Bacteria Genomes - CHLOROBIUM TEPIDUM

Chlorobium tepidum is a thermophilic Gram-negative green sulfur bacterium isolated from a hot spring in New Zealand in which it forms a dense mat. The bacterium carries out photosynthesis in ways that are different from plants and other bacteria. Unlike plants, the green bacteria do not produce oxygen from photosynthesis.

According to some researchers, photosynthesis may have its evolutionary origins in organisms like C. tepidum. Such species would have been able to harvest energy from light at a time when the Earth's atmosphere had little oxygen. In addition, the organisms' ability to grow in low-light environments may have helped them limit their exposure to UV irradiation, which was likely at higher levels in the early days of Earth.

The ability of C. tepidum to fix atmospheric nitrogen, and its reliance on sulfur compounds for its photosynthetic processes make this species an important model for understanding the role microbes play in global nutrient cycles. The C. tepidum TLS strain grows optimally at 48C with a doubling time of about 2.5 hours.

The US Department of Energy funded the sequencing project as part of a larger effort to understand microbes that play a role in global energy and nutrient cycles. Chlorobium tepidum TLS is the first member of the green-sulfur group to be fully sequenced and it is now being used to investigate the origin and mechanisms of photosynthesis to see how these microbes might be used as alternative sources of energy.

References:

Proc. Natl. Acad. Sci. U.S.A 99 (14):9509-14 (2002)
http://www.kazusa.or.jp/cyano/Chlorobium/about.html
http://www.genomenewsnetwork.org/articles/07_02/tepidum.shtml