The killer yeast Wickerhamomyces anomalus Cf20 exerts a broad anti-Candida activity through the production of killer toxins and volatile compounds

MIGUEL FERNÁNDEZ DE ULLIVARRI; GABRIELA A. BULACIOS; SILVIA A. NAVARRO; LUCÍA LANZA; LUCIA M. MENDOZA; MIRIAM C. CHALÓN

MEDICAL MYCOLOGY

TAYLOR & FRANCIS LTD

Lugar: Londres; Año: 2020 p. 1 - 12

1369-3786

Candidiasis is a group of opportunistic infections caused by yeast of the genus Candida. The appearanceof drug resistance and the adverse effects of current antifungal therapies require the search for new, moreefficient therapeutic alternatives. Killer yeasts have aroused as suitable candidates for mining new antifungal compounds. Killer strains secrete antimicrobial proteins named killer toxins, with promissory antifungalactivity. Here we found that the killer yeast Wickerhamomyces anomalus Cf20 and its cell-free supernatant(CFS) inhibited six pathogenic strains and one collection strain of Candida spp. The inhibition is mainly mediated by secreted killer toxins and, to a lesser extent, by volatile compounds such as acetic acid and ethylacetate. A new large killer toxin (>180 kDa) was purified, which exerted 70?74% of the total CFS anti-Candidaactivity, and the previously described glucanase KTCf20 was inhibitory in a lesser extent as well. In addition,we demonstrated that Cf20 possesses the genes encoding for the β-1,3-glucanases WaExg1 and WaExg2,proteins with extensively studied antifungal activity, particularly WaExg2. Finally, the 10-fold concentratedCFS exerted a high candidacidal effect at 37°C, completely inhibiting the fungal growth, although the nonconcentrated CFS (RCF 1) had very limited fungistatic activity at this temperature. In conclusion, W. anomalusCf20 produces different low and high molecular weight compounds with anti-Candida activity that could beused to design new therapies for candidiasis and as a source for novel antimicrobial compounds as well.