Hardman, John K. (National Heart Institute, National Institutes of Health, Bethesda, Md.) and Thressa C. Stadtman. Metabolism of omega-amino acids. V. Energetics of the gamma-aminobutyrate fermentation by Clostridium aminobutyricum. J. Bacteriol. 85:1326-1333. 1963.-Clostridium aminobutyricum utilizes gamma-aminobutyrate as its sole carbon, nitrogen, and energy source, producing ammonia, acetate, and butyrate as a result of this fermentation. Coenzyme A (CoA)-transferase, phosphotransacetylase, and acetokinase activities have been demonstrated in crude extracts of the organism; the coupling of the reactions catalyzed by these enzymes to the fermentation reactions provides a mechanism whereby C. aminobutyricum can obtain energy, in the form of adenosine triphosphate, from the decomposition of gamma-aminobutyrate. Indirect evidence of additional phosphorylation, at the electron-transport level, has been obtained from molar growth yield studies and from the inhibition by 2,4-dinitrophenol of butyrate synthesis from gamma-aminobutyrate and from crotonyl-CoA.