A particulate preparation from extracts ofAerobacter aerogenesoxidized 2-deoxy-D-glucose to 2-deoxy-D-gluconate, 6-deoxy-6-fluoro-D-glucose to 6-deoxy-6-fluoro-2-keto-D-gluconate, andD- andL-lactate to pyruvate.The oxidations ofD-gluconate andD- andL-lactate were found to be different with regard to pH of optimum activity, and to various inhibitory compounds. On the basis of these and other observations, it is suggested that the three substrates were oxidized by different enzyme systems. Other results suggest that the oxidation reactions were catalyzed by flavoprotein enzymes.