Peculiarities and systematics of microbial diglycosidases, and their applications in food technology.

Diglycosidases are endo-β-glucosidases that hydrolyze the heterosidic linkage of diglycoconjugates, thereby releasing in a single reaction the disaccharide and the aglycone. Plant diglycosidases belong to the glycoside hydrolase family 1 and are associated with defense mechanisms. Microbial diglycosidases exhibit higher diversity-they belong to the families 3, 5, and 55-and play a catabolic role. As diglycoconjugates are widespread in the environments, so are the microbial diglycosidases, which allow their utilization as nutritional source and carbon recycling. In the last 10 years, six microbial diglycosidases have been sequenced, and for two of them, the three-dimensional structure has been elucidated. This knowledge allowed the identification of their diverse phylogenetic origin, and gave insights into the understanding of the substrate specificity. Here, the last advances and the applications of microbial diglycosidases are reviewed. KEY POINTS: • Substrate specificity and phylogenetic relationships of diglycosidases are reviewed. • On-going and potential applications of diglycosidases are discussed.