ARGININE DEGRADATION BYMICROCOCCUS PYOGENESVAR.AUREUS

Whereas intact cells of a number of strains of M. pyogenes var. aureus rapidly degrade arginine to ornithine with no observable accumulation of citrulline, the latter amino acid is almost the sole ninhydrin-positive product of arginine degradation by acetone-dried cells of this species. Recovery of the products of arginine degradation shows that arginine is degraded to ornithine by intact cells with the liberation of two moles of ammonia and one of carbon dioxide and to citrulline by acetone-dried cells with the liberation of ammonia. It is concluded from the above observations that degradation of arginine to ornithine by M. pyogenes var. aureus proceeds via citrulline. Maximum activity of arginine-desimidase was observed at pH 6.5 and the quantity of enzyme within the cells was found to depend on the arginine concentration of the growth medium, with maximum enzyme formation at about 100 γ/ml. of arginine.