Life above 100°C

Until  recently  the  highest  reported  temperature  for  procaryotic growth was 105°C. It seemed that the upper temperature limit Ufor life was about 100°C, the boiling point of water. Now thermophilic procaryotes have been reported growing in sulfide chimneys or “black  smokers,” located  along  rifts  and  ridges on  the ocean  floor, that spew sulfide-rich superheated vent water with temperatures above 350°C . 

 

Evidence has been presented  that  these microbes can grow and reproduce at 113°C. The pressure present in their habitat is suf ficient to keep water liquid (at 265 atm; seawater doesn’t boil until 460°C). The  implications of  this discovery are many. The proteins, membranes, and nucleic acids of these procaryotes are remarkably tempera- ture  stable  and provide  ideal  subjects  for  studying  the ways  in which macromolecules and membranes are stabilized. In the future it may be possible to design enzymes that can operate at very high temperatures. Some  thermostable enzymes  from  these organisms have  important  industrial and scientific uses. For example, the Taq polymerase from the thermophile Thermus aquaticus is used extensively  in  the polymerase chain reaction.