Identification of Bacillus strains producing glycosidases active on rutin and grape glycosidic aroma precursors

Most of the glycosidic aroma precursors in grape consist of diglycosides such as rutinoside. Yeast glycosidases have been extensively studied but their activity is limited to monoglucosidic precursors. Yet, there is no study about application of glycosidases active on rutinoside in grape. In this study, we screened Bacillus isolates for their glycosidase activities on rutin and grape aroma precursors. One Bacillus amyloliquefaciens and one Bacillus licheniformis strains produced extracellular glycosidases, active on both rutin and para-nitrophenol-α-l-rhamnoside. The specific rutinosidic activities were 6.2 and 4.1 pkat/mg respectively, and supernatants were active on Muscat grape glycosidic aroma precursors. Both strains were able to release monoterpenoids and benzenoids. The most released monoterpenoid in grape pomace was neric acid, with 378 μg/kg and the most released benzenoid was 2-phenylethanol, with 189 μg/kg for B. licheniformis. These glycosidases are interesting tools to target rutinosidic glycosides in grape and can be applied as a new way for valorising grape pomace.