Dynamic changes and functional analysis of the vaginal microbial communities in reproductively dysfunctional giant pandas.

Maintaining reproductive health in female giant pandas is vital for sustaining population growth. In clinical practice, we have observed reproductive dysfunction (defined as repeated mating failure accompanied by reproductive cycle irregularities) in some individuals. This study investigated the association between reproductive dysfunction and the vaginal microbiota in 15 captive pandas, using 16S rDNA sequencing and biochemical analyses. Reproductively dysfunctional pandas (n = 6) exhibited reduced serum albumin, elevated creatine kinase, increased white blood cell count and mean corpuscular haemoglobin, and decreased monocytes, indicating disturbances in protein metabolism, energy homeostasis, and immune regulation. Vaginal microbiotal analysis revealed consistent dominant taxa at phylum to genus levels between dysfunctional and functional pandas, but only 7.89% shared amplicon sequence variants. The dysfunctional pandas had significantly higher flora richness (Chao1 index) and distinct community structure (principal coordinates analysis first component explaining 18.2% variation (Adonis P < 0.001), characterised by the enrichment of opportunistic pathogens (Bifidobacterium, Klebsiella) and depletion of health-associated genera (Helcococcus, Peptoniphilus). Elevated Klebsiella abundance suggested microecological imbalance. Functional annotation identified activated carbohydrate/pyruvate metabolism, ABC transporter pathways, and GABAergic synaptic signaling in dysfunctional microbiota, with key gene abundances (K00196, K02645) positively correlated with enriched genera. The results indicate that reproductive dysfunction in giant pandas corresponds with distinctive changes in vaginal microbial composition and functional activity, with Klebsiella enrichment and energy metabolism pathway activation serving as potential microbial markers. This study provides a microecological basis for understanding the pathogenesis of reproductive dysfunction in this endangered species.