β-(1 → 3)-Glucanolytic Yeasts from Brazilian Grape Microbiota: Production and Characterization of β-Glucanolytic Enzymes by Aureobasidium pullulans 1WA1 Cultivated on Fungal Mycelium

A total of 95 yeast strains were isolated from the microbiota of different grapes collected at vineyards in southern Brazil. The yeasts were screened for beta-(1 -> 3)-glucanases using a newly developed zymogram method that relies upon the appearance of clearance zones around growing colonies cultured on agar-botryosphaeran medium and also by submerged fermentation on nutrient medium containing botryosphaeran, a (1 -> 3),(1 -> 6)-beta-d-glucan. Among 14 beta-(1 -> 3)-glucanase-positive yeasts identified, four strains produced the highest beta-glucanolytic activities and were evaluated for enzyme production on cellobiose, botryosphaeran, and mycelial biomass from Botryosphaeria rhodina (MAMB-05). Yeast strain 1WA1 produced the highest beta-(1 -> 3)-glucanase and beta-glucosidase activities and was identified by molecular characterization as Aureobasidium pullulans. The physicochemical properties of the crude beta-glucanolytic enzyme preparation were characterized, and the preparation was used to hydrolyze several beta-d-glucans (laminarin, botryosphaeran, lasiodiplodan, pustulan, and curdlan). The production and physicochemical properties of the beta-glucanolytic preparation enable its potential applications in wine enology and production of prebiotics through hydrolysis of beta-d-glucans.