What does beta galactosidase normally break down?

Beta galactosidase typically catalyzes the hydrolysis of lactose. It cleaves the lactose molecules to form galactose and glucose which subsequently enter the glycolysis pathway. Beta galactosidase can also catalyze the conversion of lactose to allolactose through transglycosylation. Subsequently, the allolactose is broken down into its monosaccharide components. Allolactose plays a key role in the process by binding to the lacZ repressor, and forms a positive feedback loop which modulates the cellular levels of beta galactosidase; allolactose is the inducer for the lac operon.