Ferredoxin- and Nicotinamide Adenine Dinucleotide-Dependent H 2 Production from Ethanol and Formate in Extracts of S Organism Isolated from “Methanobacillus omelianskii”

Abstract
S organism ferments ethanol to acetate and H2 but grows poorly on ethanol unless the partial pressure of H2 is kept low, as when it is grown in combination with an H2-utilizing methanogenic bacterium. The present study shows that S organism contains an alcohol dehydrogenase and a formate dehydrogenase, both of which require nicotinamide adenine dinucleotide (NAD) for activity. Hydrogen is evolved from NADH generated by these activities via a ferredoxin-dependent oxidation of NADH to NAD and H2. NADH:NADP oxido-reductase activity was also demonstrated. The relationship of these activities to the growth of S organism is discussed.