a 6-phospho-beta-D-galactoside + H2O = an alcohol + D-galactose 6-phosphate Inhibited by both galactose-6-phosphate and ATP. Optimum pH is 7.0-7.5. Carbohydrate metabolism; lactose degradation; D-galactose 6-phosphate and beta-D-glucose from lactose 6-phosphate: step 1/1. Induced during growth on lactose or lactulose. Belongs to the glycosyl hydrolase 1 family.