Characteristics Of Microbial Community Structure And Discovery Of Functional Microorganisms In Traditional Fermented Sour Soup In Guizhou Province

This study focuses on exploring the characteristics of microbial community structure in sour soup in Kaili City,Guizhou Province,and analyzing it.Lactobacillus Isolated from sour soup was used to optimize the fermentation conditions of sour soup.In addition,the antioxidant and antibacterial activities of Lactobacillus fermentation supernatant were detected to evaluate its antioxidant and antibacterial ability in vitro.Combined with the results of real-time fluorescent quantitative PCR,the expression differences of bacteriocin related genes under different Na Cl concentrations were identified,which provided a theoretical basis for the regulation of bacteriocin synthesis.The specific research contents and results are as follows(1)High throughput sequencing technology was used to explore the microbial community structure of sour soup in Kaili City,Guizhou Province.The total genomic DNA was extracted from the sour soup samples collected in Kaili City,Guizhou Province.The results showed that the dominant phylum was Firmicutes(70.0%).At the level of genus classification,there were similar dominant genera in the community structure of all samples,mainly Lactobacillus(52.8%).(2)By analyzing the 16S rRNA gene sequence of bacteria,116 strains were isolated from Kaili sour soup in Guizhou Province,mainly Lactobacillus.(3)Lactobacillus Isolated from sour soup with strong acid producing ability was selected to optimize the fermentation process of tomato sour soup.The fermentation end point of sour soup was determined by sensory evaluation,and the amount of bacteria in sour soup was 1×10~6 cfu/g,the sour soup with 37?fermentation temperature,3%Na Cl content and multi strain fermentation was more acceptable.(4)The antioxidant activity of Lactobacillus fermentation supernatant in vitro was evaluated.It was found that Lactobacillus fermentation supernatant had good scavenging activity on DPPH and hydroxyl radicals,and the highest scavenging activity was more than 99%.Lactobacillus can secrete a variety of antibacterial substances,which can effectively inhibit the growth and reproduction of spoilage bacteria.Lactobacillus Isolated from sour soup is used to inhibit spoilage bacteria and Escherichia coli isolated from sour soup.It is found that the fermentation supernatant of lactobacillus has a good inhibitory effect on Escherichia coli.The main antibacterial substances were organic acids and bacteriocins.The fermentation supernatant still had antibacterial activity after high temperature treatment for 1 h.The expression of bacteriocin related genes in Lactobacillus under salt stress was detected by real-time fluorescent quantitative PCR.