Lactobacillus biofilms and anti-Candida activity

Lactobacilli are the presiding members of the healthy human vaginal microbiota and are considered the first defense line from pathogen infection, including vulvovaginal candidiasis (VVC), whereas biofilm is the predominant microbial growth form in nature.

A study that assessed the capability of 16 vaginal Lactobacillus (L.) strains to form biofilms found that L. crispatus and L. plantarum strains exhibited the best fungistatic profile.1

The Italian study in the journal Frontiers in Microbiology also concluded that biofilms enhanced their anti-Candida (anti-C.) activity.

Lactobacilli are the presiding members of the healthy human vaginal microbiota and are considered the first defense line from pathogen infection, including vulvovaginal candidiasis (VVC), whereas biofilm is the predominant microbial growth form in nature.

The formation of biofilms inside the human body has important implications in health and disease, according to the authors, who cited that the formation of biofilm by members of the human resident microbiota is helpful because it can improve microbial persistence and influence functionality.

“Biofilm formation by members of the healthy human microbiota represents a crucial issue in the field of microbial physiology and host–microbiota interactions, beyond supporting the development of new antimycotic strategies based on probiotics grown in adherence,” wrote the authors.

The C. strains belonged to a broad collection of yeasts isolated from vaginal swabs of premenopausal, VVC-affected women during routine diagnostic procedures at the microbiology laboratory of Sant’Orsola-Malpighi University Hospital of Bologna in Italy.

The metabolome of the cultures was also assessed by 1H-nuclear magnetic resonance spectroscopy.

The 16 vaginal L. strains evaluated belong to L. crispatusL. actobacillus gasseri, L. vaginalis, and L. plantarum species.

L. plantarum strains were the best biofilm producers, while there was high variability in the level of biofilm formation among L. crispatus and L. gasseri strains.

In addition, culture supernatants derived from L. biofilm and planktonic growth were tested against a panel of Candida clinical isolates: C. albicans, C. glabrata, C. lusitaniaeC. tropicalisC. krusei, and C. parapsilosis.

L. crispatus and L. plantarum strains demonstrated the best fungistatic profile, and biofilms enhanced their anti-C. activity. But L. gasseri strains were more effective when grown in a planktonic mode.

The biofilm/planktonic mode of growth also affects L. metabolism, primarily impacting nitrogen and amino acid pathways, while anti-C. activity is strictly linked to carbohydrate metabolism

The shift from a L. planktonic culture to an adherent form indicatesnotable differences in the metabolism of nitrogen and amino acids, likely a key role of this molecule category in the formation of an adherent biomass, as has previously been proposed for L. paraplantarum.

Specifically, alanine and lysine were produced/released at higher amounts by L. in the biofilm form versus the planktonic one, whereas methionine was highly consumed by L. in biofilm growth, thus supporting previous research that the methionine pathway is connected to the biofilm formation process.

The current study underscores the interdependence between microbial mode of growth, metabolism, and functional properties.

Study results also add credence to using L. crispatus or L. gasseri as probiotics to prevent VVC or to restore vaginal eubiosis status, as well as helping to develop fourth-generation probiotics that are based on biofilm-forming strains and encapsulation techniques.

Future studies on L. biofilm formation in the vaginal niche should be designed to better understand its physiological role, according to the authors, and support the development of new antimycotic strategies based on probiotics grown in adherence.

Reference

  1. Parolin C, Croatti V, Laghi L, et al.Lactobacillus biofilms influence anti-Candida activity. Front Microbiol. Published online October 29, 2021. doi:10.3389/fmicb.2021.7503682