Springer Online Journal Archives 1860-2000
Abstract The role of β-galactosidase repression in glucose inhibition of lactose utilization was studied inEscherichia coli. Escherichia coli 3300 constitutively produces β-galactosidase even in the presence of glucose. When this strain was grown in a mixture of glucose and lactose, lactose utilization did not occur until glucose was depleted. The addition of glucose to a 3300 culture grown in lactose immediately caused a permanent inhibition of lactose utilization and only a mild transient repression of β-galactosidase. Exogenous cyclic adenosine monophosphate (AMP) did not overcome the glucose inhibition of lactose utilization but did relieve the transient repression. Thus glucose inhibition of lactose utilization is not related to β-galactosidase repression and is independent of cyclic AMP.
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