Specificity of adaptation with different carbon sources and alcohols. Specificity of adaptation of clones G3.2 (isolated from G3 evolution end population) and X3.5 (isolated from X3 evolution end population) was examined by assessing isobutanol tolerance of each clone and the parent E. coli EcNR1 on glucose minimal medium, xylose minimal medium, and LB medium. Tolerance to ethanol, isopropanol, and n-hexanol was also determined for these strains and the parent E. coli EcNR1. (A) Fitness (relative to parent E. coli EcNR1) of G3.2 and X3.5 on glucose, xylose, and LB medium with 0% (w/v) isobutanol, (B) Fitness (relative to parent E. coli EcNR1) of G3.2 and X3.5 on glucose, xylose, and LB medium with 1% (w/v) isobutanol, (C) Fitness of G3.2 and X3.5 (in glucose vs. xylose) at 0%, 1%, and 1.5% (w/v) isobutanol, (D) Percent relative inhibition of E. coli EcNR1 compared to G3.2 and X3.5 (defined as , where μWT is the maximum specific growth rate of E. coli EcNR1, and μMUT is the maximum specific growth rate of G3.2 or X3.5) on ethanol (3.5% v/v), isopropanol (2.5% v/v), isobutanol (0.5% w/v), and hexanol (0.25% v/v). The alcohol concentrations correspond to approximately 1/2 the minimum growth inhibiting concentration (MIC) for the parent E. coli EcNR1 strain.