beta-galactosidase

…enzyme of this type is β-galactosidase. Escherichia coli growing in nutrient medium containing glucose do not utilize the milk sugar, lactose (glucose-4-β-d-galactoside); however, if the bacteria are placed in a growth medium containing lactose as the sole source of carbon, they synthesize β-galactosidase and can therefore utilize lactose. The reaction…

coli to form β-galactosidase when transferred to a medium containing lactose as the sole carbon source; such a transfer may result in an increase of 1,000-fold or more in the cellular concentration of the enzyme. Because this preferential enzyme synthesis is elicited by exposure of the cells to…

, β-galactosidase in Escherichia coli), occurs when cells are exposed to the substance (substrate) upon which the enzyme acts to form a product.