Candida Tropicalis Biofilm Formation Under Secondary Bile Salt Sodium Deoxycholate

Area of Science:

• Microbiology
• Mycology
• Gastrointestinal Health

Background:

• Candida species are normal gut inhabitants exposed to bacterial metabolites like secondary bile salts.
• Secondary bile salts influence lipid absorption and microbial interactions within the intestine.

Purpose of the Study:

• To investigate the effect of sodium deoxycholate (NaDCA), a secondary bile salt, on Candida tropicalis biofilm formation.
• To compare the response of C. tropicalis to NaDCA with that of Candida albicans.

Main Methods:

• Treatment of C. tropicalis with NaDCA.
• Measurement of biofilm biomass and surface hydrophobicity.
• 3D fluorescence microscopy for biofilm structure analysis.
• RNA-sequencing (RNA-seq) to assess gene expression changes, particularly in iron metabolism.
• Analysis of virulence factor gene expression (agglutinin-like sequences, candidalysin).

Main Results:

• C. tropicalis maintained biofilm biomass and hydrophobicity in the presence of NaDCA, unlike C. albicans.
• NaDCA reduced filamentous projections in C. tropicalis biofilms.
• RNA-seq identified differential gene expression in C. tropicalis, notably in iron metabolism genes.
• Key virulence genes were less affected by NaDCA in C. tropicalis compared to C. albicans.
• High iron exposure negatively impacted C. tropicalis biofilm biomass.

Conclusions:

• NaDCA alters C. tropicalis biofilm structure and gene expression, with notable effects on iron metabolism.
• C. tropicalis exhibits a different response to NaDCA compared to C. albicans, suggesting niche differentiation.
• Secondary bile salt availability may influence the intestinal habitat preference of C. albicans and C. tropicalis.