| 초록 |
Plasmids require addition of antibiotics for their stable maintenance despite the growing concerns over economic and environmental problems. Here, we reinvented the auxotrophic plasmid maintenance system for stable and tunable gene expression during antibiotic-free cultivation. We expressed one of essential genes, infA encoding translation initiation factor (IF-1), based on plasmid rather than chromosome. With this, the gene expression was stably maintained for 5 days with minimized cell-to-cell variation. Moreover, plasmid copy number (PCN) was rationally tunable in 5-fold by varying expression of infA. To demonstrate its usability, the strategy was applied in metabolic engineering for chemical production. Notably, PCN control enabled significantly improved production of both itaconic acid (160%) and lycopene (278%) compared to cultivation with antibiotics. Collectively, the developed strategy could be a platform for production of value-added products in antibiotic-free cultivation. |
