Using hard cheese made from yak milk as the research subject,we isolated and identified amine-producing strains through selective media,amino acid decarboxylase tests,high-performance liquid chromatography,and 16S rDN...Using hard cheese made from yak milk as the research subject,we isolated and identified amine-producing strains through selective media,amino acid decarboxylase tests,high-performance liquid chromatography,and 16S rDNA analysis.Further,we investigated their biogenic amine production characteristics by altering pH,NaCl concentration,and free amino acid concentration.The results identified 10 amine-producing strains:6 Enterococcus durans strains,1 Enterococcus faecium strain,2 Lactococcus lactis strains,and 1 Leuconostoc mesenteroides strain.These strains produced tryptamine,phenethylamine,putrescine,cadaverine,and tyramine,with Enterococcus showing the highest amine production,reaching 1439 mg/L.The environmental conditions had varying effects on the strains.The amino acid concentration has the greatest impact on the amine production capacity of Enterococcus and Enterococcus faecium,followed by pH,with salt content having the least effect.The lowest amine production was observed at a pH of 6,while Enterococcus exhibited the highest amine production of 1773.74 mg/L at an amino acid concentration of 2 g/L.The biogenic amine content of Lactococcus lactis showed significant increases with rising salt and amino acid concentrations.Amino acid concentration significantly impacted the amine production ability of Leuconostoc mesenteroides,with biogenic amine content increasing significantly as amino acid concentration rose.However,high salt concentrations inhibited its growth and amine production ability.展开更多
The changes in microbial composition of salmon slices during storage at 4◦C were measured using high-throughput sequencing(HTS),and biogenic amine(BA)-producing bacteria were isolated from salmon slices to evaluate th...The changes in microbial composition of salmon slices during storage at 4◦C were measured using high-throughput sequencing(HTS),and biogenic amine(BA)-producing bacteria were isolated from salmon slices to evaluate their ability to produce BAs.Fresh salmon slices had the highest bacterial diversity,which decreased with the extension of the refrigerated storage time.Phenylobacterium was the dominating genus in fresh salmon slices,followed by Photobacterium and Burkholderia,while Brochothrix became the dominant bacterium in the later stages of the storage period.Seven strains of BA-producing bacteria were isolated and determined,which varied greatly in BA production.Among these,Brochothrix thermosphacta(B5)exhibited the strongest BA-producing ability,producing 98.32 mg/mL of putrescine and 78.81 mg/mL of cadaverine,and Photobacterium phosphoreum showed a stronger histamine-producing ability(77.07 mg/mL).This study explored the microbial composition in salmon slices and offer insight into the relationship between microorganisms and BAs in salmon slices.This study provides a theoretical basis for developing antibacterial agents,decreasing the amount BAs,and extending the shelf-life of salmon slices.展开更多
In-depth knowledge of the microbes responsible for biogenic amine(BA)production during soy sauce fermentation remains limited.Herein,the variations in the BA profiles,microbial communities,and microbes involved in BA ...In-depth knowledge of the microbes responsible for biogenic amine(BA)production during soy sauce fermentation remains limited.Herein,the variations in the BA profiles,microbial communities,and microbes involved in BA production during the fermentation of soy sauce through Japanese-type(JP)and Cantonese-type(CP)processes were compared.BA analysis revealed that the most abundant BA species were putrescine,tyramine,and histamine in the later three stages(1187.68,785.16,and 193.20 mg/kg on average,respectively).The BA profiles differed significantly,with CP samples containing higher contents of putrescine,tyramine,and histamine(P<0.05)at the end of fermentation.Metagenomic analysis indicated that BA-producing genes exhibited different abundance profiles,with most genes,including spe A,spe B,arg,spe E,and tyr DC,having higher abundances in microbial communities during the CP process.In total,15 high-quality metagenome-assembled genomes(MAGs)were retrieved,of which 10 encoded at BA production-related genes.Enterococcus faecium(MAG10)and Weissella paramesenteroides(MAG5)might be the major tyramine producers.The high putrescine content in CP might be associated with the high abundance of Staphylococcus gallinarum(MAG8).This study provides a comprehensive understanding of the diversity and abundance of genes involved in BA synthesis,especially at the species level,during food fermentation.展开更多
基金the National Natural Science Foundation of China for providing us with financial support(grant number:31860449).
