In the preceding communications^1),2),3) of this series, it was reported that L-glutamate was oxidized by the streptomycin-producing microorgnism, ^{Streptomyces griseus} K-I. The L-glutamate oxidation by the intact mycelium of S. griseus was reported in the previous paper³⁾.

The extraction of the soluble L-glutamic dehydrogenase from the freeze-dried powder²⁾ and the wet mycelium³⁾ of S. griseus was unsuccessful. It was believed that all procedures were rendered difficult, because S. griseus contained the excess amount of the slime substance. Sohler et al⁴⁾ demonstrated that S. griseus, S. fradiae, and Micromonospora among the genus Streptomyces were lyzed by lysozyme. There are many instances of the lysis of cell walls or the enzyme extraction by lysozyme, but the glutamic dehydrogenase is completely inactivated by this enzyme⁵⁾.

The author succeeded in obtaining the soluble L-glutamic dehydrogenase from the mycelium paste with aid of the fresh egg white under suitable conditions. In the present study, some results on L-glutamate oxidation by using this crude enzyme solution will be reported. In addition various phenomena of the L-glutamate oxidation by the intact mycelium and the crude enzyme solution of S. griseus will be discussed.