recovery from heat injury, were investigated in recovering cells. The increase in pspABCDEFG transcription levels during the recovery process was confirmed by qRT-PCR. To understand the role of psp genes in heat injury recovery, a pspA deletion mutant（ΔpspA）and a pspA-overexpressing strain（S. Typhimurium pBAD30/pspA（+））were constructed. ΔpspA showed slightly lower viable counts and membrane potential than those of the wild-type strain during recovery. On the other hand, there was no significant difference in the viable counts between S. Typhimurium pBAD30/pspA（+）and the control strains S. Typhimurium pBAD30/pspA （-）and S. Typhimurium pBAD30（+）during recovery. It would seem that a lack of PspA protein alone somewhat affects the recovery of S. Typhimurium from heat injury, but overexpression of PspA alone is not sufficient to overcome this effect.

DOI： 10.4265/bio.23.17

Language：English   Publishing type：Research paper (scientific journal)  

Aim: To analyse nutrition-adaptive multiple-bacteriocin production by Weissella hellenica QU 13. Methods and Results: Weissella hellenica QU 13 produces two leaderless bacteriocins, weissellicins Y and M. Their production was studied in MRS and APT media by quantification analyses with liquid chromatography mass spectrometry (LC/MS), while transcriptional analysis of biosynthetic genes was performed by real-time reverse transcription (RT)-PCR. Weissellicin Y production was higher in MRS culture than in APT culture, while weissellicin M production was higher in APT culture than in MRS culture. APT medium contains a higher amount of thiamine than MRS medium, to enhance the growth of heterofermentative lactic acid bacteria. Therefore, thiamine addition to MRS culture enhanced the growth of W. hellenica QU 13; consequently, weissellicin Y production was decreased, while weissellicin M production was not affected. Furthermore, real-time RT-PCR analyses indicated that the transcriptional trends of their respective structural genes, welY and welM, were different from each other, and that these two genes' transcriptions responded to nutrition conditions. Conclusion: Weissella hellenica QU 13 was demonstrated to control weissellicins Y and M production based on nutrition conditions. In addition, differential expression behaviour of weissellicins Y and M indicates that each of them would have separate roles to adapt to different environmental situations. Significance and Impact of the Study: This is the first report that describes nutrition-adaptive multiple-bacteriocin production, in which thiamine inhibits bacteriocin production while it enhances the growth of the producer strain.

DOI： 10.1111/jam.12997

Language：English   Publishing type：Research paper (scientific journal)  

A putative biosynthetic gene cluster of the enterocin NKR-5-3B (Ent53B), a novel circular bacteriocin, was analyzed by sequencing the flanking regions around enkB, the Ent53B structural gene, using a fosmid library. A region approximately 9 kb in length was obtained, and the enkB1, enkB2, enkB3, and enkB4 genes, encoding putative biosynthetic proteins involved in the production, maturation, and secretion of Ent53B, were identified. We also determined the identity of proteins mediating self-immunity against the effects of Ent53B. Heterologous expression systems in various heterologous hosts, such as Enterococcus faecalis and Lactococcus lactis strains, were successfully established. The production and secretion of the mature Ent53B required the cooperative functions of five genes. Ent53B was produced only by those heterologous hosts that expressed protein products of the enkB, enkB1, enkB2, enkB3, and enkB4 genes. Moreover, self-immunity against the antimicrobial action of Ent53B was conferred by at least two independent mechanisms. Heterologous hosts harboring the intact enkB4 gene and/or a combination of intact enkB1 and enkB3 genes were immune to the inhibitory action of Ent53B.

DOI： 10.1128/JB.00692-15

Language：English   Publishing type：Research paper (scientific journal)  