文摘Using hard cheese made from yak milk as the research subject,we isolated and identified amine-producing strains through selective media,amino acid decarboxylase tests,high-performance liquid chromatography,and 16S rDNA analysis.Further,we investigated their biogenic amine production characteristics by altering pH,NaCl concentration,and free amino acid concentration.The results identified 10 amine-producing strains:6 Enterococcus durans strains,1 Enterococcus faecium strain,2 Lactococcus lactis strains,and 1 Leuconostoc mesenteroides strain.These strains produced tryptamine,phenethylamine,putrescine,cadaverine,and tyramine,with Enterococcus showing the highest amine production,reaching 1439 mg/L.The environmental conditions had varying effects on the strains.The amino acid concentration has the greatest impact on the amine production capacity of Enterococcus and Enterococcus faecium,followed by pH,with salt content having the least effect.The lowest amine production was observed at a pH of 6,while Enterococcus exhibited the highest amine production of 1773.74 mg/L at an amino acid concentration of 2 g/L.The biogenic amine content of Lactococcus lactis showed significant increases with rising salt and amino acid concentrations.Amino acid concentration significantly impacted the amine production ability of Leuconostoc mesenteroides,with biogenic amine content increasing significantly as amino acid concentration rose.However,high salt concentrations inhibited its growth and amine production ability.
基金This work was supported by the National Key Research and Development Program of China(Grant Number 2019YFD0901702).
文摘The changes in microbial composition of salmon slices during storage at 4◦C were measured using high-throughput sequencing(HTS),and biogenic amine(BA)-producing bacteria were isolated from salmon slices to evaluate their ability to produce BAs.Fresh salmon slices had the highest bacterial diversity,which decreased with the extension of the refrigerated storage time.Phenylobacterium was the dominating genus in fresh salmon slices,followed by Photobacterium and Burkholderia,while Brochothrix became the dominant bacterium in the later stages of the storage period.Seven strains of BA-producing bacteria were isolated and determined,which varied greatly in BA production.Among these,Brochothrix thermosphacta(B5)exhibited the strongest BA-producing ability,producing 98.32 mg/mL of putrescine and 78.81 mg/mL of cadaverine,and Photobacterium phosphoreum showed a stronger histamine-producing ability(77.07 mg/mL).This study explored the microbial composition in salmon slices and offer insight into the relationship between microorganisms and BAs in salmon slices.This study provides a theoretical basis for developing antibacterial agents,decreasing the amount BAs,and extending the shelf-life of salmon slices.
基金supported by the Natural Science Foundation of Guangdong Province(2022A1515012158)the National Science Foundation of China(41977138)+3 种基金the Construction Project of Teaching Quality and Teaching Reform in Guangdong Province(SJD202001)the General University Project of Guangdong Provincial Department of Education(2021KCXTD070 and 2021ZDZX4072)the Key Project of Social Welfare and Basic Research of Zhongshan City(2020B2010)the Start-up Fund from the Zhongshan Institute at the University of Electronic Science and Technology in China(419YKQN12)。
文摘In-depth knowledge of the microbes responsible for biogenic amine(BA)production during soy sauce fermentation remains limited.Herein,the variations in the BA profiles,microbial communities,and microbes involved in BA production during the fermentation of soy sauce through Japanese-type(JP)and Cantonese-type(CP)processes were compared.BA analysis revealed that the most abundant BA species were putrescine,tyramine,and histamine in the later three stages(1187.68,785.16,and 193.20 mg/kg on average,respectively).The BA profiles differed significantly,with CP samples containing higher contents of putrescine,tyramine,and histamine(P<0.05)at the end of fermentation.Metagenomic analysis indicated that BA-producing genes exhibited different abundance profiles,with most genes,including spe A,spe B,arg,spe E,and tyr DC,having higher abundances in microbial communities during the CP process.In total,15 high-quality metagenome-assembled genomes(MAGs)were retrieved,of which 10 encoded at BA production-related genes.Enterococcus faecium(MAG10)and Weissella paramesenteroides(MAG5)might be the major tyramine producers.The high putrescine content in CP might be associated with the high abundance of Staphylococcus gallinarum(MAG8).This study provides a comprehensive understanding of the diversity and abundance of genes involved in BA synthesis,especially at the species level,during food fermentation.
