‘That which does not kill us only makes us stronger’: the role of carbon monoxide in thermophilic microbial consortia
Article first published online: 23 FEB 2009
© 2009 The Authors. Journal compilation © 2009 Society for Applied Microbiology and Blackwell Publishing Ltd
Volume 11, Issue 5, pages 1027–1037, May 2009
How to Cite
Techtmann, S. M., Colman, A. S. and Robb, F. T. (2009), ‘That which does not kill us only makes us stronger’: the role of carbon monoxide in thermophilic microbial consortia. Environmental Microbiology, 11: 1027–1037. doi: 10.1111/j.1462-2920.2009.01865.x
- Issue published online: 24 APR 2009
- Article first published online: 23 FEB 2009
- Received 19 September, 2008; accepted 10 November, 2008.
Carbon monoxide (CO), while a potent toxin, is also a key intermediate in major autotrophic pathways such as methanogenesis and acetogenesis. The ability of purple sulfur bacteria to use CO as an energy source was first described by Uffen in 1976. The prototype extremely thermophilic carboxydotroph Carboxydothermus hydrogenoformans was described in 1991. Eight bacteria and one archaeon that utilize CO have since been isolated and described from diverse geothermal environments. They derive energy from the oxidation of CO with water to form CO2 and H2. Most of these isolates thrive with headspace CO partial pressures around 1 atm, which is grossly elevated relative to CO concentrations in geothermal effluents. To account for this, we suggest that under consortial growth conditions the carboxydotrophs occupy microniches in which biogenic CO accumulates locally to high concentrations. CO oxidizers dissipate these potentially toxic CO hot spots with the production of H2, CO2 and acetate whose subsequent oxidation fuels other thermophiles. The identification of genes related to anaerobic CO oxidation in many metagenomic databases attests to widespread distribution of carboxydotrophs. Current evidence suggests that CO-oxidizing bacteria and archaea hold a vital niche in thermophilic ecosystems.