Taxonomy Archaea, Euryarchaeota, Methanococci, Methanococcales, Methanocaldococcaceae, Methanocaldococus, infernus
Species NCBI: Taxonomy Methanocaldococcus Infernus
Description and significance
Methanocaldococcus infernus is part of the domain of Archaea, and it is an extreme thermophile. This microbe can grow between 55-90°C with optimal growth at 85°C and optimum pH of 6.5. This microbe is non-pathogenic and it was the first archaean genome to be completely sequenced and it revealed many eukaryote- like elements (3). It has been found to be able to fix N2 to NH3 at a temperature of up to 92°C which is 28°C higher than the current upper temperature limit of biological nitrogen fixation. This finding of the increase of temperature limit of nitrogen fixation could reveal a broader range of conditions for life in the sub sea floor biosphere and other nitrogen-limited ecosystems than previously estimated (6).
Methanocaldococcus infernus is closely related to Methanocaldococcus jannaschii strain JAL-1T. Its 16s gene is 99% similar to the non-nitrogen fixing Methanocaldococcus jannaschii strain (3). The genome consists of circular chromosomes and it was sequenced using 16s small ribosomal subunit gene sequencing analysis. The genome is 1,328,194 base pairs in length with a gene count of 1513 and GC content of 33.62% (5).
Cell and colony structure This microbe exhibits a coccoid shape and ranges from 1-3μ in diameter. The cells are motile and heavily flagellated. Motility exhibited in tumbling motility by means of at least three tufts of flagella with each tuft containing a high number of flagella (2). Cells possess a typical archaeal cell envelope consisting of cytoplasmic membrane and single surface layer (S-layer). Experimentally the cells are found in pale yellow colonies on solidified medium when incubated in anaerobic jar at 75°C (1).
This microbe is anaerobic and a methanogen, which is a group of microorganisms that produce methane as a metabolic by-product in anoxic environments. It uses H2 and CO2 as energy and carbon sources to produce methane. Also has the ability to fix N2 to NH3 (3).
Samples of this microbe have been taken from deep-sea hydrothermal chimneys on the Mid-Atlantic ridge at a depth of 3000m (4)
Methanocaldococcus infernus is non-pathogenic. Growth is inhibited by choloramphenicol (75 pg ml-l) and rifampicin (50 pg ml-l) but not my streptomycin, penicillin G, kanamycin and ampicillin (all at 200 pg ml-l) (1)
(1.) “Methanocaldococcus infernus ME”. BacMap.11 Feb, 2013
(2.) Shneider, Kevin, Katherine Pollard, Andy Pohl, Todd Lowe, and Robert Baertsch. “Methanocaldococus Infernus ME Genome Browser Gateway. Genome Bioinformatics Group of UC Santa Cruz. Feb 11, 2013.
(3.) “KEGG GENOME: Methanocaldococcus Infernus.” KEGG GENOME: Methanocaldococcus Infernus. 11 Feb, 2013.
(4.) Jeanthon, C., S.L’Haridon, A.L. Reysenbach, Marc Vernet, P. Messner, U.B. Sleytr, and D, Prieur. “ International Journal of Systematic and Evolutionary Microbiology” Methanocaldococcus infernus sp. Nov., a Novel Hyperthermophilic Lithotrophic Methanogen Isolated from a Deep Sea hydrothermal vent.
(5.) "Methanocaldococcus Infernus ME - Info." Methanocaldococcus Infernus ME - Info. 14 Mar. 2013.
(6.) Mehta, M.P and J.A. Baross. “Nitrogen Fixation at 92C by a hydrothermal vent archaeon.” Science 314.5806 (2006): 1783-786.
Edited by Lauren O’Neil of Dr. Lisa R. Moore, University of Southern Maine, Department of Biological Sciences, http://www.usm.maine.edu/bio