The newly isolated hyperthermophilic archaeal strain 121
grows slowly at 121 8C and even survives short periods at
130 8C. This is another organism that grows best at
temperatures well in excess of 100 8C! We should not be
astonished so much by the numerical increments but by
the biochemical implications of this fact, and we should be
excited by the scope provided by this and similar
organisms to further our understanding of the evolution
and adaptation of molecular structures and systems.
And what about the upper limit of life? It appears
improbable that the end-point of this search is represented
by strain 121. The consensus view is that the true upper
limit, where the energetic burden imposed by molecular
repair and resynthesis becomes unsustainable, will
probably lie in the region of 140–150 8C