The characterisation of a novel Pichia anomala β-glucosidase with potentially aroma-enhancing capabilities in wine

The production and characterisation of beta-glucosidase from an isolated yeast strain classified as a Pichia anomala MDD24 were studied. The result shows that cellobiose is a good inducer for extracellular beta-glucosidase production and optimum concentration is 1.5 percent cellobiose in yeast peptone dextrose medium. The purified beta-glucosidase from Pichia anomala MDD24 exhibited a specific activity of 614 +/- 14 U mg(-1) of protein and a molecular mass of 42 kDa. This enzyme was slightly inhibited by fructose and sucrose in the range of 4 to 20% (w/v). An ethanol concentration between 4 and 20% (v/v) activated P-glucosidase activity, at presence 16% (v/v) ethanol, beta-glucosidases obtained maximum relative activity around 150%. The optimum pH and optimum temperature for a-glucosidase activity were 4.5 and 40 degrees C, respectively. Although the activity under the pH and temperature of wine production (pH 3.5-4.0 and 15-20 degrees C) was quite low, the enzyme was stable and the relative activities were higher than commercial enzyme under those conditions. The extracellular beta-glucosidase from Pichia anomala MDD24 makes it possible to release glucosidically-bound monoterpenes, which are the major contributors to floral and fruity aromas in wines from Muscat-type varieties, at final stage of alcoholic fermentation.