Abstract: Objective To investigate inhibitory effect of chitosan on Candida albicans biofilm, and to discuss the possible mechanism.Methods XTT reduction assay was used to investigate the influence of different concentrations of chitosan on Candiia albicans biofilm formation and cell adherence.Microscopic examination was conducted to assess the effect of chitosan on morphogenesis of Candida albicans biofilm.The mRNA expressions of CDC35,PDE2,EFG1 and HWP1 were measured by realtime RT-PCR with different concentrations of chitosan.Results The inhibition rates of chitosan against Candida albicans biofilm formation were (19.6±1.2)% by 0.02 mg/mL and (96.96±0.6)% by 0.32 mg/mL.Chitosan (0.16 mg/mL) inhibited different stages of biofilm,with (78.6±0.5)%,(54.4±0.9)% and (41.1±1.1)% inhibition rates when cells was treated for 0 h,12 h and 48 h,respectively.Chitosan from 0.02 mg/mL to 0.32 mg/mL showed distinct inhibitive effect on adhesion to Candida albicans cultured for 30 min,60 min,90 min and 120 min (P<0.05).The mRNA expression levels of CDC35,EFG1 and HWP1 were decreased in Chitosan treated cells, while the PDE mRNA level was increased.Conclusion Chitosan may inhibit the Candida albicans biofilm formation through regulating Ras signaling pathway and cell adherence.

Key words: Chitosan, Candida albicans, biofilm, Ras signaling pathway