Example Isolate Description


Example

Methanocaldococcus jannaschii

Methanococcus microgrsaphMethanocaldococcus (previously Methanococcus) jannaschii is a methanogenic member of the euryarchaea, and is a motile coccus with a single 'tuft' of many flagella. The organism is an obligate autotroph (as are all methanogens), reducing CO2 or CO with H2 to produce methane. Also like all other methanogens, M. jannaschii is an extreme anaerobe and is autofluorescent (fluorescing green in UV illumination). No carbon compounds other than CO2 or CO and no reductants other than H2 can be used. M. jannaschii is a complete prototroph; in other words, it can synthesis all of the vitamins, amino acids, sugars, etc, that it needs starting with inorganic material. In fact, it can even fix nitrogen from N2 gas, and can assimilate sulfur from sulfate. M. jannaschii is a thermophile, growing optimally at 80C; it was isolated from a deep sea hydrothermal vent environment. Membrane lipids are a mix of C20 and C40 ethers. The cell wall is entirely protein, and so is easily disrupted with detergent. M. jannaschii is resistant to most antibiotics tested, but in some cases this may be because the harsh media and temperature might destroy the antibiotic. It is sensitive, however, the chloramphenicol and BES (bromoethanesulfonate). The entire sequence of the genome of M. jannaschii has been determined; it was the first archaeal genome sequence available. The genome consists of 3 circular chromosomes: one large (ca. 2Mbp) chromosome containing all of the identifiable genes, and 2 small (138 and 38Kb) chromosomes that could also be considered single-copy plasmids.

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