Enterococcus faecium NKR-5-3, isolated from Thai fermented fish, is characterized by the unique ability to produce five bacteriocins, namely, enterocins NKR-5-3A, -B, -C, -D, and -Z (Ent53A, Ent53B, Ent53C, Ent53D, and Ent53Z). Genetic analysis with a genome library revealed that the bacteriocin structural genes (enkA [ent53A], enkC [ent53C], enkD [ent53D], and enkZ [ent53Z]) that encode these peptides (except for Ent53B) are located in close proximity to each other. This NKR-5-3ACDZ (Ent53ACDZ) enterocin gene cluster (approximately 13 kb long) includes certain bacteriocin biosynthetic genes such as an ABC transporter gene (enkT), two immunity genes (enkIaz and enkIc), a response regulator (enkR), and a histidine protein kinase (enkK). Heterologous- expression studies of enkT and ΔenkT mutant strains showed that enkT is responsible for the secretion of Ent53A, Ent53C, Ent53D, and Ent53Z, suggesting that EnkT is a wide-range ABC transporter that contributes to the effective production of these bacteriocins. In addition, EnkIaz and EnkIc were found to confer self-immunity to the respective bacteriocins. Furthermore, bacteriocin induction assays performed with the ΔenkRK mutant strain showed that EnkR and EnkK are regulatory proteins responsible for bacteriocin production and that, together with Ent53D, they constitute a three-component regulatory system. Thus, the Ent53ACDZ gene cluster is essential for the biosynthesis and regulation of NKR-5-3 enterocins, and this is, to our knowledge, the first report that demonstrates the secretion of multiple bacteriocins by an ABC transporter.

DOI： 10.1128/AEM.02312-14

Language：English   Publishing type：Research paper (scientific journal)  

Biological functions of a DUF95 superfamily protein in the biosynthesis gene cluster of a novel circular bacteriocin, leucocyclicin Q (LcyQ), were characterized in this paper. Sequence analysis and database search of the regions flanking the LcyQ structural gene lcyQ revealed four open reading frames (lcyR, lcyB, lcyC, and lcyD) related to bacteriocin biosynthesis. LcyD shares some similarity to the DUF95 superfamily proteins, often found in the biosynthetic gene clusters of circular bacteriocins. Mass spectrometry analysis showed accumulation of active mature LcyQ inside lcyD knockout cells. Heterologous expression of lcyD demonstrated that it confers robust immunity against LcyQ. Peptide release/binding assay revealed that the immunity could be attributed to the secretion of LcyQ to the cell exterior. Thus, the DUF95 superfamily protein has a dual function in the biosynthesis of LcyQ, as an immunity-associated transporter and as a secretion-aiding agent. Accumulation of mature LcyQ inside the cell in lcyD knockout strains, further implied that cyclization occurs within the cell. To the best of our knowledge, this is the first report on LcyQ cyclization inside the cell and the dual role of a DUF95 superfamily protein in circular bacteriocin biosynthesis.

DOI： 10.1016/j.jbiosc.2013.06.023

Language：English   Publishing type：Research paper (scientific journal)  

Here, we report a new zinc-inducible expression system for Lactococcus lactis, called Zirex, consisting of the pneumococcal repressor SczA and P_czcD. P_czcD tightly regulates the expression of green fluorescent protein in L. lactis. We show the applicability of Zirex together with the nisin-controlled expression system, enabling simultaneous but independent regulation of different genes.

DOI： 10.1128/AEM.00866-13

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：鹿児島大学郡元キャンパス（鹿児島市）   Country：Japan  

Event date： 2022.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：⻑崎⼤学医学部ポンぺ会館（長崎市）   Country：Japan  

Event date： 2021.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン開催   Country：Japan  

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：鹿児島県医師会館４F大ホール（鹿児島市）   Country：Japan  

Event date： 2021.8

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：Japan  

Event date： 2021.6

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：United States  

Event date： 2019.9

Language：English  

Venue：Berlin   Country：Germany  

Event date： 2019.9

Language：English  

Venue：Berlin   Country：Germany  

Event date： 2019.8

Language：Japanese  

Venue：藤女子大学北16条キャンパス（札幌市）   Country：Japan  

Event date： 2019.7

Language：English   Presentation type：Oral presentation (general)  

Venue：SEC Centre（グラスゴー）   Country：United Kingdom  

Event date： 2018.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名城大学（愛知県名古屋市）   Country：Japan  

Event date： 2017.11

Language：Japanese  

Venue：タワーホール船堀（東京都江戸川区）   Country：Japan  

Event date： 2017.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Ernest N. Morial Convention Center   Country：United States  

Event date： 2017.6

Language：English  

Venue：Ernest N. Morial Convention Center   Country：United States  

Event date： 2023.8

Language：English   Presentation type：Oral presentation (general)  

Venue：京都女子大学（京都市東山区今熊野北日吉町35番地）   Country：Japan  

Event date： 2023.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：京都女子大学（京都市東山区今熊野北日吉町35番地）   Country：Japan  

