| 초록 |
Formate is sustainable feedstock which can be synthesized from CO2. Methylobacterium extorquens is methylotrophic model bacteria, which is able to utilize formate as a sole carbon source. It is also native producer of PHB (poly-3-hydroxybutyrate). In this study, we activated formate utilization in M. extorquens and improved the PHB production. First, to activate the formate transportation by FocA transporter, we optimized medium pH. Second, ftfL was overexpressed under the mxaF promoter, to increase formate assimilation fluxes. Third, activity of fdh2, which is molybdenum-dependent enzyme, was regulated by controlling the molybdenum concentration. As a result, we obtained that pH 6.6 was optimal pH for growth on formate, and ftfL overexpression was very helpful for improvement of cell mass and PHB production. Furthermore, to increase PHB production, phaCAB was overexpressed. Finally, we achieved PHB titer 1.57 g/L, 2.73-fold increase compared to wild type, and PHB content was 46 %. |
