The upper temperature for life – where do we draw the line?

Abstract

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