Is involved in the biosynthesis of trehalose but not in that of capsular glucan and glycogen. hydrolysis of (1->4)-alpha-D-glucosidic linkage in 4-alpha-D-[(1->4)-alpha-D-glucanosyl]n trehalose to yield trehalose and (1->4)-alpha-D-glucan. Glycan biosynthesis; trehalose biosynthesis. Inactivation of treZ does not affect the production of both capsular alpha-D-glucan and glycogen. Cells lacking this gene are not affected in their multiplication or persistence in the BALB/c mouse infection model. Belongs to the glycosyl hydrolase 13 family.