CONTRIBUTION OF GLYCOLYSIS TO CATABOLITE REPRESSION OF L-TRYPTOPHANASE SYNTHESIS IN ESCHERICHIA COLI

Catabolite repression of tryptophanase formation in E. coli K12 TAB40 was examined. Glycerol or pyruvate, if given as a sole carbon source, did not repress tryptophanase formation unlike glucose, but if they existed together, they repressed the enzyme formation like glucose. This synergistic effect was well observed in the wild strain of E. coli K12 and was pronounced also in β-galactosidase system.The combination of glycerol or pyruvate with other carbon sources directly related to glycolysis repressed the enzyme formation, while succinate or ribose did less effectively. When cells were grown on various carbon sources, glucose, glycerate, and fructose were effective in repressing the enzyme formation. It was considered that the growth rate and catabolite repression might not necessarily be directly related. Even anaerobically grown cells could show catabolite repression. Inhibition of oxidative pyruvate decarboxylation or TCA cycle provoked catabolite repression. Conclusively glycolytic steps may be associated with catabolite repression of tryptophanase synthesis.