Biofilm formation of Candida albicans: responders vs non-responders to farnesol

S. Desmeules, J. Séguin and J. Barbeau.

The opportunistic dimorphic yeast Candida albicans is frequently encountered in oral infections such as denture-related stomatitis, where it is associated with oral biofilms. Studies on C. albicans biofilms show that the hypha1/mycelial form takes part in biofilm development. The isoprenoid farnesol is involved in the regulation of morphological transition in C. albicans. We demonstrated that some clinical strains do not respond to farnesol-induced morphological transition. We tested the hypothesis that farnesol would inhibit the ability of the yeast to organize into a biofilm and that strains that do not respond to farnesol would form more thicker biofilms. Six clinical C. albicans strains, including two farnesol non-responders, were grown either in 50% serum, R2A and TYE media. Biofilms were monitored by microscopic observation and crystal violet staining. Biofilm formation was completely inhibited by 300 I.LM farnesol, a significant reduction was obtained with 30 I.LM while 3 I.LM had little influence. A reduction of 100 %, 10% to 70% and and less than 10% respectively was observed. Biofilm formation by farnesol non-responders was not hindered by exogenous farnesol but they responded to carbohydrates by forming thicker biofilms. The production of farnesol by C. albicans may influence biofilm formation in vivo and thus modulate the colonization process.