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 121 °C (250 °F), hence its name.
[1][2] Strain 121 is biostatic at 130 °C (266 °F), so while the archaeon is unable to reproduce until it has been transferred to a cooler medium, it remains viable at temperatures up to 131 °C (268 °F).
[1] Strain 121 metabolizes by reducing iron oxide (Fe(III)), a molecule that is abundant within the sediment in hydrothermal vents.
[1] Prior to the 2003 discovery of Strain 121, a fifteen-minute exposure to autoclave temperatures was believed to kill all living organisms.
[3] It may very well be the case that the true upper limit lies somewhere in the vicinity of 140 to 150 °C (284 to 302 °F), the temperature range where molecular repair and resynthesis becomes unsustainable.