Efficacy of antagonistic yeasts in reducing grey mould of grapes and bioprotection activity in winemaking

Biocontrol agents (BCAs) offer a sustainable alternative to synthetic fungicides for disease management. This study evaluated the efficacy of antagonistic yeasts in controlling grey mould (Botrytis cinerea) on Nebbiolo grapes postharvest and assessed their impact on the fruit microbiome and wine quality by targeting Hanseniaspora uvarum. Over two years, grape bunches inoculated with B. cinerea were treated with Aureobasidium pullulans, Metschnikowia pulcherrima, Pichia kluyveri, Starmerella bacillaris, and Torulaspora delbrueckii. All treatments significantly reduced rot incidence at seven and 14 days post-inoculation, with M. pulcherrima and T. delbrueckii being most effective. Microbiome analysis revealed a reduction in Botrytis spp. and modifications in other fungal genera. Treatments also reduced H. uvarum populations on grapes and during alcoholic fermentation, with S. bacillaris and T. delbrueckii achieving a complete reduction after four days in spontaneous fermentations. Importantly, Saccharomyces cerevisiae populations were unaffected. These findings highlight the potential of yeast BCAs in managing grey mould and improving wine quality.