Regulative Beeinflussung der Nourseothricinbiosynthese durch O‐Aminobenzoesäure in Kulturen des Streptomyces noursei JA 3890b

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Abstract
The biosynthesis of nourseothricin, a streptothricin type antibiotic, is strongly stimulated by o‐aminobenzoic acid in cultures of S. noursei JA 3890 b. o‐Aminobenzoic acid (OAB) was shown to interfere with the amino acid metabolism and to influence last not least the efficacy of the precursor supplying system in the antibiotic biosynthesis. Thus, mycelium cultivated in presence of OAB (7.5 mM) exhibits strongly increased activities of NADP‐specific glutamate dehydrogenase. Simultaneously, this effector prevents the induction of alanine dehydrogenase in productive cultures suggesting that an enhanced formation of alanine interferes with antibiotic biosynthesis. Insignificant variations of further enzymic activities, e.g. of transaminases, of phosphoenolpyruvate carboxylase and of enzymes of the tricarboxylic acid cycle were observed. Furthermore, the possible role of o‐aminobenzoic acid as an effector of metabolite transport systems or of energy metabolism is discussed.