methanogenium methanogenium methanogenium is a genus of archaeans in the family methanomicrobiaceae. the type species is methanogenium cariaci. methanogenium scientific classification domain: archaea kingdom: euryarchaeota phylum: euryarchaeota class: methanomicrobia order: methanomicrobiales family: methanomicrobiaceae genus: methanogeniumromesser et al. 1981 type species methanogenium cariaciromesser et al. 1981 species m. boonei m. cariaci m. frigidum m. marinum m. organophilum description and habitat the species within methanogenium are coccoid in shape and gram-negatives and, like other methanogenic archaea, they produce methane from carbon dioxide, hydrogen or formate as substrates. although they occasionally have flagella, they are non-motile. they are strictly anaerobic, and can be found in marine and lake sediments that lack oxygen. phylogeny the currently accepted taxonomy is based on the list of prokaryotic names with standing in nomenclature (lpsn) and national center for biotechnology information (ncbi). 16s rrna-based ltp_01_2022 m. organophilum widdel, rouviere & wolfe 1989 m. cariaci widdel, rouviere & wolfe 1989 m. frigidum franzmann et al. 1997 m. marinum chong et al. 2003