Sufu,a traditional fermented soybean curd,is prone to contamination by Bacillus cereus.In this study,133 lactic acid bacteria(LAB)strains were initially screened from spring and winter Mao-tofu samples for their abili...Sufu,a traditional fermented soybean curd,is prone to contamination by Bacillus cereus.In this study,133 lactic acid bacteria(LAB)strains were initially screened from spring and winter Mao-tofu samples for their ability to inhibit the growth of B.cereus ATCC 14579T.Among these strains,five Lactococcus lactis strains exhibited a good safety profile and were capable of growing in pH 4-9 and salt concentrations of 6%-8%.Antimicrobial experiments conducted on the B.cereus group from sufu factories showed that L.lactis LJL7m20 strain had the strongest inhibitory effect.Whole-genome sequencing revealed the presence of three genes associated with high osmotic stress response and eight distinct two-component systems that may contribute to the strain’s tolerance,enhancing its survival in high-salt environments.The strain was further identified as L.lactis subsp.lactis through a combination of phenotypic and genotypic analysis.Additionally,bacteriocins nisin Z and nisin A/Q were identified using the BAGEL4 and antiSMASH databases.ELISA further confirmed the strain’s ability to produce nisin.A fermentation validation study demonstrated that inoculation with the strain contributed to reduce the number of B.cereus group in sufu pehtzes.This study provides a theoretical foundation for the use of new biocontrol bacteria to improve the safety of traditional fermented soybean foods.展开更多
基金supported by the Guangdong Major Project of Basic and Applied Basic Research[grant numbers 2020B0301030005].
文摘Sufu,a traditional fermented soybean curd,is prone to contamination by Bacillus cereus.In this study,133 lactic acid bacteria(LAB)strains were initially screened from spring and winter Mao-tofu samples for their ability to inhibit the growth of B.cereus ATCC 14579T.Among these strains,five Lactococcus lactis strains exhibited a good safety profile and were capable of growing in pH 4-9 and salt concentrations of 6%-8%.Antimicrobial experiments conducted on the B.cereus group from sufu factories showed that L.lactis LJL7m20 strain had the strongest inhibitory effect.Whole-genome sequencing revealed the presence of three genes associated with high osmotic stress response and eight distinct two-component systems that may contribute to the strain’s tolerance,enhancing its survival in high-salt environments.The strain was further identified as L.lactis subsp.lactis through a combination of phenotypic and genotypic analysis.Additionally,bacteriocins nisin Z and nisin A/Q were identified using the BAGEL4 and antiSMASH databases.ELISA further confirmed the strain’s ability to produce nisin.A fermentation validation study demonstrated that inoculation with the strain contributed to reduce the number of B.cereus group in sufu pehtzes.This study provides a theoretical foundation for the use of new biocontrol bacteria to improve the safety of traditional fermented soybean foods.
