The isolation and characterization of alkane-oxidizing organisms and the effect of growth substrate on isocitric lyase.

Abstract

SUMMARY A mycobacterium, two pseudomonads and a torula were isolated from soil using selective enrichment techniques in mineral salts-kerosene media. The properties of the organisms and their possible identity are outlined. Hydrocarbons, fatty acids, n-alcohols, dicarboxylic acids and acyl amides able to support growth were determined. Growth of the torula on hydrocarbons increased the ability of the organisms to oxidize other alkanes and fatty acids; the organism was, however, able to oxidize these substrates, at a slow rate, irrespective of the substrate of growth. When the torula was grown on an alkane with an even number of carbon atoms, there was no evidence that the induced enzymes favoured the oxidation of fatty acids with even rather than odd numbers of carbon atoms. Growth on hydrocarbons increased the amount of isocitric lyase present in all four micro-organisms, suggesting that β-oxidation of fatty acids derived from alkanes gives rise to acetyl-CoA and that this pathway and the glyoxylate bypass are important in the metabolism of alkanes.