Corynebacterium glutamicum is an industrial strain used for the production of valuable chemicals such as L-lysine and L-glutamate. Although C. glutamicum has various industrial applications, a limited number of tunable systems are available to engineer it for efficient production of platform chemicals. Therefore, in this study, we developed a novel tunable promoter system based on repeats of the Vitreoscilla hemoglobin promoter (Pvgb). Tunable expression of green fluorescent protein (GFP) was investigated under one, four, and eight repeats of Pvgb (Pvgb, Pvgb4, and Pvgb8). The intensity of fluorescence in recombinant C. glutamicum strains increased as the number of Pvgb increased from single to eight (Pvgb8) repeats. Furthermore, we demonstrated the application of the new Pvgb promoter-based vector system as a platform for metabolic engineering of C. glutamicum by investigating 5-aminovaleric acid (5-AVA) and gamma-aminobutyric acid (GABA) production in several C. glutamicum strains. The profile of 5-AVA and GABA production by the recombinant strains were evaluated to investigate the tunable expression of key enzymes such as DavBA and GadBmut. We observed that 5-AVA and GABA production by the recombinant strains increased as the number of Pvgb used for the expression of key proteins increased. The recombinant C. glutamicum strain expressing DavBA could produce higher amounts of 5-AVA under the control of Pvgb8 (3.69 ± 0.07 g/L) than the one under the control of Pvgb (3.43 ± 0.10 g/L). The average gamma-aminobutyric acid production also increased in all the tested strains as the number of Pvgb used for GadBmut expression increased from single (4.81–5.31 g/L) to eight repeats (4.94–5.58 g/L).
Bibliographical noteFunding Information:
This work was supported by the Technology Development Program to Solve Climate Changes on Systems Metabolic Engineering for Biorefineries from the Ministry of Science and ICT (MSIT) through the National Research Foundation (NRF) of Korea (NRF-2015M1A2A2035810), the Bio & Medical Technology Development Program MSIT through the NRF of Korea (NRF-2018M3A9H3020459) and the Lignin Biorefinery from MSIT through the NRF of Korea (NRF-2017M1A2A2087634).
© 2018 by the authors.
- Corynebacterium glutamicum
- Expression vectors
- Synthetic biology
- Tunable expression system