Transport and Utilization of Glycogen Breakdown Products by spp. from the Human Vaginal Microbiome.

Multiple species frequently cooccur in vaginal microbiomes, and several factors, including competition for nutrients such as glycogen could determine their population structure. Although spp. can hydrolyze glycogen to produce glucose, maltose, maltotriose, and maltotetraose, how these sugars are transported and utilized for growth is unknown. We determined the distribution of genes encoding transporter proteins associated with the uptake of glucose, maltose, and malto-oligosaccharides and maltodextrins among species. A total of five different ABC transporters were identified in spp. of which MusEFGKI and MalXFGK were conserved across all 15 isolates. RafEFGK and TMSP (trehalose, maltose, sucrose, and palatinose) operons were specific to while the MalEFG transporter was identified in only. Although no glucose specific sugar-symporters were identified, putative "glucose/galactose porters" and components of a phosphotransferase system were identified. In laboratory experiments, all isolates grew more in the presence of glucose, maltose, maltotriose, and maltotetraose compared to unsupplemented media. In addition, most isolates (10/15) showed significantly more growth on maltotetraose compared to glucose (Kruskal Wallis,  < 0.05) suggesting their preference for longer chain malto-oligosaccharides. Our findings show that although putative MusEFGKI and MalXFGK transporters are found in all spp., some species-specific transporters are also present. Observed distribution of genes encoding transporter systems was consistent with laboratory observations that spp. grow better on longer chain malto-oligosaccharides. Increased abundance of spp. is a diagnostic characteristic of bacterial vaginosis, an imbalance in the human vaginal microbiome associated with troubling symptoms and negative reproductive health outcomes, including increased transmission of sexually transmitted infections and preterm birth. Competition for nutrients is likely an important factor in causing dramatic shifts in the vaginal microbial community. produces enzymes to digest glycogen, an important nutrient source for vaginal bacteria, but little is known about the mechanisms in for uptake of the products of this digestion, or whether use some or all of the products. Our results indicate that may have evolved to preferentially use a subset of the glycogen breakdown products, which would help them reduce direct competition with some other bacteria in the vagina.