Catabolite Repression

Many inducible operons are not only controlled by their respective inducers and regulatory genes, but they are also controlled by the level of glucose in the environment. The ability of glucose to control the expression of a number of different inducible operons is called CATABOLITE REPRESSION. Diauxic growth is when a common nutrient such as glucose is present it halts the synthesis of enzymes for an alternate carbon-energy source such as lactose. So here, high concentrations of glucose end up halting the production of enzymes for an alternate food source (lactose) through an inducible operon.