Analysis Of Bacterial Diversity And Genetics Diversity Of Dominant Bacteria In Naturally Fermented Milk In Tajikistan

Natural fermented dairy products have a long history,which contain rich microbial resources.In this study,7 samples of naturally fermented milk collected from Tajikistan were taken as the experimental object.The biological diversity of lactic acid bacteria(LAB)in naturally fermented milk was analyzed by PacBio SMRT sequencing,and the LAB were isolated,identified and preserved.Finally,the genetics diversity of representative bacteria was analyzed.And the main results are as follows.(1)Based on the analysis of PacBio SMRT sequencing technology,it was found that the bacteria in naturally fermented milk in Tajikistan could be divided into 2 phyla,6genera and 15 species.Lactobacillus delbrueckii(82.02%)is the main bacterial strain in 7samples,also considered as the dominant strain are Streptococcus thermophilus(7.36%)and Lactobacillus helveticus(6.62%).Compared with the previous studies,the bacterial composition of naturally fermented milk in Tajikistan is relatively single,and Lactobacillus delbrueckii is the dominant.(2)89 strains of LAB were isolated from 7 samples,which were identified and classified into 3 genera and 7 species.Among them,Lactobacillus delbrueckii accounted for 88.76% of all isolates,which was the absolutely dominant strain in samples.In addition,Lactobacillus plantarum accounted for 3.37%,Enterococcus faecium accounted for 3.37%.(3)613 core gene sets and 11254 pan gene sets were constructed based on 43 representative strains of Lactobacillus delbrueckii combined with the published genomic data of 26 strains of NCBI.Further phylogenetic analysis divided Lactobacillus delbrueckii into three branches,located in different subspecies.They are Lactobacillus delbrueckii subsp.indicus,Lactobacillus delbrueckii subsp.lactis and Lactobacillus delbrueckii subsp.bulgaricus,also showed a certain regional aggregation.Among them,Lactobacillus delbrueckii subsp.indicus is distributed in Arka,Lactobacillus delbrueckii subsp.indicus and Lactobacillus delbrueckii subsp.lactis gather in Fapm,and Lactobacillus delbrueckii subsp.bulgaricus is mainly in Chad.In this study,the multiplex method was used to analyze the bacterial diversity in the samples of natural fermented milk from Tajikistan.89 strains of LAB were isolated,identified and preserved.The genetics diversity and species diversity of representative bacteria Lactobacillus delbrueckii in this region were revealed at the genome level.It provides reference data for the further development and utilization of LAB in naturally fermented dairy products.