Abstract: Objective To investigate the inhibitory effect of farnesol on mixed biofilm of Candida albicans and Enterococcus faecalis. Methods The mixed biofilms of Candida albicans and Enterococcus faecalis were formed on flat-bottom 96-well microtiter plates and two study groups(24 and 48 Group) were noted, than respectively incubated in the RPMI 1640 with different concentration of farnesol (100-800μmol/L) for 24 hours. The XTT reduction assay was employed to evaluate the inhibitory effect of farnesol to the mixed biofilms. Biofilms morphology was observed by inverted microscope. The antibacterial effect of farnesol on the mixed biofilm of Candida albicans and Enterococcus faecalis was observed under confocal laser scanning microscope. Results Farnesol (100-800μmol/L) has inhibitory effect on mixed biofilm of Candida albicans and Enterococcus faecalis, and the inhibitory effect increased with the increase of farnesol concentration. The sessile minimum inhibitory concentration 50% (SMIC50，sessile minimum inhibitory concentration 50%) of farnesol was 150μmol/L for 24 hours and 200μmol/L for 48 hours. Conclusion Farnesol can inhibit the growth of mixed biofilm of Candida albicans and Enterococcus faecalis. The inhibitory potency of farnesol was related to its concentration and the phase of biofilms, and high concentration of farnesol was more effective than that of low concentration .

Key words: Farnesol, Candida albicans, XTT reduction assay, Confocal Laser Scanning Microscope