Identification and partial characterization of glycosidic activities of commercial strains of the lactic acid bacterium, Oenococcus oeni

R-glucosidase activity was measured in cultures derived from 11 commercial preparations of Oenococcus oeni, which are utilized for the malolactic ferm entation of wine. Ail cultures produced a detectable activity seen as the h ydrolysis of p-nitrophenyl-beta -D-glucopyranoside. Detectable activities a gainst p-nitrophenyl-beta -D-xylopyranoside and, to a lesser extent for sel ected isolates, p-nitrophenyl-alpha -L-arabinopyranoside, were also observe d. The activity occurred in both the supernatant and cell-associated fracti ons, 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 en ological pH values, glucose/fructose and ethanol concentrations were determ ined. 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, t he presence of up to 166 mM sugar yielded responses ranging between 30% enh ancement 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 sy nergism for some variables. The potential enological significance of these findings is discussed.