The synthesis of amino acids by Methanobacterium omelianskii

Publisher Website
Google Scholar
Abstract
Methanobacterium omelianskii was grown on 14CO2 and unlabelled ethanol, or on [l-14c]- or [2-14c]-ethanol and unlabelled carbon dioxide. The cell protein was hydrolyzed and certain of the amino-acids were isolated and degraded. Carbon from both carbon dioxide and ethanol is used for biosynthesis of amino-acids, and in most cases ethanol is incorporated as a C2 unit. Ethanol carbon atoms and carbon dioxide carbon atoms apparently enter the same range of compounds. Ethanol and carbon dioxide are equally important as sources of cell carbon. The origins of carbon atoms of aspartate, alanine, glycine, serine and threonine are consistent with the synthesis of these amino-acids, by pathways known to exist in aerobic organisms, from pyruvate arising by a C2+C1 condensation. The proportion of total radioactivity found in C-l of lysine, proline, methionine and valine is consistent with synthesis of these amino-acids by pathways similar to those found in Escherichia coli. Iso-leucine is probably formed by carboxylation of a C5 precursor formed entirely from ethanol. Glutamate is formed by an unknown pathway.