This study characterised the diversity of filamentous fungi and yeasts during Malbec grape fermentation in the Southern Oasis of Mendoza (Argentina) winegrowing region, under different sanitary conditions and SO2 treatments, using morphological and ITS-RFLP-based molecular methods. Alternaria, Cladosporium and Penicillium were present in both sound and damaged grapes, while Aspergillus and Botrytis were primarily found in damaged grapes. The predominant yeast species in both sound and damaged grape must, at lower and higher maturity levels, were Aureobasidium pullulans and Hanseniaspora spp. At higher grape ripening levels species diversity increased, with Hanseniaspora vineae, Metschnikowia pulcherrima and Candida membranifaciens dominating, and others such as Pichia kudriavzevii and Issatchenkia terricola appearing. A. pullulans and M. pulcherrima were highly tolerant to SO2. Notably, the species Meyerozyma guilliermondii, Zygoascus hellenicus and Hanseniaspora uvarum were exclusively present in damaged grape must, while Zygosaccharomyces bailii was also found in sound grape must. Hanseniaspora spp. and P. kudriavzevii predominated at mid-fermentation and persisted at the end of the process, highlighting their resistance to wine conditions and their potential to influence post-fermentative dynamics. These findings emphasise the significant influence of grape sanitary status on mycobiota composition, with important implications for fermentation behaviour and final wine quality.
Garau et al. (Fri,) studied this question.