Figure 4From: Genome replication engineering assisted continuous evolution (GREACE) to improve microbial tolerance for biofuels productionApplication of GREACE to improve n-butanol tolerance and acetate tolerance of E. coli . E. coli cells carrying pQ-lib (white bars), pUC18 (light-grey bars), and pQ-dnaQ (black bars) were cultivated in gradually increased n-butanol or acetate concentrations for acquiring improved tolerance. On each n-butanol or acetate concentration, 3 transfers were repeated before inoculated to the next concentration. n-Butanol or acetate tolerance of the finally isolated E. coli mutant strains (BT12 and AR5) were compared with the wildtype control. (A) Evolution process of E. coli for n-butanol tolerance. (B) Growth assay of E. coli BT12 and E. coli DH5α under serial n-butanol concentrations. (C) Evolution process of E. coli for acetate tolerance. (D) Growth assay of E. coli AR5 and E. coli DH5α under serial acetate concentrations. On each n-butanol or acetate concentration, 3 transfers were repeated before inoculated to the next concentration. As for (A) and (C) the bars represented for the final optical densities (OD600) of each transfer and cultivation.Back to article page