Abstract
Behaviours of acetone-butanol fermentation bacterium, Clostridium acetobutylicum, towards optically active lactic aci4ls were investigated. As a rule, cells harvested from lactic acid supplemented culture medium surpassed in metabolizing lactic acid as compared with glucosegrown cells. It was pointed out that Cl. acetobutylicum possessed D-lactic dehydrogenase by nature, and that L-lactic acid could be dehydrogenated after its conversion to D-isomer through the action of racemiase. In addition to D-lactic dehydrogenase, it was further indicated that this organism had another type of lactic dehydrogenase or oxidase, which was capable of oxidizing L-isomer with air oxygen in liberating acetic acid and carbon dioxide. Physiological action of racemiase as a mediator between two lactic enzymes, lactic dehydrogenase and. D-lactic acid oxidizing enzyme, was ascertained.
In addition, it is mentioned about pyruvic oxidase and partial inhibition by cyanide to lactic dehydrogenase.
