In the previous investigations^1),2) on the effect of various antibiotics upon the aerobic carbohydrate metabolism of E. coli or P. fluorescens, it was observed that dihydrostreptomycin greatly diminished the yield of α-ketoglutarate from various carbon compounds without causing any inhibiting effect on oxidation of substrates and furthermore only antibiotically active derivatives of streptomycin produced a remarkable accelerating effect on oxidative decomposition of α-ketoglutarate.

Considerable informations have been presented on the inhibitory actions of streptomycin on bacterial oxidation of a number of amino acids and of intermediates in carbohydrate metabolism. Among discussions regarding to the mechanism of the inhibiting action of streptomycin, forcefully advanced suggestion was proposed by Umbreit and his coworkers^3),4),5), who supposed that streptomycin would inhibit the condensation of pyruvate and oxalacetate to a seven-carbon compound which could not operate through the citrate shunt. Many investigators^{6),7),8),9),10)} showed that streptomycin also interfered anaerobic metabolism of pyruvate.

In the present paper, effects of dihydrostreptomycin on the anaerobic metabolism of pyruvate (or glucose) were examined with a strain of E. coli which revealed a strong activity of α-ketoglutarate-formation from pyruvate (or glucose) under aerobic conditions.