Isolation and Identification of Oligosaccharide-metabolizing Lactic Acid Bacteria from Fermented Camel Milk in Xinjiang and an Analysis of Bacterial Flora Diversity

Fermented camel milk from Xinjiang serves as an excellent medium for cultivating lactic acid bacteria. To determine the diversity of lactic acid bacteria and bacterial communities in the fermented milk originating from different regions of Xinjiang, single-molecule real-time sequencing (SMRT) and microbial pure culture techniques were used to analyze nine milk samples from three regions of Xinjiang. Tee SMRT results revealed the rich and diverse compositions of bacterial communities among the different samples, identifying 899 genera and 158 species in total. In samples from the Dabancheng region, bacteria in the genera Lactobacillus (60.44%), Lactococcus (14.66%), and Raoultella (12.06%) were identified as being the most abundant, whereas Lactobacillus (32.27%), Lactococcus (28.86%), and Pseudomonas (12.56%) were found to predominate samples obtained from the Hami region, and Lactococcus (43.80%) and Serratia (16.01%) were identified as being predominant in samples from the Keping region. At the species level, Raoultella aquatica (12.06%), Pseudomonas fragi (7.50%), and Klebsiella oxytoca (6.67%) were established to be the most abundant in milk samples from Dabancheng, Hami, and Keping, respectively. Furthermore, using microbial pure culture methods to evaluate the metabolic capacities of 15 strains of lactic acid bacteria for xylo-oligosaccharides, fructo-oligosaccharides, inulin, and isomalto-oligosaccharides. And seven strains of lactic acid bacteria capable of metabolizing these four oligosaccharides were obtained through screening, of which, strains A-1, B-3, C-1, C-2, and C-5 were identified as Lactococcus lactis, and strains A-2 and B-1 were identified as isolates of Leuconostoc mesenteroides and Lactobacillus paracasei, respectively. These findings highlight clear regional differences in the structure of bacterial communities colonizing fermented camel milk in Xinjiang, and provide a theoretical basis and microbial resources for developing fermentation starters for this unique dairy product.