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Aquifex pyrophilus
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<h2 id="etymology">Etymology</h2> <p><i>Aquifex pyrophilus</i> has a name that references its <a href="/facts/Respiration_(physiology)/KKWAJIbd">respiration</a> and its <a href="/facts/Habitat/zo1DN2gA">habitat</a>. The name "Aquifex" means "water-maker" in <a href="/facts/Latin/pM3Kge85">Latin</a>. The name was assigned to <i>A. pyrophilus</i> because it typically uses <a href="/facts/Oxygen/acyn6o8r">oxygen</a> as its <a href="/facts/Respiration_(physiology)/KKWAJIbd">respiration</a> and <a href="/facts/Water/0lkXnJPK">water</a> as a <a href="/facts/By-product/qDosnqoD">byproduct</a>.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> The name "Pyrophilus" can be broken down into "Pyro" and "Philus". "Pyro" is Latin for fire, heat, or high temperature and "Philus" is a Latin word for "loving". Therefore the term "pyrophilus" can be interpreted as "heat loving" which refers to the <a href="/facts/Habitat/zo1DN2gA">habitat</a> <i>A. pyrophilus</i> is typically found in. </p> <h2 id="habitat">Habitat</h2> <p>The genus Aquifex is a contains some of the most thermophilic bacterium of all known bacteria. <i>A. pyrophilus</i> is an aquatic microbe that is typically found near <a href="/facts/Volcano/c2M5upml">underwater volcanoes</a>, <a href="/facts/Hydrothermal_vent/0xPqNUkY">marine hydrothermal vents</a>, and/or <a href="/facts/Hot_spring/YrzFykH1">hot springs</a> where temperatures are extremely high and pressure can be immense.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> <i>A. pyrophilus</i> has shown resistance to <a href="/facts/Ultraviolet/kncBUqn5">ultraviolet light</a> and <a href="/facts/Ionizing_radiation/vw0d9GaT">ionizing radiation</a>.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> The <i>Aquifex</i> <a href="/facts/Genus/m8EFjSms">genus</a> is rather intolerable to <a href="/facts/Oxygen/acyn6o8r">oxygen</a> therefore it is only found in <a href="/facts/Hypoxia_(environmental)/VSSWPNlF">low-oxygenated environments</a>. Despite this, <i>Aquifex</i> remains one of only <a href="/facts/Cellular_respiration/kb6gpsvL">aerobic</a> bacterial <a href="/facts/Hyperthermophile/UBmwC64t">hyperthermophiles</a> known.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> Oxygen is limited near these hydrothermal vents and underwater volcanos because of the extremely high temperature and reducing power of volcanic gases like H2S. <i>A. pyrophilus</i> thrives where the oxic and <a href="/facts/Anoxic_waters/vLdveWX0">anoxic</a> zones meet in these environments because of the high availability of hydrogen and <a href="/facts/Thiosulfate/LYu0KhDu">thiosulfate</a>.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> </p><p><i>Aquifex pyrophilus</i> was discovered at <a href="/facts/Kolbeinsey_Ridge/rALUxFwp">Kolbeinsey Ridge</a>, North of <a href="/facts/Iceland/E4KGYs2j">Iceland</a> by <a href="/facts/Robert_Huber/gnazDTgn">Robert Huber</a> and <a href="/facts/Karl_Stetter/0lrCF0K2">Karl Stetter</a> in 1992.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> In Huber's and Stetter's first analysis of the bacteria, they found that <i>A. pyrophilus</i> had an optimum <a href="/facts/PH/RnSv8D7y">pH</a> of 6.8 but ranged anywhere between 5.4 and 7.5, grew at temperatures ranging from 67 °C to 95 °C with an optimum at 85 °C, and had optimal growth with a <a href="/facts/Sodium_chloride/MWcXl3Mb">NaCl</a> concentration of 3% (range of 1-5%).<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> </p><p><i>A. pyrophilus</i> is 2 to 6 micrometers long and has a diameter of around half a micrometer. It has eight polytrichously inserted flagella making it motile.<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> <i>A. pyrophilus</i> can grow singly, in pairs, and/or form large cell <a href="/facts/Biofilm/zg93x2w4">conglomerations</a>, comprising up to 100 individual cells.<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a><a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a> </p> <h2 id="metabolism">Metabolism</h2> <p><i>A. pyrophilus</i> is strictly <a href="/facts/Lithoautotroph/UxUKtfzA">chemolithoautotrophic</a>.<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a> It is capable of using <a href="/facts/Oxygen/acyn6o8r">oxygen</a> in its <a href="/facts/Respiration_(physiology)/KKWAJIbd">respiration</a>, but can also grow <a href="/facts/Anaerobic_organism/bhQnlqCq">anaerobically</a> by nitrate reduction.<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a> In <a href="/facts/Aerobic_organism/a629EQD7">aerobic</a> conditions, <i>A. pyrophilus</i> oxidizes molecular hydrogen and yields <a href="/facts/Water/0lkXnJPK">H2O</a> and <a href="/facts/ATP_synthase/5NBMxsVX">ATP</a>. Other electron donors that A. pyrophilus uses in aerobic conditions are S° and S2O32-.