Bacterial amylases enable glycogen degradation by the vaginal microbiome.

The human vaginal microbiota is frequently dominated by lactobacilli and transition to a more diverse community of anaerobic microbes is associated with health risks. Glycogen released by lysed epithelial cells is believed to be an important nutrient source in the vagina. However, the mechanism by which vaginal bacteria metabolize glycogen is unclear, with evidence implicating both bacterial and human enzymes. Here we biochemically characterize six glycogen-degrading enzymes (GDEs), all of which are pullanases (PulA homologues), from vaginal bacteria that support the growth of amylase-deficient Lactobacillus crispatus on glycogen. We reveal variations in their pH tolerance, substrate preferences, breakdown products and susceptibility to inhibition. Analysis of vaginal microbiome datasets shows that these enzymes are expressed in all community state types. Finally, we confirm the presence and activity of bacterial and human GDEs in cervicovaginal fluid. This work establishes that bacterial GDEs can participate in the breakdown of glycogen, providing insight into metabolism that may shape the vaginal microbiota.

Complete Genome Sequences of 37 Bacteria from the Human Vaginal Tract.

Microorganisms colonizing the human vaginal mucosa are associated with healthy states, as well as conditions such as bacterial vaginosis and infection-associated preterm birth. Here, we report complete genome sequences of 37 bacterial isolates from the human vaginal tract.