Analysis Of Bacterial Community Structure And Performance Of Lactic Acid Bacteria Of Qula In Gannan

Qula is a traditional fermented dairy product made by Tibetan herdsmen.Qula produced by traditional fermentation contains abundant microbial resources.Therefore,it is of great significance to comprehensively study the microbial diversity and lactobacillus performance of Qula for the quality improvement and comprehensive utilization of its products.This study in Gansu province in Gannan Tibetan herdsmen family traditional hand-made samples of Qula as the research object,by using high-throughput sequencing technologies emerging bacterial diversity and community structure in the Qula is analyzed,and through traditional training methods of lactic acid bacteria isolation and identification of Qula and study the performance of the Qula in lactic acid bacteria.Through research findings:(1)Bacterial 16S rRNA gene sequencing of Qula samples showed that the bacterial community structure of Qula samples from different sources was different.Firmicutes and Proteobacteria were the dominant phyla,Lactobacillus,Acetobacter and Lactococcus were the dominant genus.Functional gene prediction of bacteria showed that there were differences among bacterial communities of Qula samples from different sources.(2)There are 97 strains of lactic acid bacteria were isolated from 9 Qula fermented.And 6 strains of lactic acid bacteria were preliminarily screened and identified by 16S rDNA,strain Q1 was Streptococcus thermophilus,strain Q2 was Enterococcus durans,strains G1,G2,G3,and G4 were Lactobacillus helveticus.(3)Research on strain fermentation and live performance,6 strains of lactic acid bacteria curd time between 4~7h,curd titratable acidity in between 73.42~89.38°T change,cold storage period acidity increased by 14.22~20.93°T,number of living bacterium were greater than 10~7 CFU/mL,viscosity of 5.42~7.84 Pa·s,strain G2,G4,Q1 has good tolerance.(4)The results showed that the 6 strains of lactic acid bacteria produced 60 kinds of volatile flavor substances,and the composition and content of the flavor substances produced by the fermentation of different strains of lactic acid bacteria were different.The strain G1had strong ability to produce 2-heptanone.Strain G1 and Q1 had strong ability to produce isoamyl alcohol and caproic acid.Strain G2 had higher yield of acetoin,furfuryl alcohol and2-tridecone than other strains.The strain G4 had strong ability to produce acetic acid and butyric acid.In summary,the analysis of bacterial community structure can provide a theoretical basis for the comprehensive utilization and food safety of the control.The isolated lactic acid bacteria have the potential to prepare the starter,and the research results can provide a theoretical basis for the application of lactic acid bacteria.