Engineering of Escherichia coli for Lycopene Production Through Promoter Engineering

The control of gene expression is critical for metabolic engineering. The multi-copy plasmids has been widely used for high-level expression of genes. However, plasmid-based expression systems are liable to genetic instability and require a selective pressure to assure plasmid stability. In this study, we first constructed a lycopene producer Escherichia coli through promoter engineering. Saccharomyces cerevisiae mevalonate (MEV) pathway was also optimized to balance expression of the top and bottom MEV pathway by using the different strength promoters. The chromosomal heterologous expression of the optimized S. cerevisiae MEV pathway can further improved lycopene production. The final engineered strain, E. coli LYCOP 20, produced lycopene of 529.45 mg/L and 20.25 mg per gram of dry cell weight in the fed-batch culture. The engineered strain does not have a plasmid or antibiotic marker. This strategy used in this study can be applied in pathway engineering of E. coli and other bacteria.