NATIVE YEAST FROM DISTINCT ORGANS OF GRAPEVINES ESTABLISHED IN QUERETARO, MEXICO, AND THEIR POTENTIAL OENOLOGICAL UTILIZATION

The aim of this study was to isolate, identify and determine the oenological potential of yeasts present in Vitis vinifera organs of grapevines established in Queretaro State, Mexico. The yeast distribution was influenced by the organ and the sampling season, and the yeast populations ranged from 0.8 and 5.5 Log CFU/g. A total of 93 yeasts were isolated, identified by RFLP and confirmed by sequencing of the ITS region, prevailing Aureobasidium cf. melanogenum and Basidiomycota yeast. The identified species with previously reported oenological potential were: Pichia cf. kluyveri and Clavispora cfopuntiae. Remarkably, P. cf. kluyveri 3.1HM showed killer phenotype and was the most tolerant to sulfur dioxide, and survived 72 h after its inoculation in 'Tempranillo' must. C. cf. opuntiae 5.7HM showed beta-glucosidase activity, the highest tolerance to 5 % ethanol and 25 degrees Brix (sugar levels). On the contrary, Rhodotorula isolates were not tolerant to stress conditions, and R. mucilaginosa 8HM did not grow under must conditions. Mixed fermentation using H. uvarum NB108/S. cerevisiae N05 resulted in the highest volatile acidity (0.45 g/L acetic acid), while no differences for total acidity, alcohol strength, residual sugars and total SO2 were found between the mixed fermentations treatments. This study provides an insight into the yeast diversity present in grapevines established in Queretaro, Mexico, and the oenological potential of. P. cf. kluyveri 3.1HM.