On the Road towards Chemically Modified Organisms Endowed with a Genetic Firewall


  • We are indebted to Dr. Michael G. Hoesl and Dr. Lars Merkel for critical reading of this manuscript and numerous productive discussions on this subject.


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An automated system for the continuous cultivation of cells in suspension has been used to globally change the composition of the DNA genome of E. coli. Thymine was replaced almost completely by 5-chlorouracil through artificial evolution of cells, during which the bacterial genome accumulated hundreds of mutations under permanent conditions of proliferation and selection. The resulting 5-chlorouracil-adapted descendants had the ability to grow on 5-chlorouracil.