<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a> Byproducts include <a href="/facts/Sulfuric_acid/Wom6fymJ">sulfuric acid</a> from S° and S2O32- and <a href="/facts/Hydrogen_sulfide/UbCqjMMk">hydrogen sulfide</a> from S° and H2.<a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a> </p> <h2 id="lineage-and-phylogeny">Lineage and phylogeny</h2> <p><i>A. pyrophilus</i> has a relatively small <a href="/facts/Genome/31Sm08JT">genome</a>. Out of the known thermophile genomes, <i>A. pyrophilus</i> is the smallest.<a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a> Due to its small genome, its ability to survive in extreme heat, its ability to be resistant toward <a href="/facts/Ultraviolet/kncBUqn5">ultraviolet light</a> and <a href="/facts/Ionizing_radiation/vw0d9GaT">ionizing radiation</a>, and because of <a href="/facts/Phylogenetics/bw4rsovt">phylogenetic</a> analyses of the small-subunit 16S <a href="/facts/Ribosomal_RNA/zy5FxddY">rRNA</a> gene, <i>A. pyrophilus</i> is thought to be one of the oldest species in the bacteria domain.<a class="footnote-ref" id="fnref:18" href="#fn:18"><sup>18</sup></a><a class="footnote-ref" id="fnref:19" href="#fn:19"><sup>19</sup></a> </p><p>Investigations of the <a href="/facts/Phylogenetics/bw4rsovt">phylogenetic</a> position of <a href="/facts/Aquificota/enEmhVjX">Aquificales</a> have utilized the <a href="/facts/Concatenation/1npYg6rc">concatenated</a> <a href="/facts/Protein/Jxmagu3E">proteins</a> shared within the Aquificales order and <i>A. pyrophilus</i>.<a class="footnote-ref" id="fnref:20" href="#fn:20"><sup>20</sup></a> The results show that the Aquificales are most closely related to <a href="/facts/Thermotogota/GggLdxhs">Thermotogales</a> when observing whole-genome information.<a class="footnote-ref" id="fnref:21" href="#fn:21"><sup>21</sup></a> Additionally, Aquificales were found to be somewhat closely related to <a href="/facts/Campylobacterota/tXKmFDSc">ε-proteobacteria</a> in <a href="/facts/Phylogenetic_tree/f5vVEpeY">phylogenetic trees</a>.<a class="footnote-ref" id="fnref:22" href="#fn:22"><sup>22</sup></a> This slight ambiguity in the placement of Aquificales on the phylogenetic tree leaves room for some more research in this field. Despite this, there is overwhelming evidence that Aquificales, including <i>A. pyrophilus</i>, are some of the earliest bacteria to branch from archaea.<a class="footnote-ref" id="fnref:23" href="#fn:23"><sup>23</sup></a> This has led to hypothesis that these bacteria evolved when the <a href="/facts/Earth/HLLmDfj0">earth</a> was still hot and had a thin <a href="/facts/Atmosphere/oUpLaGRF">atmosphere</a>.<a class="footnote-ref" id="fnref:24" href="#fn:24"><sup>24</sup></a> </p> <h2 id="external-links">External links</h2> <ul><li><a href="http://bacdive.dsmz.de/strain/508">Type strain of <i>Aquifex pyrophilus</i> at Bac<i>Dive</i> - the Bacterial Diversity Metadatabase</a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>"aquifex". 2005-03-12. Archived from the original on 2005-03-12. Retrieved 2022-09-13. <a href="https://web.archive.org/web/20050312181937/http://biology.kenyon.edu/Microbial_Biorealm/bacteria/aquifex/aquifex.htm" target="_blank">https://web.archive.org/web/20050312181937/http://biology.kenyon.edu/Microbial_Biorealm/bacteria/aquifex/aquifex.htm</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Beblo, Kristina; Douki, Thierry; Schmalz, Gottfried; Rachel, Reinhard; Wirth, Reinhard; Huber, Harald; Reitz, Günther; Rettberg, Petra (2011-11-01). "Survival of thermophilic and hyperthermophilic microorganisms after exposure to UV-C, ionizing radiation and desiccation". Archives of Microbiology. 193 (11): 797–809. doi:10.1007/s00203-011-0718-5. ISSN 1432-072X. PMID 21638055. 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PMID 22844640. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3403428" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3403428</a> <a href="#fnref:20" class="footnote-back-ref">↩</a></p></li> <li id="fn:21"><p>Oshima, Kenro; Chiba, Yoko; Igarashi, Yasuo; Arai, Hiroyuki; Ishii, Masaharu (2012-07-12). "Phylogenetic Position of Aquificales Based on the Whole Genome Sequences of Six Aquificales Species". International Journal of Evolutionary Biology. 2012: 859264. doi:10.1155/2012/859264. ISSN 2090-8032. PMC 3403428. PMID 22844640. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3403428" target="_blank">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3403428</a> <a href="#fnref:21" class="footnote-back-ref">↩</a></p></li> <li id="fn:22"><p>Oshima, Kenro; Chiba, Yoko; Igarashi, Yasuo; Arai, Hiroyuki; Ishii, Masaharu (2012-07-12). "Phylogenetic Position of Aquificales Based on the Whole Genome Sequences of Six Aquificales Species". 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