Abstract:
Yeast biofilms pose health risks in clinical environments and food industry. Despite years of effort, new antifungal approaches are needed since it is known that biofilms show much greater resistance to the antifungal agents than their free-living counterparts. Hence, we investigated antifungal activity of plant extracts such as Humulus lupulus, Alpinia katsumadai and Evodia rutaecarpa against Candida albicans ATCC 10261, Candida glabrata ZIM 2369 and Pichia membranifaciens ZIM 2417. The aim of this study was to investigate whether these plant extracts can interfere with biofilm formation as well as acting on preformed biofilms. The minimal inhibitory concentrations (MICs) of plant extracts were determined using the CLSI M27-A2 broth microdilution method. The method used to assess antibiofilm activity was crystal violet staining. According to the MIC values in this study, all plant extracts were effective in the inhibition of yeast strains. On the other hand, A. katsumadai, E. rutaecarpa and H. lupulus extracts exhibited the highest antibiofilm activity against C. albicans to the stainless steel surface at both tested concentrations (1/2 × MIC and 1 × MIC). A. katsumadai was also effective in the initial phase of biofilm formation of C. glabrata at 1/2 × MIC and 1 × MIC, while the inhibition of preformed biofilm was more difficult to achieve. Our results clearly demonstrate that biofilms of C. glabrata are more resistance to the extracts as compared to C. albicans. Regarding P. membranifaciens, extracts of A. katsumadai and E. rutaecarpa were promoted the growth and development of a preformed biofilm.
