Diversity Of Bacteria In Naturally Fermented Milk And Koumiss From Uzbekistan

Uzbekistan is a multi-ethnic country located in the middle of Central Asia.Traditional fermented dairy products are the most important part of local residents'diet structure.Samples were collected in order to reveal the composition of lactic acid bacteria(LAB)and bacterial diversity in naturally fermented milk and koumiss from Uzbekistan.Pure culture method was performed to obtain the strains of LAB.The composition and abundance of bacteria in these samples were analyzed by PacBio SMRT sequencing technology.The research results are as follows:A total of 31 samples of traditional fermented dairy products were collected from two locations in Uzbekistan,and the viable count of LAB in most samples was more than 10~7CFU/m L.It indicated that the abundance of LAB in naturally fermented milk and koumiss was relatively high in this area.A total of 181 strains were isolated from 31 samples by pure culture method.Through16S r RNA gene sequence alignment,all the strains belonged to 3 genera,which contained8 species.Lactobacillus delbrueckii(85%)was the predominant species of 31 samples.The majority of LAB isolates from naturally fermented milk was Lactobacillus delbrueckii,accounting for 94%of total isolates in naturally fermented milk.The dominant LAB isolates from koumiss was Lactobacillus helveticus,accounting for 63%of total isolates in koumiss.PacBio SMRT sequencing results showed that a total of 127 bacterial species were detected from these samples belong to 86 genera and 12 phyla.Among which,the predominant species was Lactobacillus delbrueckii with a relative content of 50%.The dominant bacteria phylum and genus of naturally fermented milk and koumiss were the same,which were Firmicutes and Lactobacillus respectively.The most abundant species of naturally fermented milk and koumiss were Lactobacillus delbrueckii(56%)and Lactobacillus helveticus(78%)respectively.According to the principal coordinate analysis(PCo A),naturally fermented milk samples were obviously clustered together and koumiss samples were also clustered together,while traditional fermented dairy products of the different types were obviously separated.In this study,the bacterial diversity of naturally fermented milk and koumiss in Uzbekistan was fully revealed by the combination of pure culture method and PacBio SMRT sequencing technology.It is not only of great significance for culture collection of LAB resources,but also provides some theoretical data to improve quality and expand production of traditional dairy products.