Department of Applied Biology, The University of Hull
Abstract
1.Dicarboxylic acid metabolism was investigated in the alkane-utilizing bacterium Corynebacterium 7E1C.2.The best yields of dicarboxylic acid were obtained during growth on dodecane although significant amounts of tetradecanedioic acid were produced during growth on methyl myristate. No dicarboxylic acid was produced during growth on hexadecane, methyl palmitate or 16-hydroxypalmitate.3.Corynebacterium 7E1C possesses constitutive NAD+-dependent and NADP+-dependent alcohol dehydrogenases active with mono-ol, a, w-diol and (L)-hydroxyfatty acids. Additional NADP+-dependent octanol dehydrogenase activity was detected after growth on alkyl-containing substrates.4.Corynebacterium 7E1C possesses a constitutive acyl-CoA thioesterase active with monocarboxyl-, w-hydroxymonocarboxyl- and dicarboxyl-CoA esters. Long chain-length acyl-CoAs are the preferred substrates.5.Corynebacterium 7E1C possesses constitutive acyl-Con synthetase(s) active with monocarboxylic, w-hydroxymonocarboxylic and dicarboxylic-acids.6.Corynebacterium 7E1C possesses a constitutive ß-oxidation system. Long chain monocarboxyl-CoA esters and 16-hydroxypalmitoyl-CoA are good ß-oxidation substrates whereas short chain monocarboxyl-CoAs, long chain dicarboxyl-CoAs and 12-hydroxylauroyl-CoA are poor 5-oxidation substrates. Significant accumulation of saturated ß-oxidation intermediates occurred during the 9-oxidation of palmitate by cell-free extracts. When hydroxyacyl-CoA dehydrogenase was inhibited, hexadecenoyl-CoA and 3-hydroxypalmitoyl-CoA accumulated.7. The specificities of these enzyme systems are consistent with the range of dicarboxylic acids accumulated by this organism
