Whole-genome sequencing and probiotic potential analysis of Enterococcus durans B21 isolated from Tibetan kefir.

چکیده اصلی

To systematically evaluate the potential fermentation and probiotic-related properties of E. durans B21 isolated from kefir, this study integrated whole-genome sequencing, comparative genomics, genome-scale metabolic model (GEM) reconstruction, and in vitro phenotypic assays to comprehensively analyze its genetic characteristics, metabolic potential, safety, and probiotic-related functions. The results showed that E. durans B21 possesses a 3.14 Mb circular chromosome and three plasmids, with a total of 2935 predicted coding genes. The genome encodes 91 carbohydrate-active enzymes (CAZymes) and multiple lactose metabolism-related genes, indicating strong carbohydrate utilization potential. Comparative genomic analysis revealed high genomic similarity between B21 and the potential probiotic strain E. durans A8-1, and 27 probiotic-related functional genes were identified in B21. Additionally, the reconstructed GEM achieved a MEMOTE score of 86.7%. Flux balance analysis predicted that the strain could produce acetaldehyde and other flavor-related metabolites through lactose metabolism, which was experimentally validated by in vitro assays showing an acetaldehyde yield of 0.2137 mM in M17 medium. In vitro functional assays demonstrated that the strain exhibited certain tolerance to simulated intestinal fluid and bile salts, along with strong auto-aggregation and biofilm formation abilities. Nevertheless, multiple antimicrobial resistance-associated genes and several virulence-related factors were also identified in the genome, suggesting that its safety still requires further evaluation through antimicrobial resistance transferability analysis and animal experiments. Overall, E. durans B21 exhibits fermentation-associated and probiotic-related traits and may serve as a potential functional fermentation strain for further investigation.

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