The combinational inhibitory effects of Lactobacillus, 1-monoglycerides, and grapefruit seed extract against Gardnerella vaginalis KCTC 5097

Abstract

The objective of this study was to observe the antibacterial effects of lactobacilli, 1-monoglycerides (MGs) and grapefruit seed extract (GSE) against the vaginosis-associated pathogen Gardnerella vaginalis. Five lactobacilli were selected from 26 lactobacilli by observing the effect of pH (pH=7) adjusted lactobacilli cell-free culture supernatant (CFCS) on the viability of G. vaginalis. Among them, 3 strains of Lactobacillus showed relatively high inhibition on the growth of G. vaginalis KCTC 5097 during the co-culture of Lactobacillus and G. vaginalis. In addition, the effects of MGs and GSE on the bacterial growth curve were monitored at various levels. Glycerol monolaurate (GML) and GSE had MIC (minimum inhibitory concentration) values of 78.125 ug/mL and 20 ppm, respectively, against G. vaginalis at which the growth of the selected 3 Lactobacillus strains was inhibited to a much lesser degree. In the co-culture assay of Lactobacillus and G. vaginalis in the presence of GML and GSE, the growth of G. vaginalis was considerably suppressed whereas that of Lactobacillus was minimally affected. Taken together, the selected Lactobacillus, GML and GSE could be potential therapeutic candidates to suppress the colonization of G. vaginalis in the vaginal niche.