Photo courtesy of Iasin Anderson, JGI

   Methanogenic archaea have a major impact on global carbon cycling.   They are autotrophs, producing their cellular carbon from carbon dioxide, and they gain energy from methanogenesis, a process by which carbon dioxide and other one-carbon compounds are converted to methane.   Atmospheric methane, a greenhouse gas whose concentration is rapidly increasing, is derived largely from this process.

  Oxygen is highly toxic to methanogens, however they occupy a large variety of anaerobic environments.   Methanogens are commonly found associated with decaying organic matter where they catalyze the final step in its decomposition.   Members of the genus Methanoculleus are found commonly in marine and brackish environments, and they are among the most prevalent methanogens found in wastewater and sewage bioreactors and in landfills.   A metabolic feature of Methanoculleus species and some closely related genera but unique among the methanogens is the ability to use ethanol and a variety of secondary alcohols as electron donors for methanogenesis, and this may contribute to their dominance in biomethanation processes.

   Methanoculleus marisnigri belongs to the order Methanomicrobiales, the only order of methanogens for which no genome sequences have yet been determined.   JGI will be sequencing the genomes of two members of the Methanomicrobiales, M. marisnigri and a Methanocorpusculum species, and these two genomes will enable comparative genomic studies to determine how the Methanomicrobiales differ from other methanogens.

References:

Chachkhiani, M., Dabert, P., Abzianidze, T., Partskhaladze, G., Tsiklauri, L., Dudauri, T., and Godon, J. J. 2004. 16S rDNA characterization of bacterial and archaeal communities during start-up of anaerobic thermophilic digestion of cattle manure. Bioresour. Technol. 93, 227-232.

Huang, L. N., Zhou, H., Chen, Y. Q., Luo, S., Lan, C. Y., and Qu, L. H. 2002. Diversity and structure of the archaeal community in the leachate of a full-scale recirculating landfill as examined by direct 16S rRNA gene sequence retrieval. FEMS Microbiol. Lett. 214, 235-240.

Maestrojuan, G. M., Boone, D. R., Xun, L., Mah, R. A., and Zhang, L. 1990. Transfer of Methanogenium bourgense , Methanogenium marisnigri , Methanogenium olentangyi , and Methanogenium thermophilicum to the genus Methanoculleus gen. nov., emendation of Methanoculleus marisnigri and Methanogenium , and description of new strains of Methanoculleus bourgense and Methanoculleus marisnigri . Int. J. Syst. Bacteriol. 40, 117-122.

Romesser, J. A., Wolfe, R. S., Mayer, F., Spiess, E., and Walther-Mauruschat, A. 1979. Methanogenium , a new genus of marine methanogenic bacteria, and characterization of Methanogenium cariaci sp. nov. and Methanogenium marisnigri sp. nov. Arch. Microbiol. 121, 147-153.

Tonouchi, A.   2004.   Anaerobic 2-propanol degradation in anoxic paddy soil and the possible role of methanogens in its degradation.   Curr. Microbiol. 49, 75-78.