Biochemical characteristics of non‐streptomycin‐producing mutants of Streptomyces griseus I. Role of NAD (P)‐glycohydrolase in cell differentiation

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Abstract
Five non‐streptomycin‐producing mutants of an industrial strain of Streptomyces griseus lacking aerial mycelium formation were compared with their genetic ancestor and another producing mutant with regard to the NAD(P)‐glycohydrolase activity during cultivation on different media. By contrast to producing strains, all the Str− Amy− mutants displayed much lower mycelial and extracellular levels of enzyme, thus confirming earlier contentions concerning its involvement in the regulation of aerial mycelium formation. A tentative model is shown of the mechanism of control by phospho‐adenosinediphospho‐ribose of the intermediary metabolism at the sites of the citric acid cycle and the catabolism of the carbohydrates during distinct stages of cell differentiation. On the other hand, in the producing strain the biosynthesis of NAD(P)‐glycohydrolase was demonstrated to depend on the regime of fermentation. Repeated stages of submerged cultivation in stirred fermentors resulted in suppression of enzyme formation without concomitant change of the mycelial capacity to produce streptomycin. This suggests that there is no direct involvement of NAD(P)‐glycohydrolase in the control of antibiotic biosynthesis.