# Diet-responsive genetic determinants of intestinal colonization in the yeast Candida albicans

## TL;DR

This study shows that a diet rich in long-chain fatty acids like oleic acid enhances the ability of the yeast Candida albicans to colonize the gut, partly by altering its cell surface.

## Contribution

The study identifies a diet-induced mechanism in Candida albicans that promotes gut colonization through cell surface remodeling, independent of fatty acid metabolism.

## Key findings

- Mice fed a high oleic acid diet showed increased Candida albicans colonization and fecal fungal load.
- The SOK1 kinase was identified as a key regulator of cell wall mannan exposure and mucin binding in response to oleic acid.
- Oleic acid induces transcription factors that enhance intestinal colonization via cell surface remodeling in low-oxygen environments.

## Abstract

Dietary components influence microbial composition in the digestive tract. Although often viewed as energy sources, dietary components are likely to shape microbial determinants of intestinal colonization beyond metabolism. Here, we report that a dietary long-chain fatty acid enhances the yeast Candida albicans colonization of the murine gut partly by eliciting modifications to the fungal cell surface. Mice fed an oleic acid-rich diet were readily colonized by C. albicans and exhibited higher fungal load in feces compared with rodents fed an isocaloric control diet. Surprisingly, β-oxidation, a catabolic process to break down fatty acids for energy production, was dispensable for C. albicans to colonize the high oleic acid diet-fed mice. 16S rRNA analysis detected rather modest differences in the bacterial communities between control and oleic acid-rich diets. We identified SOK1 as an oleic acid-induced kinase that dictates cell wall mannan exposure and binding to intestinal mucin under anaerobic conditions. Furthermore, oleic acid induced the expression of several C. albicans transcription factors that positively regulate intestinal colonization via remodeling of the fungal cell surface. We posit that in environments largely devoid of oxygen like the large intestine, dietary oleic acid favors a C. albicans cell surface configuration that enhances gut occupation.

Candida albicans is a fungal pathobiont that inhabits the digestive tract of most human adults. The fungus has roles in health and disease because it modulates prominent immune-inflammatory host responses from the gut, and in individuals with debilitated defenses, it can disseminate from the gastrointestinal tract, producing life-threatening infections. Here, we investigate how a dietary component shapes C. albicans physiology and ultimately its ability to inhabit the mammalian gut.