The metabolism of glycerol in Mycobacterium butyricum

Abstract

The metabolism of glycerol was studied quantitatively in cultures of M. butyricum grown on a synthetic medium containing [Cl4]g]ycerol or non-isotopic glycerol accompanied by [Cl4]bicarbonate or [Cl4]acetate. The organism excreted a considerable amount of 2-oxoglutaric acid into the medium. The incorporation of C14 into the bacteria and some of their extracellular products was determined. Total degradation of the 2-oxoglutaric acid formed in the presence of sodium [Cl4]bicarbonate gave a labelling pattern consistent with the fixation of CO2 in the [beta]-carboxyl group of precursor oxaloacetate; and the patterns found in the presence of [l-C14]- or [2-C14]-acetate are consistent with oxidation of acetate in the citric acid cycle. The distribution of C14 in the 2-oxoglutaric acid formed in the presence of [1:3-Cl42] glycerol is consistent with the scheme: 2 glycerol [forward arrow] 2 pyruvate [forward arrow] oxaloacetate + acetate [forward arrow] 2-oxoglutarate + CO2. The scheme is discussed in detail.