Extracellular production of proteins by microorganisms. III. Effect of glycine and L-isoleucine on protein production by Bacillus brevis No. 47.

Abstract

Among factors affecting the protein production by Bacillus brevis No. 47, glycine and L-isoleucine were found to be prominent in stimulating protein production. The simultaneous addition of appropriate amount of these amino acids resulted in the largest accumulation of proteins; namely, 12g/liter. The mode of action of glycine and isoleucine appeared different. Isoleucine stimulated the synthesis of both extracellular and intracellular proteins, while glycine caused a considerable increase of extracellular protein accumulation with a concomitant decrease in the amount of intracellular protein. Therefore, glycine may have a function in stimulating protein excretion. Glycine made cells more sensitive to lysozyme and caused a large decrease in alanine content of the cell wall fraction. These findings supported the possibility that glycine alters cell wall structure in such a way so as to facilitate protein excretion. The proteins produced in the presence of glycine as a whole were smaller in molecular weight than those without glycine. Amino acid composition of the proteins produced was same regardless of the presence or absence of glycine.