Genome-Wide Evolution for Improved Tolerance and Production

1 Genome-Wide Evolution for Improved Tolerance and Production 

Mutagenesis and screening have been used in a variety of organisms to obtain mutants with improved ethanol production ability. For example, a mutant of P. stipitis was obtained by UV mutagenesis, which exhibited increased ethanol fermentation ability from xylose [114]. This mutant was able to produce 43gl ethanol from 114gl xylose, a 38% increase relative to the original strain. 

As mentioned above, the construction of the widely used ethanologenic E. call KOll included a period of directed evolution for improved tolerance and production [68]. This evolution involved a repeated series of dilution and 

The use of evolution to improve tolerance with the goal of also improving production has also been widely adopted by the metabolic engineering community, though with mixed results. In some cases, increased tolerance is associated with improved production. For example, the metabolic evolution of E. coli for fatty acid tolerance resulted in improved fatty acid production [125]. Evolution of non-transgenic, ethanologenic E. coli KCOl for increased ethanol tolerance resulted in improved production [126], similar to the observed outcome with evolution of KOll for ethanol tolerance to produce strain LYOl. 

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