Essential oils as antifungal and anti-adhesion agents against Candida albicans and Saccharomyces cerevisiae

Abstract

Multiple drug resistance of food spoilage and human pathogenic microorganisms has been developed in recent years due to inadequate and non-selective use of synthetic antimicrobial agents commonly used in the treatment of infectious diseases and food preservation. The use of natural antimicrobial agents has gained much attention to extend shelf-life, increase the safety of food products in the food industry and inhibit disease-causing microorganisms. The aim of this study was to evaluate antifungal and anti-adhesion activity of fifteen essential oils (EOs) and their compounds against yeast Candida albicans ATCC 10231and Saccharomyces cerevisiae ATCC 9763. Antifungal activity was determined by testing the minimum inhibitory concentration (MIC) and the minimum fungicidal concentration (MFC) of essential oils and compounds. The essential oils of Cinnamonum zeylanieum and Eugenia caryophyllus showed the highest antifungal activity with MICs ranging from 0.078 to 1.25 mg/mL and 0.039 to 0.078 mg/mL, respectively. On the other hand, essential oils of Rosmarinus officinalis and Salvia officinalis had significantly weaker antifungal properties than the other EOs. MIC concentrations were used to assess the inhibition of adhesion of the tested yeasts in a microtiter plate using the crystal violet staining method. Based on the percentage of adhesion inhibition, yeast S. cerevisiae showed a high level of resistance to antifungal agents. Among the essential oils examined, E. cariyophyllus had the strongest effect with a percentage of inhibition up to 63.5%. The most active anti-adhesion compounds tested were carvacrol and thymol. Considering the role of biofilm in food spoilage and clinical diseases, inhibition of the initial phase of biofilm formation by natural antimicrobial agents may be an alternative to commonly used synthetic ones.