Identification and Partial Characterization of Glycosidic Activities of Commercial Strains of the Lactic Acid Bacterium,Oenococcus oeni

Abstract

β-glucosidase activity was measured in cultures derived from 11 commercial preparations of <i>Oenococcus oeni</i>, which are utilized for the malolactic fermentation of wine. All cultures produced a detectable activity seen as the hydrolysis of <i>p</i>-nitrophenyl-β-D-glucopyranoside. Detectable activities against <i>p</i>-nitrophenyl-β-D-xylopyranoside and, to a lesser extent for selected isolates, <i>p</i>-nitrophenyl-α-L-arabinopyranoside, were also observed. The activity occurred in both the supernatant and cell-associated fractions, with the combined total activity and its relative distribution varying according to strain and growth stage. In evaluating the potential of these activities as liberators of glyco-conjugated grape aromas, responses to enological pH values, glucose/ fructose and ethanol concentrations were determined. Over the pH range of 3.5 to 4.0, 12% to 43% of the activity observed at the optimal pH of 5.5 was retained. Depending on the isolate examined, the presence of up to 166 m<i>M</i> sugar yielded responses ranging between 30% enhancement and 93% inhibition. Similarly, responses to ethanol ranged from 80% enhancement to 73% inhibition. When examined in a combinatorial manner, a heightened inhibition by some pH/sugar/ethanol combinations indicated a synergism for some variables. The potential enological significance of these findings is discussed.