Adenosine Triphosphate Pools in Methanobacterium

Abstract

Certain aspects of adenosine triphosphate (ATP) metabolism in the strict anaerobe Methanobacterium strain M.o.H. have been investigated. Results of growth yield studies suggest that ATP conservation is very inefficient (0.06 mole of ATP per mole of hydrogen) under the conditions used to grow the bacterium in a fermentor. Experiments designed to demonstrate net ATP formation in cell-free extracts were negative. In whole-cell studies, substances which decreased ATP pool levels and increased adenosine monophosphate (AMP) pool levels were air, chloroform, 2,4-dinitrophenol, carbonylcyanide- m -chlorophenylhydrazone, and pentachlorophenol. The results suggest that the latter compounds act either as inhibitors of electron transport or as uncouplers of an energy-linked process. All the above compounds also inhibit methane formation in cell-free extracts, an ATP-requiring process. Methods are described for estimation of ATP, adenosine diphosphate (ADP), and AMP in whole cells, with a sensitivity in the range of 10 to 200 pmoles. An apparatus for quick sampling from an anaerobic suspension of whole cells also is described.