SUMMARY: 8602 was grown in continuous culture under steady-state conditions in a carbon-limited medium containing either 20 mM-acetamide or 20 mM-acetamide + 10 mM-succinate. The amidase specific activity was measured at various dilution rates and found to have a sharp peak at a dilution rate of 0.30–0.35 hr. Fully constitutive mutants (C 11 and L 9) gave curves for amidase activity with the highest values at very low dilution rates (0.05–0.10 hr) and these decreased as the dilution rate increased. A semi-constitutive mutant (C 17) gave a curve intermediate between that of the wild-type strain and the fully constitutive mutant (C 11). Mutants with decreased sensitivity to catabolite repression by succinate gave curves which declined less steeply at the higher dilution rates. Mutant L 9, a fully constitutive mutant with decreased sensitivity to catabolite repression, had higher specific activities than mutant C 11 at the equivalent dilution rates. Mutant L 11, an inducible mutant with decreased catabolite repressibility, had higher amidase specific activities at high dilution rates than the wild-type inducible strain. It is concluded that in continuous culture under steady-state conditions the specific activity of the inducible amidase of is determined by the balance between induction and catabolite repression and that catabolite repression is directly related to the growth rate of the culture.


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