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MethylocystisRANK: GenusTAXONOMY: cellular organisms -> Bacteria -> Proteobacteria -> Alphaproteobacteria -> Rhizobiales -> Methylocystaceae -> Methylocystis OVERVIEW: Cells are small, rod-like to reniform in shape, 0.3–0.5 × 0.5–1.5 µm, usually arranged singly. Reproduce by binary division. Nonmotile. Cells contain type II intracytoplasmic membranes, which are arranged as multiple layers along the periphery of the cell wall. May form cylindrical spinae. Cells may contain a desiccation-resistant lipoidal cyst resting stage. Form inclusions of poly-β-hydroxybutyrate. Aerobic, possessing a strictly respiratory type of metabolism with oxygen as the terminal electron acceptor. Obligately methanotrophic, utilizing only methane and methanol as sole carbon and energy sources. C2+ and other C1 compounds are not utilized. Fixes formaldehyde for cell carbon via the serine pathway. Enzymes for the Benson-Calvin cycle pathway are absent and the tricarboxylic acid pathway is complete. Fixes atmospheric nitrogen. Mesophilic, neutrophilic, and nonhalophilic ecophysiology with optimal growth at about 25–30°C and pH 7.0. Major habitats include rice paddy soils, sewage, and freshwater sediments. Primary fatty acids are C18:1 ω8c and C18:1 ω7c. Primary quinone is ubiquinone-8 (Q-8). Member of the family Methylocystaceae in the Alphaproteobacteria.The mol% G + C of the DNA is: 61–67 (Tm).Type species: Methylocystis parvus |