"Aquifex aeolicus"
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Species: | A. aeolicus
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"Aquifex aeolicus" |
"Aquifex aeolicus" is a chemolithoautotrophic, Gram-negative, motile, hyperthermophilic bacterium.[1] "A. aeolicus" is generally rod-shaped with an approximate length of 2.0-6.0
Microbiological Characteristics[edit]
Morphology
Mature "A. aeolicus" cells are typically rod-shaped bacterium with an approximate length of 2.0-6.0
Metabolism
As an autotroph, "A. aeolicus" has the ability to obtain all necessary carbon by fixing CO2 from the environment and utilizes molecular hydrogen as an electron/energy source.[1][5] Additionally, this bacterium utilizes a reductive TCA cycleas it provides the substrates of many bio synthetic pathways. The "A. aeolicus" genome contains encoding genes that together could constituent the TCA pathway: fumarate reductase, fumarate hydratase, isocitrate dehydrogenase, malate dehydrogenase, ferredoxin oxidoreductase, succinate-CoA ligase, aconitase and citratesynthase.[1] Moreover, this bacterium uses oxygen, hydrogen, and mineral salts as its primary energy sources. "A. aeolicus" can also reduce nitrogen and sulfur.[5]
Regarding its growth under microaerophilic conditions, Aquifex species have been observed to grow in oxygen concentrations as long as 7.5ppm.[6] It is hypothesized that this is possible because 1) their oxygen-respiration system was already highly developed before the advent of oxygenic photosynthesis, 2) the Aquifex lineage came to life after there was a rise in atmospheric oxygen, or 3) oxygen respiration was developed, and then transferred among different bacterial lineages, such as Aquifex.[1] In response to oxidative stress, "A. aeolicus" possesses protective enzymes such as superoxide and peroxide to counter harmful oxygen species.[3]
Habitat[edit]
"A. aeolicus" was originally isolated from underwater volcanic vents near the Aeolic Islands (north of Sicily) and has also been isolated from the hot springs in Yellowstone.[5] As a hyperthermophile, "A. aeolicus" can survive up to 95 °C with a temperature optima of 85 °C[2] with a pH optima of 8.0, ranging from 6.8 to 9.0.[2]
Genomic Properties[edit]
"Aquifex aeolicus" is the first thermophilic bacterium to have its entire genome sequenced.[2] Comparison of the "Aquifex aeolicus" genome to other organisms showed that around 16% of its genes originated from the Archaea domain. It is most closely related to the hydrogen-oxidizing bacterium, Aquifex pyrophilus, and its close relative, Hydrogenobacter thermophilus.[6]
The genome of "A. aeolicus" has been successfully mapped,[1] but was noted to be only one-third the size of the E. coli genome. The genome of "A. aeolicus" is densely packed while no introns or protein splicing elements were found.[3] It possesses a circular chromosome with 1,551,335 bp and has a G+C content of 43.4%, and contains 1,796 genes.[3] It also contains genes potentially coding for three distinct [NiFe] hydrogenases, however, it is thought that the Aquifex hydrogenases I and II function in energy conservation, where as hydrogenase III is more likely required for CO2fixation.[2] Additionally, during sequencing, a single extra chromosomal element (ECE) was identified,[1] suggesting evidence of genetic exchange between the "A. aeolicus" chromosome and the ECE.
Industrial Applications[edit]
Multiple enzymes have been identified for potential future use due to their high stability and capacity to oxidize molecular hydrogen, producing byproducts of heat and water.[2][5] A key enzyme of note is Hydrogenase I which was used to study the relationship of enzymes and electrodes during the development of H2-fed, energy-generating biofuel cells.[2] Researchers have explored the use of another extremely resistant enzyme known as lumazine synthase. The cage-forming enzyme has been explored as potential drug delivery nano carrier as it was engineered to encapsulate other molecules.[2]
References[edit]
- ^ a b c d e f g h i j Huber, R.; Swanson, R.; Deckert, G.; Warren, P.; Gaasterland, T.; Young, W.; Lenox, A.; Graham, D. (1998). "The complete genome of the hyperthermophilic bacterium Aquifex aeolicus". Nature. 392 (6674): 353–8. Bibcode:1998Natur.392..353D. doi:10.1038/32831. PMID 9537320.
- ^ a b c d e f g h Guiral, Marianne; Giudici-Orticoni, Marie-Thérèse (2021-01-01). "Microbe Profile: Aquifex aeolicus: an extreme heat-loving bacterium that feeds on gases and inorganic chemicals". Microbiology. 167 (1). doi:10.1099/mic.0.001010. ISSN 1350-0872. PMID 33350903. S2CID 229351588.
- ^ a b c d Deckert, Gerard; Warren, Patrick V.; Gaasterland, Terry; Young, William G.; Lenox, Anna L.; Graham, David E.; Overbeek, Ross; Snead, Marjory A.; Keller, Martin; Aujay, Monette; Huber, Robert (March 1998). "The complete genome of the hyperthermophilic bacterium Aquifex aeolicus". Nature. 392 (6674): 353–358. Bibcode:1998Natur.392..353D. doi:10.1038/32831. ISSN 1476-4687. PMID 9537320. S2CID 4413967.
- ^ a b c Guiral, M; Prunetti, L; Aussignargues, C; Ciaccafava, A; Infossi, P; Ilbert, M; Lojou, E; Giudici-Orticoni, M. T. (2012). "The Hyperthermophilic Bacterium Aquifex aeolicus". The hyperthermophilic bacterium Aquifex aeolicus: From respiratory pathways to extremely resistant enzymes and biotechnological applications. Advances in Microbial Physiology. Vol. 61. pp. 125–94. doi:10.1016/B978-0-12-394423-8.00004-4. ISBN 9780123944238. PMID 23046953.
- ^ a b c d e Gupta, Radhey S.; Lali, Ricky (2013-09-01). "Molecular signatures for the phylum Aquificae and its different clades: proposal for division of the phylum Aquificae into the emended order Aquificales, containing the families Aquificaceae and Hydrogenothermaceae, and a new order Desulfurobacteriales ord. nov., containing the family Desulfurobacteriaceae". Antonie van Leeuwenhoek. 104 (3): 349–368. doi:10.1007/s10482-013-9957-6. ISSN 1572-9699. PMID 23812969. S2CID 254232862.
- ^ a b Reysenbach, L.; Wickham, G. S.; Pace, N. R. (1994). "Phylogenetic analysis of the hyperthermophilic pink filament community in Octopus Spring, Yellowstone National Park". Applied and Environmental Microbiology. 60 (6): 2113–2119. doi:10.1128/AEM.60.6.2113-2119.1994. PMC 201609. PMID 7518219.