Cytotoxic effects of the killer toxin KTCf20 against Candida spp.

FERNÁNDEZ DE ULLIVARRI M; BULACIOS GA; BELLOMIO A

CABA

Congreso; Reunión Conjunta de Sociedades de Biociencias; 2017

SAIB SAB

Killer yeasts are able to produce proteins or glycoproteins withantimicrobial activity known as killer toxins, and they can be usedas biocontrol agents against pathogens yeasts. In previous studies,we demonstrated the glucanase activity of the killer toxin KTCf20,produced by Wickerhamomyces anomalus Cf20. In this study, weevaluated the cytotoxic effects of KTCf20, present in cell-free su-pernatant (CFS), over two clinical isolates of pathogenic strains ofCandida spp.Growth inhibition of C. albicans and C. tropicalis in W. anomalusCf20 CFS (2×10 4 aU/ml), was studied at different temperatures (20and 30 oC) and NaCl concentrations (0 and 1%). OD600 and cellviability were measured to calculate inhibition. Fluorescence micros-copy (FM) of pathogenic strains was performed after incubation for 2h at 20 oC in CFS+NaCl 1% and live/dead staining using SYTO9 andPI as fluorescent probes. Transmission electron microscopy (TEM)was also performed to evaluate the cytotoxic effects of CFS on Can-dida cells. In every experiment, heat-inactivated CFS (100 oC, 15min) was used as control.CFS produced a growth inhibition of 74 and 80%, and 1-2 log cfu/ml on C. albicans and C. tropicalis, respectively, at 20 oC and NaCl1%. Its inhibitory activity decreased at 30 oC. Fluorescence micros-copy, TEM and viability results showed that CFS has a fungistaticand fungicidal effect at a 2-h treatment on C. albicans 78 and C.tropicalis FBUNT3, respectively.CFS was able to inhibit the growth of C. albicans and C. tropica-lis with fungistatic and fungicidal effects, respectively. These effectscould be explained by the different cell wall thickness of both strains.