Microbial competition between Escherichia coli and Candida albicans reveals a soluble fungicidal factor

Area of Science:

• Microbiology
• Mycology
• Human Microbiome

Background:

• Candida albicans causes severe infections, mainly in vulnerable populations, despite widespread asymptomatic colonization.
• The human microbiota and immune system are believed to prevent C. albicans overgrowth.
• Understanding protective microbial interactions is crucial for managing fungal infections.

Purpose of the Study:

• To investigate the in vitro interaction between Escherichia coli and Candida albicans.
• To identify mechanisms by which E. coli may inhibit C. albicans growth.
• To explore the role of specific nutrients in mediating this interaction.

Main Methods:

• In vitro co-culture experiments comparing E. coli (strain MG1655) and C. albicans (strain SC5314).
• Analysis of cell-free supernatants from E. coli cultures for inhibitory activity against C. albicans.
• Investigation of the role of magnesium concentration in the observed toxicity.

Main Results:

• Escherichia coli was found to outcompete and kill Candida albicans in vitro.
• E. coli produces a soluble factor with antifungal activity against C. albicans.
• The antifungal activity of this soluble factor is dependent on magnesium concentration, with depletion being essential for toxicity.

Conclusions:

• Escherichia coli possesses a mechanism to inhibit and kill Candida albicans in vitro.
• Magnesium depletion is a key factor in the toxicity of an E. coli-secreted soluble factor against C. albicans.
• This study highlights a specific microbial interaction with potential implications for controlling C. albicans infections.