methanogenium marinum methanogenium marinum methanogenium marinum is a psychrophilic, h2-using methanogen from skan bay, alaska. its cells are highly irregular, non-motile coccoids (diameter, 1 to 1.2 μm), occurring singly. ak-1 is its type strain. methanogenium marinum scientific classification domain: archaea kingdom: euryarchaeota phylum: euryarchaeota class: methanomicrobia order: methanomicrobiales family: methanomicrobiaceae genus: methanogenium species: m. marinum binomial name methanogenium marinumchong et al., 2002 morphology the cells are highly irregular and coccoid in shape and non-motile, 1 to 1.2 μm in diameter. like other species within the genus methanogenium, they are strictly anaerobic.