Comparative Functional Genomics of Lactobacillus spp. Reveals Possible Mechanisms for Specialization of Vaginal Lactobacilli to Their Environment

Abstract

dLactobacilli are found in a wide variety of habitats. Four species, Lactobacillus crispatus, L. gasseri, L. iners, and L. jensenii, are common and abundant in the human vagina and absent from other habitats. These may be adapted to the vagina and possess characteristics enabling them to thrive in that environment. Furthermore, stable codominance of multiple Lactobacillus species in a single community is infrequently observed. Thus, it is possible that individual vaginal Lactobacillus species possess unique characteristics that confer to them host-specific competitive advantages. We performed comparative functional genomic analyses of representatives of 25 species of Lactobacillus, searching for habitat-specific traits in the genomes of the vaginal lactobacilli. We found that the genomes of the vaginal species were significantly smaller and had significantly lower GC content than those of the nonvaginal species. No protein families were found to be specific to the vaginal species analyzed, but some were either overor underrepresented relative to nonvaginal species. We also found that within the vaginal species, each genome coded for species-specific protein families. Our results suggest that even though the vaginal species show no general signatures of adaptation to the vaginal environment, each species has specific and perhaps unique ways of interacting with its environment, be it the host or other microbes in the community. These findings will serve as a foundation for further exploring the role of lactobacilli in the ecological dynamics of vaginal microbial communities and their ultimate impact on host health.

Identification of culturable vaginal Lactobacillus species among reproductive age women in Mysore, India

“…Research from different parts of the world shows that L. crispatus, L. gasseri and L. jensenii are the most common cultivable Lactobacillus species, and this was true in our study sample as well (Chaban et al, 2014;Mendes-Soares et al, 2014;van de Wijgert et al, 2014).…”

Black Queen evolution: the role of leakiness in structuring microbial communities

“…As with other communities with BQ functions, vitamin-dependent algae and vitamin-producing helper bacteria can coexist in culture [49]. Host-associated microbes often are auxotrophic for compounds that are available from the host, but in the case of vaginal lactobacilli many auxotrophies also appear to enforce reliance on other members of the vaginal microbiota [50]. Auxotrophy is also very common among the endosymbionts of insects, and in insects with more than one species of symbiont it is common for each symbiont to require products produced by the other [51][52][53][54][55][56].…”

The Changing Landscape of the Vaginal Microbiome

“…These inhibitory mechanisms differ among Lactobacillus species. Comparative genomic analyses of L. crispatus , L. gasseri , L. iners and L. jensenii have provided evidence that each Lactobacillus species possesses a unique repertoire of protein families and suggest these differences may reflect specific community adaptations 26,27 . Future studies aimed at characterizing the functional roles of these species-specific protein families and genes may provide important insight into how these common vaginal bacteria impact women's health.…”