Abstract
In this paper, the decomposing mechanism of L-ascorbic acid by bacterium, which belong to Micrococcus species, isolated by this author, was studied. It was observed that when the cells were incubated in the synthetic medium which contained glucose and ascorbic acid as carbon sources, the decomposition of ascorbic acid began after the induction period succeeding to a complete decomposition of glucose. On the other hand, the cells grown in ascorbic acid containing medium could decompose ascorbic acid rapidly to CO_2 and H_2O, while the cells grown in glucose containing medium had no ascorbic acid decomposing activity. From the above mentioned results, it was supposed that the enzymes responsible for the decomposition of ascorbic acid were shown to be adaptive in nature, and this presumption was supported by the experiment that the adapted cells could decompose dehydroascorbic acid, while the unadapted ones could not. It was estimated, too, that the first step of ascorbic acid metabolism by adapted cells might be carried through the course of ascorbic acid→dehydroascorbic acid→ diketogulonic acid. Unadapted cells, also, were supposed to contain some enzymes which catalyzed the oxidation of ascorbic acid to dehydroascorbic acid under an aerobic condition and inhibition of which activity caused by 2,4-dinitrophenydrazine (10^<-3> or 10^<-4> M). As_2O_2 (10^<-3'>M), KCN (10^<-4> M), and NaN_3 was studied by Warburg's manometric method.
