Articles

Journal of Molecular Evolution

, Volume 41, Issue 2, pp 113-114

Extremo-phage: In vitro selection of tolerance to a hostile environment

  • Kanika GuptaAffiliated withBiotechnology and Biochemical Engineering Program, Thayer School of Engineering, Dartmouth College
  • , Yih LeeAffiliated withBiotechnology and Biochemical Engineering Program, Thayer School of Engineering, Dartmouth College
  • , John YinAffiliated withBiotechnology and Biochemical Engineering Program, Thayer School of Engineering, Dartmouth College

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Abstract

Extremophiles are microorganisms that thrive under extreme conditions such as temperatures above 65°C, pHs below 4 or above 10, salt concentrations above 0.5 m, or pressures of 600 atm. While studies of enzymes either isolated from extremophiles, or generated using site-specific mutagenesis, or adapted by in vivo or in vitro selection have established a precedent for the engineering and application of proteins at extreme conditions, generalization of the approaches to more complex multimolecular or multitask systems has remained elusive. Here we demonstrate that a significantly more complex system—a bacteriophage—can over a number of generations be adapted to tolerate a hostile and unnatural environment. An in vitro selection strategy was used to adapt phage to urea, a protein denaturing agent. As the concentration of urea employed in selections over 20 generations was gradually increased from 5 to 9 m, the surviving phages steadily improved their tolerance, finally achieving a greater than 350-fold stability enhancement over the original population.

Key words

In vitro selection Bacteriophage evolution Protein stability Urea Extremophile