Biodiversity of lactic acid bacteria isolated from fermented milk products in Xinjiang,China

Fermented dairy products have been produced and consumed for thousands of years in Xinjiang, China. In this study, traditional culture-dependent methods and 16S rRNA gene analyses were performed to analyze the composition of lactic acid bacteria (LAB) from 86 samples of traditional fermented dairy products collected from four regions of Xinjiang. Quantitative polymerase chain reaction (qPCR) was used to quantify Bifidobacterium and Lactobacillus species. The LAB isolates (N = 705) were identified as belonging to seven genera and 26 species or subspecies. The predominant species of all isolates were Lactobacillus (Lb.) delbrueckii subsp. bulgaricus, Lb. fermentum, and Lb. helveticus. The LAB counts of these samples ranged from 5.35 to 10.06 Log CFU/mL. The bacterial counts of seven lactobacilli species and Bifidobacterium ranged from 0.98 ± 0.14 Log CFU/mL (for Lb. sakei from fermented mare milk) to 9.91 ± 0.17 Log CFU/mL (for Lb. helveticus from fermented mare milk). While the microbiota was significantly different between yak and cow milk, there was no significant difference between the Tex and Zhaosu counties. In conclusion, LAB communities in traditional fermented dairy products are complex and differ among local regions within Xinjiang.     

Using PacBio sequencing to investigate the bacterial microbiota of traditional Buryatian cottage cheese and comparison with Italian and Kazakhstan artisanal cheeses

Traditional fermented dairy foods including cottage cheese have been major components of the Buryatia diet for centuries. Buryatian cheeses have maintained not only their unique taste and flavor but also their rich natural lactic acid bacteria (LAB) content. However, relatively few studies have described their microbial communities or explored their potential to serve as LAB resources. In this study, the bacterial microbiota community of 7 traditional artisan cheeses produced by local Buryatian families was investigated using single-molecule, real-time sequencing. In addition, we compared the bacterial microbiota of the Buryatian cheese samples with data sets of cheeses from Kazakhstan and Italy. Furthermore, we isolated and preserved several LAB samples from Buryatian cheese. A total of 62 LAB strains (belonging to 6 genera and 14 species or subspecies) were isolated from 7 samples of Buryatian cheese. Full-length 16S rRNA sequencing of the microbiota revealed 145 species of 82 bacterial genera, belonging to 7 phyla. The most dominant species was Lactococcus lactis (43.89%). Data sets of cheeses from Italy and Kazakhstan were retrieved from public databases. Principal component analysis and multivariate ANOVA showed marked differences in the structure of the microbiota communities in the cheese data sets from the 3 regions. Linear discriminant analyses of the effect size identified 48 discriminant bacterial clades among the 3 groups, which might have contributed to the observed structural differences. Our results indicate that the bacterial communities of traditional artisan cheeses vary depending on geographic origin. In addition, we isolated novel and valuable LAB resources for the improvement of cottage cheese production.