A survey of glycosidase activities of commercial wine strains of Oenococcus oeni.

Lactic acid bacteria play an important role in wine-making by undertaking the malolactic fermentation, yet little information is available on other aspects of their physiology, such as their profile of external enzymatic activities. In this study we sought evidence for the existence and action of glycosidase enzymes in wine isolates of Oenococcus oeni. This group of enzymes is of interest because of their potential for liberation of grape-derived aroma compounds from their natural glycosylated state. This comprehensive study reveals that these bacteria produce glycosidases that might be important in wine-making. Strains did not necessarily hydrolyse all substrates tested, but rather were grouped according to substrate specificity. Thus a subset comprising strains 2, 5 and 16 possessed high cumulative activities against beta-d- and alpha-d-glucopyranoside substrates, while a group comprising strains 4, 21 and 22 was noted for superior hydrolysis of beta-d-xylopyranoside, alpha-l-rhamnopyranoside and alpha-l-arabinofuranoside substrates. Key physico-chemical inhibitors of analogous systems from other microorganisms were seen to produce variable responses across the strains investigated here. Accordingly, several strains retained significant hydrolytic activity at typical wine pH values ( approximately 3.0-4.0), residual glucose and fructose contents (up to 20 g/L), and ethanol contents (up to 12%). These findings highlight the potential of O. oeni as a useful alternative source of glycosidase enzymes for use in wine-making.