Vaginal Lactobacillus gasseri biosurfactant: a novel bio- and eco-compatible anti-Candida agent

Vulvovaginal candidiasis (VVC) and recurrent vulvovaginal candidiasis (RVVC), caused by Candida spp. overgrowth, are common and challenging infections of the genital tract. Among Candida virulence factors, the ability to adhere to host epithelium and to form biofilms are frequently retrieved, especially in RVVC. Vaginal pathogen overgrowth is counteracted by resident lactobacilli, which exert a barrier thanks to the production of antimicrobial metabolites, such as biosurfactants (BS). BS was recovered from vaginal Lactobacillus gasseri BC12 and its chemical characteristics as well as its ability to lower the surface tension and to emulsify two different immiscible phases were investigated. BS showed the typical features of a lipopeptide with a critical micellar concentration of 1.2 mg/mL. BS showed antibiofilm activity towards various Candida albicans and non-albicans isolates, notably, it was able to prevent biofilm formation and eradicate preformed biofilms. The absence of cytotoxicity of BS and its ability to counteract the adhesion of Candida spp. were highlighted on HeLa cells through MTT and competition/exclusion assays, respectively. The environmental impact of BS was also investigated on a microcosm model (spring water) by culture-based and molecular (16S rRNA-targeted Illumina sequencing) methods, and no remarkable modifications in the taxonomy composition of the bacterial ecosystem were observed. To conclude, BS from L. gasseri BC12 appears as a promising, biocompatible and environmentally friendly approach to prevent and treat VVC/RVVC.