Thermostable DNA polymerases

Dr Mullis understood that a decisive limit to the success of the amplification reaction was the destruction by heating of the DNA polymerase enzyme that had to continually be added during each cycle of the process since it did not endure the high temperatures of the PCR cycles. In fact, when he started experimenting in the Eighties he used a DNA polymerase extracted from the micro-organism E. coli, that was thermolabile and got destroyed at 94°C.
Hence another revolution took place when a few years later a thermophilic micro-organism, Thermus aquaticus was discovered. The latter was capable of living even in boiling water springs. The thermoresistant polymerase of these bacteria, called Taq polymerase, remained active even at 94° C: therefore it could be added just once, at the beginning of the reaction.
Nowadays, in all laboratories in which PCR analyses are carried out on DNA samples, thermostable DNA polymerase enzymes are used.
Nowadays the DNA polymerase, isolated from the thermophile bacterium Thermus aquaticus,  discovered in the thermal springs of Yellowstone Park, is produced with a technique of recombining DNA  in E. coli. In practise, bacteria of E. coli are used as producers of the enzyme Taq polymerase thanks to genetic manipulation that induces E. coli to produce an enzyme identical to the one that Thermus aquaticus produces in the extreme conditions in which it lives.

 
Download "The discovery of DNA" pdf file
Download the junior version pdf file
 

Special reports

From the Multimedia section

Facts

  • 19 April 2022

    Fish are champions migrators

    Migratory fish are true athletes: some of them swim thousands of kilometres during their migration from their birthplace to the…

    31 August 2021

    The thousand uses of lichens

    Throughout history, humans have used lichens for a variety of purposes. The oldest evidence of lichen use dates back to…

  • Unusual vegetables

    Distributed at all latitudes, lichens are able to conquer extreme biotopes, adapting to living in places where plants would find…

    3 October 2017

    Watch out for aliens!

    Italy has some new inhabitants, but that is no cause for celebration: the list of alien species is long. Two…

  • 12 April 2016

    Plants and bacteria giving new “light” to off grid communities

    "Planta lampara", a lamp powered by the energy produced thanks to the combination of plants and bacteria...

    3 April 2012

    The African elephant

    The African elephant is the largest land animal...

  • 19 April 2022

    Fish are champions migrators

    Migratory fish are true athletes: some of them swim thousands of kilometres during their migration from their birthplace to the…

  • 31 August 2021

    The thousand uses of lichens

    Throughout history, humans have used lichens for a variety of purposes. The oldest evidence of lichen use dates back to…

  • Unusual vegetables

    Distributed at all latitudes, lichens are able to conquer extreme biotopes, adapting to living in places where plants would find…