Variation of activity of bacterial diaminopimelate decarboxylase under different conditions of growth

Abstract

Minimal defined media produced bacteria with the highest diamino-pimelate-decarboxylase activities; supplementation with certain amino-acids or pyridoxine caused a reduction (repression) of activity of some species to the level found after growth in broth. L-Lysine caused repression in Escherichia coli and Aerobacter aerogenes, and in certain strains of Staphylococcus aureus. The enzyme in Bacillus subtilis and B. megaterium was not repressed. D-Lysine had no effect in S. aureus but caused a small increase of activity in E. coli. In E. coli, repression was also caused by pyrid oxine and any of the aromatic amino-acids (phenylalanine, tryptophan or tyrosine). These effects were additive with that of L-lysine. Pyridoxine and L-lysine had different effects on the time course of enzyme synthesis. Changes in the nature or amount of carbohydrate in the media had various effects on the amounts of enzyme. Young cultures had the highest activities, although enzyme continued to be formed until the end of logarithmic growth. Subsequently enzyme disappeared rapidly from E. coli and B. subtilis but not from S. aureus.