are major contributors of sialidases in the human vaginal microbiome.

Elevated bacterial sialidase activity in the female genital tract is strongly associated with poor health outcomes including preterm birth and bacterial vaginosis (BV). These negative effects may arise from sialidase-mediated degradation of the protective mucus layer in the cervicovaginal environment. Prior biochemical studies of vaginal bacterial sialidases have focused solely on the BV-associated organism . Despite their implications for sexual and reproductive health, sialidases from other vaginal bacteria have not been characterized. Here, we show that vaginal species produce sialidases that possess variable activity toward mucin substrates. The sequences of sialidase genes and their presence are largely conserved across clades of from different geographies, hinting at their importance globally. Finally, we find that sialidase genes and transcripts, including those encoding mucin-degrading sialidases from , are highly prevalent and abundant in human vaginal genomes and transcriptomes. Together, our results identify as a critical source of sialidases in the vaginal microbiome, improving our understanding of this detrimental bacterial activity.