Strain 121 (''Geogemma barossii'') is a single-
celled microbe
A microorganism, or microbe, is an organism of microscopic size, which may exist in its single-celled form or as a colony of cells. The possible existence of unseen microbial life was suspected from antiquity, with an early attestation in ...
of the
domain Archaea
Archaea ( ) is a Domain (biology), domain of organisms. Traditionally, Archaea only included its Prokaryote, prokaryotic members, but this has since been found to be paraphyletic, as eukaryotes are known to have evolved from archaea. Even thou ...
. 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
A hyperthermophile is an organism that thrives in extremely hot environments—from 60 °C (140 °F) upward. An optimal temperature for the existence of hyperthermophiles is often above 80 °C (176 °F). Hyperthermophiles are of ...
capable of reproducing at , hence its name.
Strain 121 is
biostatic at , so while the archaeon is unable to reproduce until it has been transferred to a cooler medium, it remains viable at temperatures up to .
Strain 121 possess a coccoid shape with lophotrichous flagellation, reaching approximately 1.0 μm in diameter.
Strain 121 metabolizes by
reducing iron oxide
An iron oxide is a chemical compound composed of iron and oxygen. Several iron oxides are recognized. Often they are non-stoichiometric. Ferric oxyhydroxides are a related class of compounds, perhaps the best known of which is rust.
Iron ...
(Fe(III)), a molecule that is abundant within the sediment in hydrothermal vents.
The maximum growth temperature of strain 121 is 8 °C higher than the previous record holder, ''
Pyrolobus fumarii'' (T
max =
113
°C).
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.
Autoclave
An autoclave is a machine used to carry out industrial and scientific processes requiring elevated temperature and pressure in relation to ambient pressure and/or temperature. Autoclaves are used before surgical procedures to perform steriliza ...
s, which are an important tool in
sterilization, operate at temperatures of , marking Strain 121 a particularly notable discovery.
Prior to the 2003 discovery of Strain 121, a
fifteen-minute exposure to autoclave temperatures was believed to kill all living organisms.
However, as Strain 121 is unable to reproduce at temperatures below , it cannot infect humans, who have an average body temperature of approximately .
It appears highly improbable that Strain 121 marks the upper limit of viable growth temperature.
It may very well be the case that the true upper limit lies somewhere in the vicinity of , the temperature range where molecular repair and resynthesis becomes unsustainable.
See also
* ''
Methanopyrus kandleri'' (Strain 116)
References
*
*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
"Microbe from Depths Takes Life to Hottest Known Limit"
How Hot is Too Hot for Earth-Style Life?
{{Taxonbar, from=Q3267859
Thermoproteota
Thermophiles
Archaea described in the 21st century
Undescribed species
fr:Pyrolobus#Historique