Hyperthermus butylicus
Classification
Higher order taxa
Domain: Archaea
Phylum: Crenarchaeota
Class: Thermoprotei
Order: Desulfurococcales
Family: Pyrodictiaceae
Species
Hyperthermus butylicus
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NCBI: Taxonomy Genome |
Description and significance
Hyperthermus butylicus is under Archaeal kingdom Crenarchaeota. This aquatic anaerobe is found near the coast of the island of São Miguel, Azores, Portugal. Found in temperatures as high as 112C°, H. butylicus has a broad temperature optimum of 95 to 107C°. Thermophilic archaebacteria uses H2S formation only as an accessory energy source. Its main mode of energy is fermentation.
H. butylicus carries superoxide reductase and peroxyredoxin that removes superoxides without producing O2. Superoxides are harmful to organisms due to their free radical state. The removal of superoxides without making O2 keeps the electric gradient of the inside relatively negative compared to the outside.
There is no insertion sequence elements (IS), but there are two transposase gene fragments. Transposase genes encode proteins that move IS. One integrase gene is present, but no att sites were detected. The lack of IS, inteins, and introns suggests that the structure of H. butylicus genome is sound, and its environment is relatively constant with no real competition.
Genome structure
The genome of the Hyperthermus butylicus was sequenced and mapped using the environmental shotgun sequencing, or ESS. Instead of relying on physical appearance, this method yields phylotyping of organisms with similar rRNA sequences. The sequence of rRNA genes are present in all organisms.
H. butylicus has a single circular chromosome of 1,667,163bp with 53.7% G-C content. Out of 1672 genes annotated, 1602 are specific to protein coding. H. butylicus shares many genes that encode for proteins with other hyperthermophiles such as A. pernix and P. aerophilum.
H. butylicus contains a high percentage of codons that are responsible for the charged amino acids. Consequently, the surface proteins hold a lot of charged residues, but little non-polar residues.
Consistent with its environment, no gene coding for UV excision repair pathways was found.
Cell structure and metabolism
Hyperthermus butylicus resembles the shape of Sulfolobus. They form irregular spheres with flat surfaces. Pili are found on the surface. Vacuoles are also found below the S layer.
H. butylicus has several ways to harvest energy. It utilizes sulfur reducing enzymes such as hydrogenase to harvest energy by reducing elemental sulfur to H2S. The addition of elementary sulfur and H2 significantly helped the growth and formation of H2S. Sulfur reduction is an important way to make energy for H. butylicus. The functional protein complexes that are bound to the surface of membranes catalyze sulfur reduction to H2S.
It also uses peptide mixtures as carbon source, but cannot use amino acid mixtures, synthetic peptides, or undigested protein. No chemolithoautotrophic growth was found without the peptide mixtures as carbon source. In absence of the elementary sulfur and H2, it acquired nitrogen from NH4+ ions.
H. butylicus is the first archaebacterium to have its fermentation products identified. Fermentation occurs with and without the presence of elementary sulfur and H2. Fermentation products include CO2, 1-butanol, acetic acid, phenylacetic acid and a trace of hydroxyphenyl acetic acid.
Ecology
Samples were taken near the coast of the island of São Miguel, Azores. Hyperthermus butylicus was popular under 40cm under sand along the gas vents that release steam, CO2, and some H2S. The pH of the environment was about 7 and salt optimum of 17g of NaCl per liter.
H. butylicus has a broad temperature optimum of 95 to 107C°. It can survive temperature as high as 108C°, although it is often found in sources at 112 C°. It goes through genetic changes to assimilate into higher temperatures.
Pathology
There are no known pathogen diseases that link to H. butylicus. There is no evidence for the presence of integrated crenarchaeal viruses
References
Edited by Jeff Kwak of Rachel Larsen and Kit Pogliano
Edited KMG
