Fig. 4

Integration of heterologous KdcA gene from L. lactis into the chromosome or a native plasmid of Z. mobilis for stable isobutanol production. ZMQ1 and ZMQ2 were constructed by integrating the kdcA gene driven by tetracycline-inducible promoter Ptet into the ZMO0038 chromosomal locus or the pZM36-005 locus in the native plasmid pZM36, respectively (a). Concentrations of isobutanol (Iso) and ethanol (Eth) for Z. mobilis strains ZMQ1 and ZMQ2 in RMG5 with tetracycline induction at 0, 0.2, and 1 μg/mL (b). Tc 0, Tc 0.2 and Tc 1 represented the tetracycline concentrations of 0, 0.2, and 1.0 μg/mL that was added into the medium one time at the beginning of the experiment, respectively. At least two independent experiments were carried out with similar results. Values are the mean of one representative experiment with three technical replicates. Error bars represent standard deviations