12/14/2007

DOE-JGI Microbial Genome Sequencing Project Leads to the Discovery of a New Carbon Dioxide Fixation Pathway

The assimilation of carbon dioxide (CO2) into organic material is quantitatively the most important biosynthetic process.

The Science

The December 14, 2007, issue of Science features a report that reveals a novel fifth pathway for carbon dioxide (CO₂) fixation used by the archaeon, Metallosphaera sedula. The real significance of this new finding is that novel additional mechanisms exist in the microbial world for carbon capture and cycling; exploitation of these strategies may lead to new opportunities and technologies to address critical DOE missions in bioenergy and carbon biosequestration. The discovery of this new pathway, distinct from the four previously identified pathways for growth on CO₂, including the well-known Calvin cycle that powers photosynthesis in plants and algae, was grounded in the sequencing of the genome of Metallosphaera sedula by the DOE Joint Genome Institute which provided the genetic “parts list” for comparison with genes known to be involved in the four previously known pathways for growth on CO₂ as a sole carbon source. Additional genome comparisons revealed that a number of other microbes possess this new pathway and in surveying the Venter Global Ocean Sampling database, an unexpectedly large number of “5^th-pathway” genes were observed, suggesting that this mechanism for carbon capture is much more widespread than suspected.

BER Program Manager

Ramana Madupu

U.S. Department of Energy, Biological and Environmental Research (SC-33)
Biological Systems Science Division
[email protected]

References

Berg, I. A., D. Kockelkorn, W. Buckel, and G. Fuchs. 2007. “A 3-Hydroxypropionate/4-Hydroxybutyrate Autotrophic Carbon Dioxide Assimilation Pathway in Archaea,” Science 318(5857), 1782. DOI:10.1126/science.1149976.