Methylococcus capsulatus

Species of bacterium

Methylococcus capsulatus is an obligately methanotrophic gram negative, non motile coccoid bacterium. M. capsulatus are thermotolerant; their cells are encapsulated and tend to have a diplococcoid shape. The cell wall is composed of three layers: outer membrane, peptidoglycan layer, and inner membrane. There are extensive intracytoplasmic membranes that are believed to be formed by invaginations of the inner cell membrane. More of these intracytoplasmic membranes are produced when M. capsulatus is grown at a high copper to biomass ratio. In addition to methane, M. capsulatus is able to oxidize some organic hydrogen containing compounds such as methanol. It has been used commercially to produce animal feed from natural gas.

M. capsulatus has also been demonstrated to be thermotolerant – that is, it can grow well up to 50 °C, though its optimum growth temperature is 37 °C. In addition, M. capsulatus can live in conditions in which there is little molecular oxygen available. To produce the bacterial protein derived from the methane oxidation process, M. capsulatus must be put into an aerobic fermentation chamber otherwise known as a loop fermenter. M. capsulatus utilizes 2m3 of natural gas per kilogram of dry biomass produced. A culture of heterogenic bacteria should be added to encourage a continuous system in the loop fermenter. Natural gas contains methane, ethane, and propane and needs the following bacterium to metabolize each compound: Methylococcus capsulatus, Brevibacillus agri, and Aneurinibacillus. in Tjeldbergodden, Norway. The plant was shut down in 2006 because it could not sustain operations due to the product's low prices, it had not yet been approved by the EU,

In 2016 Calysta, an American biotech company, opened a plant in Teesside, UK, to produce up to 100 tons of fish feed a year from natural gas using M. capsulatus. The company also announced plans to build a similar plant in Memphis, Tennessee Another company, Unibio, also opened a plant to produce animal feed from natural gas in 2016 with a capacity of 80 tons per year using M. capsulatus in Kalundborg, Denmark. In 2018 a licensee of Unibio constructed an industrial scale plant in Ivangorod, Russia close to the border of Estonia. The plant has a capacity of 6,000 tonnes of protein per year.