Isolation and Properties of β-Glucosidase Produced by Debaryomyces hansenii and Its Application in Winemaking

An intracellular β-glucosidase (EC 3.2.1.21) from Debaryomyces hansenii Y-44 was purified and characterized. The enzyme was purified to homogeneity from the cell-free extracts by a combination of column chromatography with DEAE-Toyopearl 650M and Butyl-Toyopearl 650S. The size of the enzyme was 95 kDa by native-PAGE, and the pl was 4.9. The enzyme was the most active at pH 7.0 and at around 25°C. The activity was highly tolerant to glucose, and only 20% inhibited in 500 m M glucose. The enzyme was tolerant to ethanol; its activity was only slightly reduced by 6% in the presence of 15% (v/v) ethanol. As the enzyme was inhibited with p -chloromercuribenzoate, it belongs to the class of SH-enzymes. The enzyme efficiently released monoterpenols from the glycosides extracted from Muscat grape must. The fermentation of Muscat juice coupled with the enzyme addition produced a considerable increase in the concentration of monoterpenols. Especially the linalool and nerol contents increased by 90% and 116%, respectively. The practical usefulness of the enzyme in juice processing and winemaking was suggested.