Event date： 2023.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：京都女子大学（京都市東山区今熊野北日吉町35番地）   Country：Japan  

Event date： 2023.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：京都女子大学（京都市東山区今熊野北日吉町35番地）   Country：Japan  

Event date： 2023.8

Language：English  

Venue：京都女子大学（京都市東山区今熊野北日吉町35番地）   Country：Japan  

Event date： 2023.8

Language：English  

Venue：京都女子大学（京都市東山区今熊野北日吉町35番地）   Country：Japan  

Event date： 2023.8

Language：English  

Venue：京都女子大学（京都市東山区今熊野北日吉町35番地）   Country：Japan  

Event date： 2023.8

Language：English  

Venue：京都女子大学（京都市東山区今熊野北日吉町35番地）   Country：Japan  

Event date： 2023.8

Language：English  

Venue：京都女子大学（京都市東山区今熊野北日吉町35番地）   Country：Japan  

Event date： 2023.8

Language：English  

Venue：京都女子大学（京都市東山区今熊野北日吉町35番地）   Country：Japan  

Event date： 2023.8

Language：English  

Venue：京都女子大学（京都市東山区今熊野北日吉町35番地）   Country：Japan  

Event date： 2023.8

Language：English  

Venue：京都女子大学（京都市東山区今熊野北日吉町35番地）   Country：Japan  

Event date： 2023.8

Language：English  

Venue：京都女子大学（京都市東山区今熊野北日吉町35番地）   Country：Japan  

Event date： 2023.8

Language：English  

Venue：京都女子大学（京都市東山区今熊野北日吉町35番地）   Country：Japan  

Event date： 2023.8

Language：English  

Venue：京都女子大学（京都市東山区今熊野北日吉町35番地）   Country：Japan  

Event date： 2023.8

Language：English   Presentation type：Oral presentation (general)  

Venue：京都女子大学（京都市東山区今熊野北日吉町35番地）   Country：Japan  

Event date： 2023.8

Language：English   Presentation type：Oral presentation (general)  

Venue：京都女子大学（京都市東山区今熊野北日吉町35番地）   Country：Japan  

Event date： 2023.8

Language：English   Presentation type：Oral presentation (general)  

Venue：京都女子大学（京都市東山区今熊野北日吉町35番地）   Country：Japan  

Event date： 2023.8

Language：English   Presentation type：Oral presentation (general)  

Venue：京都女子大学（京都市東山区今熊野北日吉町35番地）   Country：Japan  

Event date： 2023.8

Language：English   Presentation type：Oral presentation (general)  

Venue：京都女子大学（京都市東山区今熊野北日吉町35番地）   Country：Japan  

Event date： 2023.8

Language：English   Presentation type：Oral presentation (general)  

Venue：京都女子大学（京都市東山区今熊野北日吉町35番地）   Country：Japan  

Event date： 2023.8

Language：English   Presentation type：Oral presentation (general)  

Venue：京都女子大学（京都市東山区今熊野北日吉町35番地）   Country：Japan  

Event date： 2023.8

Language：English   Presentation type：Oral presentation (general)  

Venue：京都女子大学（京都市東山区今熊野北日吉町35番地）   Country：Japan  

Event date： 2023.8

Language：English   Presentation type：Oral presentation (general)  

Venue：京都女子大学（京都市東山区今熊野北日吉町35番地）   Country：Japan  

Event date： 2023.7

Language：English  

Venue：CCH - Congress Center Hamburg(Congressplatz 1 20355 Hamburg Germany)   Country：Germany  

Event date： 2023.7

Language：English  

Venue：CCH - Congress Center Hamburg(Congressplatz 1 20355 Hamburg Germany)   Country：Germany  

Event date： 2023.7

Language：English   Presentation type：Oral presentation (general)  

Venue：COEX（513, Yeongdong-daero, Gangnam-gu Seoul 06164 Republic of Korea (06164)）   Country：Korea, Republic of  

Event date： 2023.7

Language：English   Presentation type：Oral presentation (general)  

Venue：COEX（513, Yeongdong-daero, Gangnam-gu Seoul 06164 Republic of Korea (06164)）   Country：Korea, Republic of  

Event date： 2023.7

Language：English  

Venue：COEX（513, Yeongdong-daero, Gangnam-gu Seoul 06164 Republic of Korea (06164)）   Country：Korea, Republic of  

