The effect of adaptation on the activity of the dehydrogenases of Bact. lactis aerogenes

Abstract

The Thunberg (methylene blue reduction) method has been used to determine changes in dehydrogenase activity occurring when Bacterium lactis aerogenes undergoes various adaptations. Adaptation to a new carbon source gives specifically increased dehydrogenase activity towards that particular substance. Cells trained to glycerol show no parallel increase in ability to oxidize other polyhydric alcohols, nor do those trained to sucrose give increased oxidation of other disaccharides; lactose-trained bacteria show improved lactose oxidation and somewhat better sucrose oxidation. Adaptation to moderate cone, of crystal violet or proflavine brings about no change in the power to oxidize glucose, lactose, formate, and glycerol. Adaptations to higher concs. cause changes in the ability to oxidize glycerol and formate, a decrease with crystal violet and an increase with proflavine. Adaptation to sulfanilamide had no effect on its properties of oxidation. When trained to K tellurite the bacteria, though normal in their oxidation properties when young, lose all their dehydrogenase activity long before they cease growing.