Methanococcus  

What you should know:

Methanococcus is a Gram-negative member of the Archaea with a protein cell wall.  It produces methane by oxidizing H₂ gas and reducing CO₂ to CH₄. Methanogens are anaerobes that inhabit, among others, the rumen of cows, where they can produce up to 400 liters of methane per day!

Classification: 

Domain Archaea 

    Phylum Euryarchaeota

        Class Methanococci

Bergey's Manual Volume 1: The Archaea and the deeply brancing and phototrophic Bacteria

links

• http://microbewiki.kenyon.edu/index.php/Methanococcus