Induction and Repression of Pseudomonas aeruginosa Amidase

Abstract

The synthesis of an inducible amidase by Pseudomonas aeruginosa 8602/a was studied in cultures growing exponentially in succinate medium. Induction by both the substrate inducer acetamide, and the non-substrate inducer N-acetylacetamide, was repressed by cyanoacetamide. Induction by 10^-2mN-acetylacetamide was significantly repressed by 10^-4m-cyanoacetamide, but repression of induction by 10^-3m-acetamide required a tenfold excess of cyanoacetamide. Amidase synthesis in a medium in which acetamide was the sole carbon + nitrogen source was also repressed by cyanoacetamide, which under these conditions inhibited the growth of non-induced bacteria. Several tricarboxylic acid cycle intermediates, and related compounds, repressed amidase synthesis in exponentially growing organisms. Catabolite repression by propionate in succinate medium was decreased by increasing the concentration of acetamide. These findings are discussed in relation to general theories of regulation of microbial enzyme synthesis.