marine solar vent
Could you please name and describe five euryarchaeotes from at least three different orders?
Euryarchaeota (Greek for “broad old quality”) are a phylum of the Archaea. The Euryarchaeota include the methanogens, which produce methane and are often found in intestines, the halobacteria, which survive extreme concentrations of salt, and some extremely thermophilic aerobes and anaerobes. They are separated from the other archaeans based mainly on rRNA sequences. Five species are:
(1) Archaeoglobus fulgidus (Class Archaeoglobi, Order Archaeoglobales, Family Archaeoglobaceae; Stetter et al., 198) is a hyperthermophile isolated from hydrothermal vents. Archaeoglobus can also be found in high-temperature oil fields, where they may contribute to oil field souring. Optimal growth of these organisms occurs at approximately 83ºC. Metabolically, Archaeoglobus are sulfate-reducing Archaea, coupling to the reduction of sulfate (to sulfide) to the oxidation of many different organic carbon sources, including complex polymers. Archaeoglobus can also live chemolithoautotrophically by coupling the oxidation of thiosulfate to the reduction of hydrogen gas. Archaeoglobus are the only organisms other than the traditional sulfate-reducing bacteria capable of the reduction of sulfate. Intriguingly, the completion of the complete A. fulgidus genome sequence revealed the presence of a nearly complete set of genes for methanogenesis. The function of these genes in A. fulgidus remains unknown, although the lack of the enzyme methyl-CoM reductase does not allow for methanogenesis to occur by a mechanism similar to that found in other methanogens.
(2) Halobacterium salinarum (“Salt” or “Ocean Bacterium”) (Class Halobacteria, Order Halobacteriales, Family Halobacteriaceae) is an extremely halophilic marine gram-negative obligate aerobic archaeon. Despite its name, this microorganisms is not a bacterium, but rather a member of the Domain Archaea. It is found in salted fish, hides, hypersaline lakes, and salterns. Salterns are enclosed basins filled with seawater that are left to evaporate, yielding solar sea salt. As these salterns reach the minimum salinity limits for extreme halophiles, their waters become purple or reddish color due to the algal bloom of halophilic Archaea. H. salinarum has also been found in high-salt food such as salt pork, marine fish, and sausages. To survive in extremely salty environments, this archaeon—as with other halophilic Archaean species—utilizes compatible solutes (in particular potassium chloride) that acts as a sort of antifreeze/coolant to keep the cell metabolism functioning. H. salinarum is an obligate aerobe. It reproduces by binary fission. It does not form spores. Most are not motile. Halobacterium salinarum is responsible for the bright pink or red appearance of the Dead Sea and other bodies of salt water. Halobacteria are single-celled, rod-shaped microorganisms that are among the most ancient forms of life and appeared on earth billions of years ago. Halobacteria are archaea that grow optimally in extremely high saline environments (up to 5.5 M NaCl). Their natural habitats are salt evaporation ponds and natural salt lakes and other environments where the salt concentration comes close to saturation. Occasionally they are isolated from hides and from the surfaces of heavily salted foods. Halobacterium sp. NRC-1 is as easy to culture as E. coli and serves as an excellent model system for archaeal genetics and functional genomics. Whole proteome comparisons show the definite archaeal nature of this halophile with additional similarities to the Gram-positive Bacillus subtilis and other bacteria. Whole genome sequences are available for two strains of H. salinarum, NRC-1 and R1.
(3) Methanobrevibacter smithii (Class Methanobacteria, Order Methanobacteriales, Family Methanobacteriaceae) is the dominant archaean in the human gut. It is important for the efficient digestion of polysaccharides (complex sugars) because it consumes end products of bacterial fermentation.
(4) Pyrococcus furiosus (Class Thermococci, Order Thermococcales, Family Thermococcaceae) is an extremophilic species of Archaea. It is notable for having an optimum growth temperature of 100°C (a temperature which would destroy most living organisms), and for being one of the few organisms identified as possessing enzymes containing tungsten, an element rarely found in biological molecules.
(5) Thermoplasma acidophilum (Class Thermoplasmata, Order Thermoplasmatales, Family Thermoplasmataceae) thrives in acidic and high-temperature environments, and is a facultative anaerobe, respiring using sulfur and organic carbon. They do not contain a cell wall, but instead contain a unique membrane composed mainly of a tetraether lipoglycan containing atypical archaeal tetraether lipid attached to a glucose- and mannose-containing oligosaccharide. This lipoglycan is presumably responsible for the acid and thermal stability of the Thermoplasma membrane. T. acidophilum was originally isolated from a self-heating coal refuse pile, at pH 2 and 59 °C. They are highly flagellated. The genomes for both T. acidophilum and T. volcanicum have been sequenced. T. acidophilum is a thermoacidophilic archaeon that was isolated from a coal refuse pile. T. acidophilum grows optimally at 56 ?, pH 1.8 and size of a cell is about 1 ?m. T. acidophilum lacks a cell wall and the cell membrane is exposed directly outside. T. acidophilum shows various cell shapes depending upon growth conditions and stages. Though there is no cell wall, it shows various forms.