Penicillinamidohydrolase inEscherichia coli

The differential rate of synthesis of penicillinamidohydrolase (penicillin acylase — EC 3.5.1.11) was studied inEscherichia coli growing in some chemically defined media and in a complex medium. The enzyme is synthesized at a constant rate only during the exponential phase of growth of cells. Its synthesis is induced most effectively (with respect to quantity) by phenylacetic acid. The induction lag of the enzyme synthesis in a medium with acetate corresponds to two generation times. The highest rate of the enzyme synthesis is reached in a medium containing phenylacetic acid as the only source of carbon and energy. The enzyme synthesis is fully repressed by an increased concentration of dissolved oxygen in the medium, even whenEscherichia coli is cultivated in the medium with phenylacetic acid as the only carbon and energy source.