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Fig. 6 | Biotechnology for Biofuels

Fig. 6

From: Metabolic engineering of Zymomonas mobilis for anaerobic isobutanol production

Fig. 6

Strategy to improve isobutanol production in Z. mobilis by replacing the inducible Ptet promoter driving the kdcA gene with different constitutive strong promoters. Ptet promoter was replaced with three recombinant strains constructed for isobutanol production. ZMQ3, kdcA driven by Pgap was integrated at chromosomal gene ZMO0038 locus; ZMQ4, kdcA driven by Pgap was integrated at the native plasmid pZM36-005 locus; ZMQ5, kdcA driven by Peno was integrated at chromosomal gene ZMO0038 locus (a). Ethanol and isobutanol production of Z. mobilis strains ZMQ3, ZMQ4, and ZMQ5 12-h post-inoculation in RMG5 (b). Growth, as well as ethanol (Eth) and isobutanol (Iso) production in ZMQ3-A2, ZMQ3-A3, and ZMQ3-A4 in RMG5 with the tetracycline induction at different concentrations (c). Growth curve of ZMQ3-A4 in RMG5 under the induction of different tetracycline concentrations of 0, 0.2, and 1 μg/mL (d). 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 or more technical replicates. Error bars represent standard deviations

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