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

Microb Cell. 2023 Mar 21;10(4):88-102. doi: 10.15698/mic2023.04.795. eCollection 2023 Apr 3.

Abstract

The exploration of the interference prompted by commensal bacteria over fungal pathogens is an interesting alternative to develop new therapies. In this work we scrutinized how the presence of the poorly studied vaginal 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 planktonic 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 counteracted the acidification prompted by L. gasseri thus impacting the balance between 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 therapies based on probiotics, in particular, those based on vaginal lactobacilli species, helping to reduce the significant burden that infections caused by Candida have today in human health.

Keywords: candida physiology; lactobacilii-Candida interference; lactobacillus gasseri; probiotics; vaginal candidiasis; vaginal lactobacilii.

Grants and funding

This study was supported by funds received from FCT - Fundação para a Ciência e a Tecnologia, I.P., in the scope of the project LactoCan (PTDC/BIA-MIC/31515/2017); the project supporting the Research Unit Institute for Bioengineering and Biosciences (UIDB/04565/2020) and the project supporting Institute for Health and Bioeconomy, i4HB (LA/P/0140/2020). FCT is also acknowledged for funding a PhD grant (PD/BD/143026/2018) to NAP through the doctoral program DP_AEM.