초록 |
Formate is environmentally sustainable C1 feedstock which is synthesized from electrochemical reduction of CO2. M. extorquens, a methylotroph, is able to utilize formate as a sole carbon source and produce PHB natively. In this study, we improved the formate utilization and the PHB production by optimizing the medium conditions and engineering the strain genetically. First, to activate the formate transportation by FocA transporter, we optimized medium pH. Second, ftfL (formate-tetrahydrofolate ligase) was overexpressed to increase formate assimilation fluxes. Third, activity of Fdh2 which is Mo-dependent enzyme was regulated by controlling the concentration of Mo. As a result, we obtained that keeping pH 6.6 and ftfL overexpression were very helpful for improvement of growth and PHB production. Finally, phaCAB, PHB synthesis pathway, was overexpressed and we achieved PHB titer 1.57 g/L, 273% increase compared to wild type. This proved successful conversion of formate into biopolymer. |