Isolation And Identification Of Lactic Acid Bacteria And Diversity Research In Naturally Fermented Dairy Products From Kyrgyzstan

Kyrgyzstan has a vast territory,where the local animal husbandry and agriculture are advanced.Fermented dairy products are the most important part of the local residents' diet.Naturally fermented dairy products contain abundant lactic acid bacteria resources which are recognized as safe edible strains.However,there are a few researches on the bacterial composition of naturally fermented dairy products in this area,especially the composition of lactic acid bacteria.It is of great significance to study the bacterial diversity of naturally fermented dairy products in Kyrgyzstan for understanding the bacterial composition of them.In this study,29 naturally fermented dairy products from Kyrgyzstan were selected as the research objects,including 14 samples of yoghurt,10 samples of koumiss and 5 samples of cheese.The strains of lactic acid bacteria were isolated by pure culture method,and the full-length 16S rRNA gene sequence of bacteria in 29 naturally fermented dairy products were sequenced by PacBio SMRT.The main results of this paper were as follows.First,the total viable count of lactic acid bacteria in 29 naturally fermented dairy products were 6.80×105 CFU/mL to 3.04×109 CFU/mL.The total viable count of lactic acid bacteria in yoghurt samples were 3.85×107 CFU/mL to 3.00×109 CFU/mL,the total viable count of lactic acid bacteria in koumiss samples and chesse samples were 6.80×105 CFU/mL to 3.04×109 CFU/mL and 1.19×109 CFU/mL.Second,209 strains of lactic acid bacteria from 29 naturally fermented dairy products were isolated by pure culture method.These strains were identified as 3 genus,11 species by 16S rRNA gene sequence analysis and homology comparison.Among them,Lactococcus lactis were isolated in naturally fermented yoghurt samples,Lactobacillus harbinensis and Leuconostoc mesenteroides were isolated in naturally fermented koumiss samples.Lactobacillus delbrueckii were isolated from the naturally fermented cheese samples.Third,the bacterial composition and biodiversity were analyzed by PacBio SMRT sequencing technology.A total of 48 species,24 genus and 4 phylum were detected in 29 naturally fermented dairy products from Kyrgyzstan.Among these,Lactobacillus delbrueckii(45.28%)were the most dominant bacterial species in the samples of naturally fermented yoghurt samples,Lactobacillus helveticus(53.90%),and Lactobacillus delbrueckii(58.17%)were the most dominant bacterial species in the samples of naturally fermented koumiss samples and cheese samples.The results showed that different naturally fermented dairy products contained different numbers and types of bacteria.Based on the combination of pure culture and PacBio SMRT sequencing technology,we can fully understand the bacterial diversity of naturally fermented dairy products in Kyrgyzstan,which provides a reference for the development of lactic acid bacteria in naturally fermented dairy products and the research of bacterial diversity.