Regulation of the formation of protease byBacillus megaterium

The formation of protease takes place in washed cells ofBacillus megaterium incubated in a nitrogen-free medium. The rate of enzyme synthesis is decreased much less than that of cell proteins as compared with growing cells. The synthesis of protease in a nitrogen-free medium requires the presence of glucose. The omission of glucose results in stopping of the enzyme formation and substantial decrease of the rate of protein synthesis. Protease is not synthesized when the washed cells are incubated in a phosphate, free medium. The incubation of the cells in a nitrogen-free medium results in a decrease of the concentration of amino acids in the pool. In a phosphate-free medium the content of free amino acids increases temporarily and decreases again later. When the culture grown in the medium containing threonine or threonine and isoleucine in addition to NH₄ ions is transferred into the medium without amino acids, no protease formation is found during derepression of enzymes synthesizing both amino acids. The cells grown in a medium containing casamino acids begin to form the enzyme after a short lag period when transferred into the medium containing NH₄ as a sole nitrogen source or into a nitrogen-free medium.