Archaea Genomes - METHANOSARCINA BARKERI

Methanosarcina barkeri sp. fusaro is a methanogenic Archaebacterium. Methanogens are organisms that make methane (can make their own energy only by methanogenesis) via a unique metabolic pathway. Most methanogens can make methane from carbon dioxide and hydrogen gas however some can use other 1-carbon compounds, such as carbon monoxide or formic acid, and a few others can use acetate and methylamines.

The fusaro strain of M. barkeri was isolated from mud samples taken from the freshwater lake Lago del Fusaro near Naples (Italy). Methanosarcina barkeri are lobed cocci.

It has been reported that Methanosarcina barkeri sp. fusaro live in the rumen of cattle. The rumen is where microbial populations collaborate to digest cellulose and other polysaccharides, producing carbon dioxide, methane and organic acids. There is no oxygen in the rumen and these organisms are very oxygen sensitive. Therefore, M. barkeri is an classed as an extreme anaerobe. The ecruate consists of up to 35% methane and 65% carbon dioxide. Average daily production of gas from a cow is about 100-150 L a day. A well-fed dairy cow can generate as much as 500 L of gas daily. Methane gas from cows could be a major contributor to the problem with the ozone layer

A new amino acid has been discovered in Methanosarcina barkeri. The amino acid, called pyrrolysine, is genetically encoded by a nucleotide sequence that normally halts the translation of mRNA—a stop codon. But during the assembly of certain proteins, researchers have found, cells override the stop codon, incorporate pyrrolysine, and continue to synthesize protein.

References:

http://genome.jgi-psf.org/draft_microbes/metba/metba.home.html
http://web.umr.edu/~microbio/BIO221_1998/M_barkeri.html
http://www.genomenewsnetwork.org/articles/05_02/amino_acid.shtml