Acetate modulates the inhibitory effect of Lactobacillus gasseri against the pathogenic yeasts Candida albicans and Candida glabrata

Abstract

The exploration of the interference prompted by commensal bac-teria over fungal pathogens is an interesting alternative to develop new ther-apies. In this work we scrutinized how the presence of the poorly studied vag-inal species Lactobacillus gasseri affects relevant pathophysiological traits of Candida albicans and Candida glabrata. L. gasseri was found to form mixed biofilms with C. albicans and C. glabrata resulting in pronounced death of the yeast cells, while bacterial viability was not affected. Reduced viability of the two yeasts was also observed upon co-cultivation with L. gasseri under plank-tonic conditions. Either in planktonic cultures or in biofilms, the anti-Candida effect of L. gasseri was augmented by acetate in a concentration-dependent manner. During planktonic co-cultivation the two Candida species counter-acted the acidification prompted by L. gasseri thus impacting the balance be-tween dissociated and undissociated organic acids. This feature couldn’t be phenocopied in single-cultures of L. gasseri resulting in a broth enriched in acetic acid, while in the co-culture the non-toxic acetate prevailed. Altogether the results herein described advance the design of new anti-Candida thera-pies based on probiotics, in particular, those based on vaginal lactobacilli spe-cies, helping to reduce the significant burden that infections caused by Can-dida have today in human health.

Keywords

• lactobacilii-candida interference
• vaginal lactobacilii
• vaginal candidiasis
• probiotics
• lactobacillus gasseri
• candida physiology