In taxonomy

Alpha taxonomy

Alpha taxonomy is the discipline concerned with finding, describing and naming species of living or fossil organisms. This field is supported by institutions holding collections of these organisms, with relevant data, carefully curated: such institutes include natural history museums, herbaria and...

, Pyrobaculum is a genus of the Thermoproteaceae

Thermoproteaceae

In taxonomy, the Thermoproteaceae are a family of the Thermoproteales.-External links:...

.

Description and Significance

As its latin name, Pyrobaculum (the "fire stick") suggests, the archaeon is rod-shaped and isolated from locations with high temperatures. It is Gram-negative and its cells are surrounded by an S-layer of protein subunits.

P. aerophilum is a hyperthermophilic and metabolically versatile organism. Different from other hyperthermophiles, it can live in the presence of oxygen and grows efficiently in microaerobic conditions.

Genome Structure

So far, only the genome of one species, P. aerophilum, has been sequenced. Its circular genome sequence is 2,222,430 Bp in length and contains 2605 protein-encoding sequences (CDS)

Cell Structure and Metabolism

Under anaerobic conditions, the archaeon reduces nitrate to molecular nitrogen via the denitrification pathway. Most species grow either chemolithoautotrophically by sulfur reduction or organotrophically by sulfur respiration or by fermentation. Cells are rod-shaped with almost rectangular ends and are about 1.5-8 * 0.5-0.6 µm. Pyrobaculum is motile because of peritrichous or bipolar polytrichous flagellation, and its colonies are round and grey to greenish black. The species are either faculatively aerobic or strictly anaerobic. The growth was observed on yeast extract, peptone, extract of meat, but not on galactose

Galactose

Galactose , sometimes abbreviated Gal, is a type of sugar that is less sweet than glucose. It is a C-4 epimer of glucose....

, glucose

Glucose

Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...

, maltose

Maltose

Maltose , or malt sugar, is a disaccharide formed from two units of glucose joined with an αbond, formed from a condensation reaction. The isomer "isomaltose" has two glucose molecules linked through an α bond. Maltose is the second member of an important biochemical series of glucose chains....

, starch glycogen, ethanol

Ethanol

Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...

, methanol

Methanol

Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with the formula CH3OH . It is the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a distinctive odor very similar to, but slightly sweeter than, ethanol...

, formamide

Formamide

Formamide, also known as methanamide, is an amide derived from formic acid. It is a clear liquid which is miscible with water and has an ammonia-like odor. It is used primarily for manufacturing sulfa drugs and synthesizing vitamins and as a softener for paper and fiber...

, formate

Formate

Formate or methanoate is the ion CHOO− or HCOO− . It is the simplest carboxylate anion. It is produced in large amounts in the hepatic mitochondria of embryonic cells and in cancer cells by the folate cycle Formate or methanoate is the ion CHOO− or HCOO− (formic acid minus one hydrogen ion). It...

, malate

Malate

Malate is the ionized form of malic acid. It is an important chemical compound in biochemistry. In the C4 carbon fixation process, malate is a source of CO2 in the Calvin cycle....

, propionate

Propionate

The propanoate or propionate ion is C2H5COO− .A propanoic or propionic compound is a salt or ester of propanoic acid....

, lactate

Lactate

Lactate may refer to:*The act of lactation*The conjugate base of lactic acid...

, acetate

Acetate

An acetate is a derivative of acetic acid. This term includes salts and esters, as well as the anion found in solution. Most of the approximately 5 billion kilograms of acetic acid produced annually in industry are used in the production of acetates, which usually take the form of polymers. In...

, and casamino acids

Casamino acids

Casamino acids is a mixture of amino acids and some very small peptides obtained from acid hydrolysis of casein It is typically used in microbial growth media...

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The first of the Pyrobaculum species to be genetically sequenced, P. aerophilum (rod-shaped, 3-8 * 0.6 µm), has a rare characteristic for an archaeon because it is capable of aerobic respiration (aerophilum = "air-loving"). This is evident from the fact that the archaeon grew only in the presence of oxygen when nitrate was absent. It produces colonies that are round and greyish yellow. It utilizes both organic (maximal cell densities were observed with complex organics such as yeast extract, meat extract, tryptone, and peptone as substrates) and inorganic compounds during aerobic and anaerobic respiration. Also, use of elemental sulphur for growth was observed. Further, P. aerophilum grows between 75 and 104°C with an optimal growth temperatrue at 100°C.

Ecology

To this date, the strains of Pyrobaculum have been isolated from neutral to slightly alkaline boiling solfataric waters and shallow marine hydrothermal systems. P. aerophilum was isolated from a boiling marine water hole at Maronti Beach, Ischia, Italy. Further studies show that P. aerophilum grows under strictly anaerobic conditions with nitrate as the electron acceptor.

External links