Event date： 2023.7

Language：English  

Venue：COEX（513, Yeongdong-daero, Gangnam-gu Seoul 06164 Republic of Korea (06164)）   Country：Korea, Republic of  

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：鹿児島大学郡元キャンパス（鹿児島市）   Country：Japan  

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：鹿児島大学郡元キャンパス（鹿児島市）   Country：Japan  

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：鹿児島大学郡元キャンパス（鹿児島市）   Country：Japan  

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：鹿児島大学郡元キャンパス（鹿児島市）   Country：Japan  

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：鹿児島大学郡元キャンパス（鹿児島市）   Country：Japan  

Event date： 2022.11

Language：English   Presentation type：Oral presentation (general)  

Venue：鹿児島大学郡元キャンパス（鹿児島市）   Country：Japan  

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：鹿児島大学郡元キャンパス（鹿児島市）   Country：Japan  

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：鹿児島大学郡元キャンパス（鹿児島市）   Country：Japan  

Event date： 2022.6

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：WASHINGTON   Country：United States  

Event date： 2022.6

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：WASHINGTON   Country：United States  

Event date： 2021.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン開催   Country：Japan  

Event date： 2021.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：English   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：English   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：English   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：English   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：English   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：English   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.8

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：Japan  

Event date： 2021.6

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：United States  

Event date： 2021.6

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：United States  

Event date： 2021.6

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：United States  

Event date： 2021.6

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：United States  

Event date： 2021.6

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：United States  

Event date： 2021.6

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：United States  

Event date： 2021.6

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：United States  

Event date： 2020.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学西新プラザ   Country：Japan  

Event date： 2020.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学西新プラザ   Country：Japan  

Event date： 2020.6

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：United States  

Event date： 2020.6

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：United States  

Event date： 2020.6

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：United States  

Event date： 2020.6

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：オンライン   Country：United States  

Event date： 2019.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：沖縄県青年会館（那覇市）、琉球大学（沖縄県中頭郡）   Country：Japan  

Event date： 2019.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：沖縄県青年会館（那覇市）、琉球大学（沖縄県中頭郡）   Country：Japan  

Event date： 2019.11

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：米子コンベンションセンター BIG SHIP（米子市）   Country：Japan  

Event date： 2019.11

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：米子コンベンションセンター BIG SHIP（米子市）   Country：Japan  

Event date： 2019.9

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：千里ライフサイエンスセンター（大阪府豊中市）   Country：Japan  

Event date： 2019.9

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：千里ライフサイエンスセンター（大阪府豊中市）   Country：Japan  

Event date： 2019.8

Language：Japanese  

Venue：藤女子大学北16条キャンパス（札幌市）   Country：Japan  

Event date： 2019.8

Language：Japanese  

Venue：藤女子大学北16条キャンパス（札幌市）   Country：Japan  

Event date： 2019.8

Language：Japanese  

Venue：藤女子大学北16条キャンパス（札幌市）   Country：Japan  

Event date： 2019.8

Language：Japanese  

Venue：藤女子大学北16条キャンパス（札幌市）   Country：Japan  

Event date： 2019.8

Language：English   Presentation type：Oral presentation (general)  

Venue：九州大学西新プラザ（福岡市）   Country：Japan  

Event date： 2019.8

Language：English   Presentation type：Oral presentation (general)  

Venue：九州大学西新プラザ（福岡市）   Country：Japan  

Event date： 2019.7

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：北九州国際会議場（北九州市）   Country：Japan  

Event date： 2019.7

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：北九州国際会議場（北九州市）   Country：Japan  

Event date： 2019.7

Language：English   Presentation type：Oral presentation (general)  

Venue：SEC Centre（グラスゴー）   Country：United Kingdom  

Event date： 2019.7

Language：English   Presentation type：Oral presentation (general)  

Venue：SEC Centre（グラスゴー）   Country：United Kingdom  

Event date： 2019.7

Language：English   Presentation type：Oral presentation (general)  

Venue：SEC Centre（グラスゴー）   Country：United Kingdom  

Event date： 2019.6

Language：English  

Venue：Duke Energy Convention Center（オハイオ州シンシナティ）   Country：United States  

Event date： 2019.6

Language：English  

Venue：BITEC（バンコク）   Country：Thailand  

Event date： 2019.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京農業大学世田谷キャンパス（東京都世田谷区）   Country：Japan  

