Catalyzes the hydrolysis of alpha,alpha-trehalose into two molecules of D-glucose. alpha,alpha-trehalose + H2O = alpha-D-glucose + beta-D-glucose Inhibited by validamycin A. kcat is 63.0 sec(-1). Optimum pH is 3.7. Active within a narrow range of acidic pH values (pH 3.3 to 4.0). Optimum temperature is 60 degrees Celsius. Glycan degradation; trehalose degradation; D-glucose from alpha,alpha-trehalose: step 1/1. Monomer. Belongs to the glycosyl hydrolase 15 family.