Monday, July 25, 2011
Grand Ballroom, 5th fl (Sheraton New Orleans)
Inhibitor tolerance in biocatalysts is a complex phenotype. The rational design of more robust microbial systems generally requires knowledge of the genetic determinants involved in the desired trait. Towards this goal, we have developed a novel experimental adaptive evolution method, Visualizing Evolution in Real-Time (VERT), for the evolutionary engineering of microbial systems for complex phenotypes. VERT allows the identification of adaptive events and helps to facilitate the isolation of adaptive mutants from the evolving population for further analysis and characterization. We applied VERT to evolve Escherichia coli for enhanced tolerance to the biofuel, butanol. Butanol is highly toxic to microorganisms, with most strains being able to tolerate up to 2% (v/v) of this organic solvent. Wild-type E. coli can tolerate up to approximately 1% (v/v) of n-butanol. We successfully evolved E. coli for enhanced butanol tolerance using VERT. The butanol tolerant mutants were isolated from the population and analyzed to elucidate the molecular mechanisms involved in tolerance.