Characterization of a Lactobacillus gasseri strain as a probiotic for female vaginitis

Vaginitis, a prevalent gynecological condition in women, is mainly caused by an imbalance in the vaginal micro-ecology. The two most common types of vaginitis are vaginal bacteriosis and vulvovaginal candidiasis, triggered by the virulent Gardnerella vaginalis and Candida albicans, respectively. In this study, a strain capable of inhibiting G. vaginalis and C. albicans was screened from vaginal secretions and identified as Lactobacillus gasseri based on 16S rRNA sequences. The strain, named L. gasseri VHProbi E09, could inhibit the growth of G. vaginalis and C. albicans under co-culture conditions by 99.07% ± 0.26% and 99.95% ± 0.01%, respectively. In addition, it could significantly inhibit the adhesion of these pathogens to vaginal epithelial cells. The strain further showed the ability to inhibit the enteropathogenic bacteria Escherichia coli and Salmonella enteritidis, to tolerate artificial gastric and intestinal fluids and to adhere to intestinal Caco-2 cells. These results suggest that L. gasseri VHProbi E09 holds promise for clinical trials and animal studies whether administered orally or directly into the vagina. Whole-genome analysis also revealed a genome consisting of 1752 genes for L. gasseri VHProbi E09, with subsequent analyses identifying seven genes related to adhesion and three genes related to bacteriocins. These adhesion- and bacteriocin-related genes provide a theoretical basis for understanding the mechanism of bacterial inhibition of the strain. The research conducted in this study suggests that L. gasseri VHProbi E09 may be considered as a potential probiotic, and further research can delve deeper into its efficacy as an agent which can restore a healthy vaginal ecosystem.