Selection and identification of yeasts for the biological control of Alternaria in Malbec wine grapes

Abstract

The presence of Alternaria fungal genus, which is able to produce mycotoxin in wine grapes, could mean a health risk for wine consumers. With the aim to select a possible biological control agent in wine grapes, yeasts from the same ecosystem were evaluated. The 22.1% from total yeasts and yeast-like organisms evaluated showed antagonistic activity against Alternaria alternata in wine grape assays and most of them (14/15) showed a great antagonistic ability achieving a preventive effect. All Metschnikowia spp., Candida zemplinina and almost all Hanseniaspora uvarum evaluated strains, with higher nutritional requirements, showed antagonist capability against A. alternata. Meanwhile, none of the lesser nutritional requirement strains belonging to Aureobasidium pullulans, Cryptococcus laurenti II and Rhodotorula spp. did, suggesting a positive correlation between these factors. Molecular identification through 26S sequencing allows confirming the assigned identity by PCR-RFLP method. These findings result promising for the biological control of Alternaria in wine grapes.