Methanotrophic
Methanotrophic organisms use methane as a carbon source for growth and they use aerobic respiration to make ATP using reducing equivalents released by methane oxidation. Since all of the well characterised methanotrophs are aerobic organisms it is not surprising that they don't occur in association with methanogens and their presence in the reticulo-rumen has not been recorded. Just recently however evidence has been obtained strongly suggesting the co-existence of methanogens and methanotrophs in anaerobic submarine sediments 500 meters below the surface of the sea offshore from northern California (Hinrichs et al., 1999, Nature 398, 802-805). The metabolism of these methanotrophic organisms has not been characterised but, as the authors note, the finding "represents a substantial reassessement of archaeal metabolic capabilities".