KTCf20: a killer agent against Candida

BULACIOS G.A.; BELLOMIO A.; FERNANDEZ DE ULLIVARRI M.

Cordoba

Congreso; LII Reunión Anual de SAIB 2016; 2016

Killer yeasts are able to produce proteins or glycoproteins with antimicrobial activity known as killer toxins, and they can be used as biocontrol agents against pathogens yeasts. In this study we evaluated the biocontrol potential of killer toxins over clinical isolates of pathogenic strains of Candida spp. A set of 15 killer yeasts was used to perform a qualitative inhibition assay over lawns of 6 Candida isolates in YPD agar pH 4.5. Growth inhibition in W. anomalusCf20 cell-free supernatant (CFS, 2×104 aU/ml), was studied at different temperatures and NaCl concentrations. Heat-inactivated CFS (100 ºC, 15 min) was used as control. OD600 and cell viability were measured to calculate inhibition. Fluorescence microscopy of pathogenic strains was performed after incubation for 16 h at 20 ºC in CFS+NaCl 1% and live/dead staining using SYTO9 and PI as fluorescent probes.W. anomalus Cf20 was selected as the most active killer strain, while C. albicans 78 and C. tropicalis FBUNT3 were the most sensitive strains. CFS produced 74 and 80% inhibition of both strains, respectively, at 20 ºC and NaCl 1%. Fluorescence microscopy and viability studies revealed that CFS did not killed sensitive cells.CFS was able to highly inhibit the growth of the studied strains with fungistatic effects. Higher concentrations should be tested to evaluate if a fungicidal effect is achieved.