EXCRETION OF PYRUVIC AND ALPHA-OXOGLUTARIC ACID BY STR RIMOSUS

Submerged cultures of Str. rimosus excrete pyruvic and α-oxoglutaric acid in glucose-containing mediums in the presence of casaminoacids. After buffering with carbonates the amounts of keto acids increase about threefold. N-free cultures show smaller amounts of keto acids, but after 24 h we can see an antagonistic behaviour of both curves: pyruvic acid is converted stoichiometrically to oxoglutaric acid. Succinate and α-oxoglutarate delay the secondary reception of pyruvate without changes in primary excretion. Replacement of glucose by glycerine-containing cultures shows that pyruvate excretion is not due to a glucose-effect in the sense of enzyme-repression. NH4-ions depress, pyruvate-excretion and induce a very good growth. A NH4-dependent pyruvate peak appears only in the presence of succinate. The excretion of keto acids by Streptomycetes is caused by two unequal metabolic disturbances: the initially inhibited pyruvate-oxidation with failed pyruvate dehydrogenase, and the associated competition from pyruvate and/or α-oxoglutarate oxidation based on a previously formulated regulation principle. © 1968 Springer-Verlag.