Strain 121

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Strain 121 (Geogemma barossii) is a single-celled microbe of the domain Archaea. First discovered within a hydrothermal vent in the Northeast Pacific Ocean near the Endeavor segment of the Juan de Fuca Ridge, Strain 121 is a hyperthermophile capable of reproducing at Template:Convert, hence its name.<ref name="Kashefi, Lovely">Template:Cite journal</ref><ref>Template:Cite journal</ref> Strain 121 is biostatic at Template:Convert, so while the archaeon is unable to reproduce until it has been transferred to a cooler medium, it remains viable at temperatures up to Template:Convert.<ref name="Kashefi, Lovely" /> Strain 121 possess a coccoid shape with lophotrichous flagellation, reaching approximately 1.0 μm in diameter.<ref name="Kashefi, Lovely" /> Strain 121 metabolizes by reducing iron oxide (Fe(III)), a molecule that is abundant within the sediment in hydrothermal vents.<ref name="Kashefi, Lovely" />

The maximum growth temperature of strain 121 is 8 °C higher than the previous record holder, Pyrolobus fumarii (T_max = 113 °C).<ref name="Cowan">Template:Cite journal</ref> At the time of its discovery, Strain 121 was the only known form of life that could tolerate such high temperatures, but in 2008 Methanopyrus kandleri was discovered to be able to reproduce at temperatures as high as 122 °C. Autoclaves, which are an important tool in sterilization, operate at temperatures of Template:Convert, marking Strain 121 a particularly notable discovery.<ref name="Kashefi, Lovely" /> Prior to the 2003 discovery of Strain 121, a fifteen-minute exposure to autoclave temperatures was believed to kill all living organisms.<ref name="Kashefi, Lovely" /> However, as Strain 121 is unable to reproduce at temperatures below Template:Convert, it cannot infect humans, who have an average body temperature of approximately Template:Convert.<ref name="Kashefi, Lovely" /><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

It appears highly improbable that Strain 121 marks the upper limit of viable growth temperature.<ref name="Cowan" /> It may very well be the case that the true upper limit lies somewhere in the vicinity of Template:Convert, the temperature range where molecular repair and resynthesis becomes unsustainable.<ref name="Cowan" />

See also

• Methanopyrus kandleri (Strain 116)

References

• Template:Cite journal
• Cowan, D. (2004). “The Upper Temperature for Life – Where Do We Draw the Line?” Trends in Microbiology (Regular Ed.), vol. 12, no. 2, Elsevier Ltd, pp. 58–60, https://doi.org/10.1016/j.tim.2003.12.002.

External links

• Guardian News
• Science Daily article
• NSF "Microbe from Depths Takes Life to Hottest Known Limit"
• How Hot is Too Hot for Earth-Style Life?