Isolation And Identification Of Lactic Acid Bacteria And Microbial Diversity In Xilin Gol Fresh Milk And Yogurt

Traditional dairy products in Inner Mongolia have a long history,rich nutrition and contain a large number of probiotic lactic acid bacteria resources.It is urgent to further analyze the microbial diversity of traditional dairy products and complete the protection of lactic acid bacteria.Therefore,in this paper,10 fresh milk and 19 yogurt samples from Xilin Gol ethnic gathering places were collected for metagenomic sequencing analysis to analyze their microbial diversity,and lactic acid bacteria were isolated and identified in combination with traditional culture methods.The main contents include:(1)Lactic acid bacteria isolation and identification.A total of 338 strains were isolated from 29 samples.135 strains were isolated from fresh milk samples and the dominant strains were Lactococcus lactis(45%)and Enterococcus faecalis(12%).A total of 203 strains were isolated from yogurt samples,and the dominant strains were Lactococcus lactis(54%)and Lactobacillus plantarum(9%).(2)Microbial diversity analysis of fresh milk and yogurt.A total of 8 phyla,141 genera and 292 species were identified based on metagenomic technology.The dominant strains of fresh milk were Lactococcus lactis and Lactococcus ul36,and the dominant strains of yoghurt were Lactococcus lactis and Lactobacillus equi.There were more common microorganisms between fresh milk and yogurt,and there was no significant difference in α diversity,but there were still abundant different species in the samples of the two groups,including Vibrio subspecies Ex25 in fresh milk and lactococcus phage 1706 in yogurt.(3)Microbial functional pathway analysis of fresh milk and yogurt.Based on Uniprot database,1408048 genes and 507 metabolic pathways were annotated,among which amino acid biosynthesis,hydrochloride degradation and carboxylic aldehyde degradation were the main metabolic pathways in fresh milk.Teichoic acid-polyglycerol biosynthesis,phosphate ester biosynthesis and leukotriene biosynthesis are the main metabolic pathways in yogurt.(4)Difference analysis of dairy microorganism in 4 banner counties of Xilin Gol.The number of isolates in Lanqi and Baiqi dairy products was significantly higher than that in East Wujumuqin Banner.The dominant strains of dairy products in different counties were Lactococcus lactis and Lactobacillus plantarum,and the main functional pathway was6-hydroxymethyl dihydropterin diphosphate biosynthesis.There were endemic species in each banner,including enterobacter bacteriophage CC31 in Lanqi,Leuconostoc lactobacillus in Baiqi,Heishwanella in Sunit left Banner,and Enterobacter MGH8 in East Wuzhumuqin Banner,showing certain geographical differences.(5)Microbial difference analysis of 8 representative household dairy products.The dominant strain of different household dairy products was Lactococcus lactis,and the main functional pathway was still 6-hydroxymethyldihydropterin diphosphate biosynthesis.The dominant strains in the close families were consistent,and each family had its own specific strains and functional pathways.This study is expected to provide theoretical basis for the safe production of traditional dairy products and the development of starter culture.