Isolation, Identification and Comparative Genomic Analysis of Lactobacillus salivarius from Mongolian Horse Vagina

Yiping ZhaoYuanyi Liu^*Jinshan TaoJialong CaoYanan LinQianqian HeXinlan FangSiqin YunMing DuShaofeng SuTugeqin BaoDongyi BaiXinzhuang ZhangManglai Dugarjaviin^*

• Inner Mongolia Agricultural University, Hohhot, China

Reproductive health in mares is critical for the sustainability of the equine industry. However, vaginal microbiota dysbiosis remains a neglected contributor to infections, such as endometritis and bacterial vaginosis. While Lactobacillus spp. dominate healthy vaginal ecosystems in humans and livestock, their role in equine reproductive health—particularly in resilient breeds like Mongolian mares—is poorly understood. This study isolated and characterized a novel Lactobacillus salivarius strain (Y20) from the vaginal microbiota of healthy Mongolian mares using a polyphasic approach integrating phenotypic, biochemical, and 16S rRNA gene sequencing. The probiotic potential of Y20 was evaluated through in vitro assays, demonstrating robust tolerance to low pH (pH 2.5) and bile salts (0.3%), potent antagonistic activity against equine pathogens (Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa), and significant antioxidant capacity (82.4% DPPH radical scavenging). Whole-genome sequencing (1.74 Mb, 33.01% GC content) revealed genes encoding carbohydrate metabolism, adhesion factors, bacteriocin biosynthesis (including a novel putative bacteriocin cluster), and stress response pathways. Comparative genomics highlighted Y20’s close phylogenetic relationship with horse-derived Lactobacillus salivarius strains and unique genomic adaptations for vaginal colonization. These findings identify Lactobacillus salivarius Y20 as a candidate probiotic for mitigating equine reproductive disorders, offering a sustainable alternative to antibiotics and advancing microbiome-based strategies for equine health management.