Study Of β-glycosidase Activity In Wine Lactic Acid Bacteria

Wine lactic acid bacteria play an important role in winemaking by undertakingmalolactic fermentation （MLF）, but little domestic information was available on theirβ-glycosidase properties. β-glycosidase could liberate wine aroma through hydrolysis ofaroma precursors in the β-glycosidic form, and thus increase intensity and complexity of winearoma.This study investigated β-glycosidase activity in51strains of lactic acid bacteria, and theresponses of β-glycosidase activity to wine related single-factors and model wineenvironment in the selected10Oenococcus oeni strains and10non-Oenococcus oeni strains（Lactobacillus, Leuconostoc and Pediococcus） respectively. The results showed that all testedstains possessed varying degrees of β-glycosidase activities. Two strains, namely CS-1b（Oenococcus oeni） and Lb-2（Lactobacillus brevis）, exhibited high enzymatic activity amongthe tested strains affected by wine related inhibitors. The conclusions are as follows,1. The tested commercial strains of Oenococcus oeni, namely OENO2and VD,possessed low β-glycosidase activity, which were strongly inhibited by wine environment.2. The enzymatic properties of wine lactic acid bacteria were described as follows:Strains possessed comparative high β-glycosidase activity in pH3.8⁵.8（for Oenococcus oeni）and pH3.8⁷.0（for non-Oenococcus oeni）; the optimum temperature were30～39.3℃; theenzymatic activity was slightly influenced by low concentration of sugar, however, enzymaticactivity of most strains was significantly inhibited by high sugar content; alcohol inducedserious decrease of β-glycosidase activity in all strains, and the tested strains exhibited almostno enzymatic activity in ethanol content of14%（V/V）; in model wine, the tested strainsmaintained13.63³4.55%of the highest enzymatic activity of each strain.3. According to research on Oenococcus oeni, strain CS-1b exhibited optimumenzymatic properties among the tested strains. Its enzymatic properties were as follows:optimal conditions were pH5.0,30℃, and it retained high β-glycosidase activity under bothwine pH and wine temperature; its activity was slightly activated by low concentration ofglucose and fructose separately, while it could be slightly inactivated by high concentration ofglucose and fructose individually; high ethanol content could strongly inhibit its activity; in model wine, CS-1b exhibited an activity of3.755μmol g^-1min^-1,34.55%of its highestenzyme activity.4. Based on research conducted on non-Oenococcus oeni, strain Lb-2possessedoptimum enzymatic properties among the tested strains, with its enzymatic properties shownas follows: optimum pH and temperature were pH4.2and30℃respectively, and it possessedhigh β-glycosidase activity at typical wine pH, wine temperature and low concentration ofsugar; but it was strongly inhibited by high ethanol content; in model wine, the enzymaticactivity of Lb-2was3.288μmol g^-1min^-1,34.04%of its highest enzyme activity.