Substrate-dependent regulation of carbon catabolism in marine sulfate-reducing Desulfobacterium autotrophicum HRM2

J Mol Microbiol Biotechnol. 2010;18(2):74-84. doi: 10.1159/000277655. Epub 2010 Jan 23.

Abstract

Desulfobacterium autotrophicum HRM2 is a metabolically versatile sulfate-reducing bacterium, capable of heterotrophic (e.g. with organic acids and alcohols) and chemolithoautotrophic growth (with H(2)/CO(2)). It employs the Wood-Ljungdahl pathway for complete oxidation of acetyl-CoA to CO(2) and for CO(2) fixation. Here, we investigated substrate-dependent regulation at different levels of anaerobic carbon catabolism in this bacterium. (a) Whole-cell adaptation studies indicated an inducibleutilization of short-chained alcohols, agreeing with a substrate-specific abundance increase (up to 40-fold) of alcohol dehydrogenase Adh4. Simultaneous utilization of lactate and 1-propanol was paralleled by adh4 expression and Adh4 formation, respectively. (b) Degradation of propionate generally involves methylmalonyl-CoA mutase (Sbm). Expression of sbm was upregulated during growth with 1-propanol, but not with a mixture of lactate and 1-propanol. Correspondingly, propionate was excreted during growth with this substrate mixture. (c) CO dehydrogenase, the key enzyme of the Wood-Ljungdahl pathway, is encoded by several genes (cdhC, cdh1 and cdh2) located at different genomic positions. Expression of all of these genes during heterotrophic and autotrophic growth points to a reversible operation of the Wood-Ljungdahl pathway. In summary, the different regulatory patterns displayed by Db. autotrophicum HRM2 at the tested metabolic levels point to a multi-layered regulatory network.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 1-Propanol / metabolism
  • Alcohol Dehydrogenase / biosynthesis
  • Alcohols / metabolism
  • Aldehyde Oxidoreductases / biosynthesis
  • Anaerobiosis
  • Carbon / metabolism*
  • Deltaproteobacteria / metabolism
  • Deltaproteobacteria / physiology*
  • Gene Expression Regulation, Bacterial*
  • Lactic Acid / metabolism
  • Multienzyme Complexes / biosynthesis
  • Oxidation-Reduction
  • Propionates / metabolism
  • Sulfates / metabolism

Substances

  • Alcohols
  • Multienzyme Complexes
  • Propionates
  • Sulfates
  • Lactic Acid
  • Carbon
  • 1-Propanol
  • Alcohol Dehydrogenase
  • alcohol dehydrogenase IV
  • Aldehyde Oxidoreductases
  • carbon monoxide dehydrogenase