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Abstract
Nocardia opaca, Xanthobacter autotrophicus and 18 representative strains of the genus Alcaligenes were examined for the presence of NAD-dependent dehydrogenases for lactate, ethanol or 2,3-butanediol after the cells had been transiently cultivated under conditions of oxygen deficiency. Formation of these enzymes was derepressed in all strains except Nocardia opaca and Alcaligenes latus. The protein patterns of Alcaligenes hydrogenophilus and Alcaligenes eutrophus type strain and strains N9A, H16, B19, H1 and H20 obtained by PAGE were similar. The purified lactate dehydrogenases from these strains were strongly inhibited by 1 to 5 μm-oxaloacetate, had a broad substrate specificity and a high affinity for MatrexTM Gel Green A. Alcaligenes faecalis shared the properties of the lactate dehydrogenase but differed greatly with respect to its protein pattern. In A. eutrophus strain A7 a high activity of lactate dehydrogenase was detected, but the enzyme was not sensitive to oxaloacetate.
Alcohol dehydrogenase and 2,3-butanediol dehydrogenase were even more widely distributed than lactate dehydrogenase among the strains studied. In many cases the electrophoretic mobilities of both alcohol dehydrogenases were identical. The study results in the following taxonomical conclusions. Alcaligenes eutrophus type strain and strains N9A, H16, B19, H1 and H20 are almost identical with respect to protein and enzyme patterns as well as the presence of a derepressible L(+)-lactate dehydrogenase sensitive to oxaloacetate. The strains CH34, 707, A7 and JMP134 differ greatly from this core group and from each other and have to be considered as aberrant strains of A. eutrophus.
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