Fig. 2

Distribution of COG genes in categories significantly different than the RefSeq Sample. The fraction of proteins in each methanogen belonging to COG categories shown differ significantly compared to the RefSeq sample. All four sequenced methanogens have significantly more genes categorized as energy production and conversion and coenzyme transport and metabolism, which confirms the observation that the methanogens have a confirmed shift towards energy conservation in order to occupy their ecological niche. Significance was determined through Fisher’s exact test, and verified through difference of medians analysis [24], * represents p < 0.01