Biocontrol ability and action mechanism of food-isolated yeast strains against Botrytis cinerea causing post-harvest bunch rot of table grape

Strains belonging to the species Saccharomyces cerevisiae, Wickerhamomyces anomalus, Metschnikowiapulcherrima and Aureobasidium pullulans, isolated from different food sources, were tested in vitro asbiocontrol agents (BCAs) against the post-harvest pathogenic mold Botrytis cinerea. All yeast strainsdemonstrated antifungal activity at different levels depending on species and medium. Killer strains ofW. anomalus and S. cerevisiae showed the highest biocontrol in vitro activity, as demonstrated by largestinhibition halos. The competition for iron and the ability to form biofilm and to colonize fruit woundswere hypothesized as the main action mechanisms for M. pulcherrima. The production of hydrolyticenzymes and the ability to colonize the wounds were the most important mechanisms for biocontrolactivity in A. pullulans and W. anomalus, which also showed high ability to form biofilm. The productionof volatile organic compounds (VOCs) with in vitro and in vivo inhibitory effect on pathogen growth wasobserved for the species W. anomalus, S. cerevisiae and M. pulcherrima. Our study clearly indicates thatmultiple modes of action may explain as M. pulcherrima provide excellent control of postharvest botrytisbunch rot of grape.