Comparative pangenomic analysis of predominant human vaginal lactobacilli strains towards population-specific adaptation: understanding the role in sustaining a balanced and healthy vaginal microenvironment

The vaginal microenvironment of healthy women has a predominance of Lactobacillus crispatus, L. iners, L. gasseri, and L. jensenii. The genomic repertoire of the strains of each of the species associated with the key attributes thereby regulating a healthy vaginal environment needs a substantial understanding.We studied all available human strains of the four lactobacilli across different countries, isolated from vaginal and urinal sources through phylogenetic and pangenomic approaches. The findings showed that L. iners has the highest retention of core genes, and L. crispatus has more gene gain in the evolutionary stratum. Interestingly, L. gasseri and L. jensenii demonstrated major population-specific gene-cluster gain/loss associated with bacteriocin synthesis, iron chelating, adherence, zinc and ATP binding proteins, and hydrolase activity. Gene ontology enrichment analysis revealed that L. crispatus strains showed greater enrichment of functions related to plasma membrane integrity, biosurfactant, hydrogen peroxide synthesis, and iron sequestration as an ancestral derived core function, while bacteriocin and organic acid biosynthesis are strain-specific accessory enriched functions. L. jensenii showed greater enrichment of functions related to adherence, aggregation, and exopolysaccharide synthesis. Notably, the key functionalities are heterogeneously enriched in some specific strains of L. iners and L. gasseri.This study shed light on the genomic features and their variability that provides advantageous attributes to predominant vaginal Lactobacillus species maintaining vaginal homeostasis. These findings evoke the need to consider region-specific candidate strains of Lactobacillus to formulate prophylactic measures against vaginal dysbiosis for women's health.

In vitro activity of farnesol against vaginal Lactobacillus spp

OBJECTIVE

Farnesol, a quorum-sensing molecule in Candida albicans, can affect the growth of certain microorganisms. The objective of this study was to evaluate the in vitro activity of farnesol against vaginal Lactobacillus spp., which play a crucial role in the maintenance of vaginal health.

METHODS

Growth and metabolic viability of vaginal Lactobacillus spp. incubated with different concentrations of farnesol were determined by measuring the optical density of the cultures and with the MTT assay. Morphology of the farnesol-treated cells was evaluated using a scanning electron microscope. In vitro adherence of vaginal Lactobacillus cells treated with farnesol was determined by co-incubating with vaginal epithelial cells (VECs).

RESULTS

The minimum inhibitory concentration (MIC) of farnesol for vaginal Lactobacillus spp. was 1500μM. No morphological changes were observed when the farnesol-treated Lactobacillus cells were compared with farnesol-free cells, and 100μM farnesol would reduce the adherence of vaginal Lactobacillus to VECs.

CONCLUSION

Farnesol acted as a potential antimicrobial agent, had little impact on the growth, metabolism, and cytomorphology of the vaginal Lactobacillus spp.; however, it affected their adhering capacity to VECs. The safety of farnesol as an adjuvant for antimicrobial agents during the treatment of vaginitis needs to be studied further.

[Progress in research of relationship between vaginal Lactobacillus and preterm delivery]

The vaginal flora in most healthy women is dominated by Lactobacillus species. The absence of Lactobacillus species in vaginal flora might lead to a series of symptoms, especially in pregnant women causing adverse pregnancy outcomes, such as preterm delivery. This review focuses on the progress in the research of the relationship between vaginal Lactobacillus and preterm delivery, providing reference for the reduction of the incidence of preterm delivery.