cellular organisms; Archaea; Euryarchaeota; Methanomicrobia; unclassified Methanomicrobia; Methanomassiliicoccus
NCBI: Taxonomy 
Description and Significance
Methanomassiliicoccus luminyensis is an anaerobic, gram positive, coccus-shaped euryarchaeote. Strain B10 grows optimally at a pH of 7.6, temperature of 37˚C, and salinity of 1% NaCl. 2 No growth was recorded below 25ºC or above 45ºC. Yeast extract and selenite-tungstate are required for growth. 1 The closest cultivated phylogenetic relative to M. luminyensis is placed in the Thermoplasmatales order. Though Strain B10 and Thermoplasmatales have an 83% 16S rRNA sequence match, the growth requirements and ecological niche of M. luminyesis make it very unlike the thermoacidophilic, sulfur-reducing, Thermoplasmatales extremophiles.
Strain B10 has an unusually large genome compared to other methanogenic archea. M. luminyensis has a single circular genome containing 2,613 ORF's and a G-C content of 60.5%. 2 Strain B10 shares sequence similarities (between 98.0% and 99.0%) with other uncultured methanogenic archaea isolated from animal digestive tracts. 1
Cell Structure, Metabolism and Life Cycle
M. luminyensis is a methanogenic archaea, using hydrogen as the electron donor for methanol reduction. Despite this, strain B10 is unable to grow with methanol and hydrogen as sole carbon and electron sources. Strain B10 is non-motile with a cellular diameter of 850 nm. M. luminyensis has a double-layer cell membrane: the outer layer is thin and electron-rich, while the inner layer is thick and transparent. 1
Ecology and Pathogenesis
M. luminyensis strain B10 was first isolated from a human stool sample collected from an elderly man in Marseille, France.
Strain B10 has been isolated from stool samples in hundreds of women and men or various ages. The methanogen to which it is most closely related is a bacterium within the Methanobacteriales order, which may be evidence of horizontal gene transfer. 1
1 Dridi B., et al. (2012), Methanomassiliicoccus luminyensis gen. nov., sp. nov., a methanogenic archaeon isolated from human faeces, Unite de Recherche sur les Maladies Infectieuses et Tropicales Emergentes, Aix-Marseille-Universite, Marseille, France. International Journal of Systemic and Evolutionary Microbiology.
2 Gorlas A, Robert C, Gimenez G, Drancourt M, Raoult D. 2012. Complete Genome Sequence of Methanomassiliicoccus luminyensis, the Largest Genome of a Human-Associated Archaea Species. Journal of Bacteriology [Internet]. [cited 2012 May 31] 194(17). Available from: http://jb.asm.org/content/194/17/4745
Page authored by Melisa A. Bailey and Sarah M. Hughes, students of Prof. Jay Lennon at Michigan State University.
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