Farnesol Anti-biofilm Activity against Candida albicans Reference and Mutant Strains

Introduction: Farnesol is known as a quorum sensing (QS) molecule that has a role as an anti-biofilm agent. It is produced by C. albicans and blocks the morphological transition from yeasts to hyphae. The hyphal development is important for the formation of substantial biofilm biomass. Mutant strains lacking the filamentation genes EFG1 and TEC1 are less virulent than their reference strains.

Aims: To determine the role of the transcription factors EFG1 and TEC1 by using knockout strains (Δ/Δ efg1 and Δ/Δ tec 1) on farnesol’s mechanism of action regarding dry weight and colony count of Candida albicansbiofilms.

Study Design: tt-farnesol solutions at a concentration of 12.5 mM were prepared. Biofilms (n=6) of the strains C. albicans SN 425 (reference strain), C. albicans CJN 2330 (Δ/Δ tec1) and C. albicans CJN 2302 (Δ/Δ efg1) were treated twice daily with tt-farnesol or a vehicle control for 1 min during biofilm formation (48 h). Biofilms were also treated with 0.2% chlorhexidine (1 min) as a positive control and 0.89% NaCl (1 min) as a negative control. After treatments, biofilms were evaluated by dry weight (μg) and colony forming units per milliliters (CFU/mL).

Results: Data were analyzed by two-way ANOVA and post-hoc t-tests (α=0.05). Relative to the control, farnesol significantly reduced the CFU/mL of all the C. albicans strains and the biomass of the mutant strain CJN 2330.

Conclusion: Twice daily treatment with tt-farnesol at a concentration of 12.5 mM exhibited anti-biofilm activity against C. albicans. Analysis of strain differences suggests that the presence of the transcription factor TEC1 protects the biofilm against tt-farnesol mechanism of action.