Round cells (1 micron in diameter) in pairs, tetrads or clusters. Gram-positive, non-motile.Mesophilic. The energy for growth is obtained by using one mole of H2 to reduce one mole of methanol to one mole of CH4. No production of methane in the absence of H2 and methanol.No other alcohol may replace methanol. Carbon monoxide CO and acetate are required for growth and some B vitamins The G+ C content of DNA is 26 mol%. Two species,Methanosphaera stadtmaniae (TC Stadtman, American microbiologist) isolated from human faeces.
