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Acetogenic Bacteria

  1. Volker Müller,
  2. Janin Frerichs

Published Online: 20 SEP 2013

DOI: 10.1002/9780470015902.a0020086.pub2

eLS

eLS

How to Cite

Müller, V. and Frerichs, J. 2013. Acetogenic Bacteria. eLS. .

Author Information

  1. Johann Wolfgang Goethe University, Frankfurt, Germany

  1. Based in part on the previous version of this eLS article ‘Acetogenic Bacteria’ (2007) by Frank Imkamp and Volker Müller.

Publication History

  1. Published Online: 20 SEP 2013

Abstract

Acetogenic bacteria are a specialised group of strictly anaerobic bacteria that are ubiquitous in nature. Together with the methane-forming archaea they constitute the last limbs in the anaerobic food web that leads to the production of methane from polymers in the absence of oxygen. Acetogens are characterised by a unique pathway, the Wood–Ljungdahl pathway of carbon dioxide reduction with the acetyl-CoA synthase as the key enzyme. This pathway also allows chemolithoautotrophic growth on hydrogen and carbon dioxide and it is the only pathway known that combines carbon dioxide fixation with adenosine triphosphate (ATP) synthesis. Thus, it is considered the first biochemical pathway on earth. ATP is synthesised by a chemiosmotic mechanism with Na+ or H+ as coupling ion, depending on the organism. In cytochrome-free acetogens, energy is conserved by ferredoxin reduction followed by ferredoxin-dependent Na+ (or H+) translocation across the membrane (Rnf complex). Acetogens may represent ancestors of the first bioenergetically active cells in evolution.

Key Concepts:

  • Acetogenic bacteria are a specialised group of anaerobic bacteria producing acetate via the Wood–Ljungdahl pathway.

  • Acetogenic bacteria are widespread in nature and are an essential link in the anaerobic mineralisation of organic matter.

  • Acetogenic bacteria are nutritionally versatile and can grow heterotrophically as well as lithoautotrophically.

  • Lithoautotrophic growth on hydrogen and carbon dioxide leads to acetate production coupled to ATP synthesis by a chemiosmotic mechanism.

  • The bioenergetic pathway and the coupled fixation of carbon into biomas links acetogens to early evolutionary processes and maybe even to the first living cell on earth.

  • The capability of acteogens to produce acetate from H2+CO2, CO, or a mixture of H2+CO2+CO (syngas) makes these organisms the prime candidates for biotechnological applications.

Keywords:

  • metabolism;
  • Wood–Ljungdahl pathway;
  • carbon dioxide fixation;
  • bioenergetics;
  • ATP synthesis;
  • Rnf complex;
  • electron bifurcation;
  • syngas fermentation;
  • biotechnology