Functional analysis of galactinol synthase gene from Lactuca sativa in Escherichia coli

Event date： 2018.11

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：広島国際会議場（広島市）   Country：Japan  

Event date： 2018.11

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：広島国際会議場（広島市）   Country：Japan  

Event date： 2018.11

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：タワーホール船堀（東京都）   Country：Japan  

Event date： 2018.11

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：タワーホール船堀（東京都）   Country：Japan  

Event date： 2018.9

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：メルパルク京都（京都市）   Country：Japan  

Event date： 2018.9

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：メルパルク京都（京都市）   Country：Japan  

Event date： 2018.9

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：Freie Universität Berlin   Country：Germany  

Event date： 2018.9

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：Freie Universität Berlin   Country：Germany  

Event date： 2018.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Higashi-Senda Campus (Hiroshima City)   Country：Japan  

Event date： 2018.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Higashi-Senda Campus (Hiroshima City)   Country：Japan  

Event date： 2018.6

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：北九州国際会議場（北九州市）   Country：Japan  

Event date： 2018.6

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：北九州国際会議場（北九州市）   Country：Japan  

Event date： 2017.11

Language：English  

Venue：タワーホール船堀（東京都江戸川区）   Country：Japan  

Event date： 2017.11

Language：English  

Venue：タワーホール船堀（東京都江戸川区）   Country：Japan  

Event date： 2017.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：徳島県郷土文化会館（徳島市）   Country：Japan  

Event date： 2017.9

Language：Japanese  

Venue：千里ライフサイエンスセンター（大阪府豊中市）   Country：Japan  

Event date： 2017.9

Language：Japanese  

Venue：千里ライフサイエンスセンター（大阪府豊中市）   Country：Japan  

Event date： 2017.8

Language：English   Presentation type：Oral presentation (general)  

Venue：熊本大学（熊本市）   Country：Japan  

Event date： 2017.8

Language：English   Presentation type：Oral presentation (general)  

Venue：熊本大学（熊本市）   Country：Japan  

Event date： 2017.8 - 2018.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：日本大学湘南キャンパス（藤沢市）   Country：Japan  

Event date： 2017.7

Language：Japanese  

Venue：北九州国際会議場（北九州市）   Country：Japan  

Event date： 2017.7

Language：English  

Venue：北九州国際会議場（北九州市）   Country：Japan  

Event date： 2017.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：ウェスティン都ホテル京都／京都女子大学（京都府京都市）   Country：Japan  

Study on mechanism for inhibition of biofilm formation of Salmonella by food additive

Event date： 2017.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：ウェスティン都ホテル京都／京都女子大学（京都府京都市）   Country：Japan  

Analysis on the role of TA systems in E. coli heat tolerance

Event date： 2016.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：函館国際ホテル（北海道函館市）   Country：Japan  

Event date： 2016.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：函館国際ホテル（北海道函館市）   Country：Japan  

Event date： 2016.9

Language：Japanese  

Venue：きゅりあん（東京都品川区）   Country：Japan  

Event date： 2016.9

Language：Japanese  

Venue：きゅりあん（東京都品川区）   Country：Japan  

Event date： 2016.9

Language：Japanese  

Venue：きゅりあん（東京都品川区）   Country：Japan  

Event date： 2016.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：信州大学繊維学部（上田市）   Country：Japan  

cDNA cloning of cold-induced galactinol synthase genes from lettuce

Event date： 2016.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名城大学天白キャンパス（名古屋市）   Country：Japan  

Event date： 2016.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名城大学天白キャンパス（名古屋市）   Country：Japan  

Event date： 2015.12

Language：Japanese  

Venue：神戸   Country：Japan  

Event date： 2014.8 - 2014.9

Language：English  

Venue：Egmond aan Zee   Country：Netherlands  

Event date： 2014.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Lorient   Country：France  

Event date： 2013.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Verona   Country：Italy  

Event date： 2012.7

Language：English  

Venue：Nottingham   Country：United Kingdom  

Event date： 2011.8 - 2011.9

Language：English  

Venue：Egmond aan Zee   Country：Netherlands  

Event date： 2009.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Saint Malo   Country：France  

Event date： 2007.9

Language：English  

Venue：Fukuoka   Country：Japan  

Language：English   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)