Production and characterization of a novel cold-active B-glucosidase and its influence on aromatic precursors of Muscat wine

B-Glucosidases (BGL)-widely used in the enological field-are enzymes that catalyze the liberation of aromatic volatiles from their glycosidic precursors during winemaking. In the present study, a BGL obtained from the Antarctic yeast Mrakia sp. LP 7.1.2016 was produced on a bioreactor scale, purified, characterized, and the enzyme's properties studied for a potential enological application. Sodium-dodecylsulfate-polyacrylamide-gel electrophoresis indicated a high molecular weight for this enzyme, it having at least two subunits of 134 and 14 kDa. BGL exhibited a pH optimum of 5.0 and retained substantial activity and stability at pH 4.0. The temper-ature range for optimal activity was 50-55 degrees C, with the enzyme demonstrating thermostability up to 50 degrees C and retaining 87% of residual activity at that temperature after 3 h. The respective kinetic constants determined with p-nitrophenyl-B-D-glucopyranoside and cellobiose were 0.38 and 1.79 mM for Km and 20.1 and 5.65 mu mol-1 mg- 1 min.1 for Vmax, B-Glucosidase manifested high activity in 10-25% (v/v) ethanol, 30.0 mg L-1 sulfur di-oxide, and 10-200 g L-1 fructose; but it was strongly inhibited by glucose, retaining only 6% of residual activity in the presence of 20 g L-1. Upon investigating the influence of the enzyme on Muscat-wine glycosidic pre-cursors, we found significant differences in terpene content after 14 days of BGL treatment at an eightfold in-crease over control-wine levels. The enzyme was more active toward the precursors of the monoterpenes nerol and geraniol and oxides of trans- and cis-linalool. These findings contribute to our understanding of the potential of cold-active enzymes in advantageous biotechnological applications to enology.

Automated summary

In this study, a B-glucosidase (BGL) obtained from Antarctic yeast Mrakia sp. LP 7.1.2016 was produced, purified, and characterized for its potential application in winemaking. The enzyme exhibited high activity and stability under optimal conditions and showed significant differences in terpene content after treatment, suggesting its potential use in enology.