Effect of fatty acids on biofilm formation, oxidative stress and antifungal susceptibility of Candida albicans and Candida dubliniensis
Thibane, Vuyisile Samuel
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Candida albicans and C. dubliniensis are commensals of the gastrointestinal and genitourinary tract in healthy individuals. However, in diseased individuals they can cause superficial infections to deep seated mycoses. Both species form mycelial networks called biofilms, and formation of biofilms results in increased resistance towards antifungal compounds currently in use. Therefore, there is a need for alternative antifungal compounds such as fatty acids. Research has shown that supplementation of growth medium with polyunsaturated fatty acids (PUFAs), increased the unsaturation index and made cells susceptible to lipid peroxidation and cell death. During this study this phenomenon was evaluated on biofilms of C. albicans and C. dubliniensis using selected PUFAs. Due to differences in the carbon chain length and saturation of fatty acids, they interact differently with the cell membrane and will have different peroxidisability values. The results from the study showed C18:4 n-3 and C20:5 n-3 were taken in by the cell and resulted in increased unsaturation index. The results further indicated oxidative stress-induced apoptosis following supplementation with C18:4 n-3 and C20:5 n-3 in biofilms of both C. albicans and C. dubliniensis. The induction of apoptosis following supplementation by C18:4 n-3 and C20:5 n-3 was confirmed by mitochondrial membrane potential assay, Annexin V-FITC staining, TUNEL assay and DAPI staining. The use of C18:4 n-3 in synergism with amphotericin B resulted in decreased dosage of the antifungal compound needed to inhibit biofilms of C. albicans and C. dubliniensis.