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Open Access Research article

Chromosomal evolution of Escherichia coli for the efficient production of lycopene

Yun-Yan Chen1, Hong-Jie Shen1, Yan-Yan Cui1, Shang-Guang Chen1, Zhi-Ming Weng1, Ming Zhao2* and Jian-Zhong Liu1*

Author Affiliations

1 Biotechnology Research Center and MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Life Science, Sun Yat-Sen University, Guangzhou, 510275, P. R. China

2 Medical Imaging Center, Cancer Center and State Key Laboratory of Oncology in South China, Sun Yat-Sen University, Guangzhou, 510060, P. R. China

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BMC Biotechnology 2013, 13:6  doi:10.1186/1472-6750-13-6

Published: 28 January 2013

Abstract

Background

Plasmid-based overexpression of genes has been the principal strategy for metabolic engineering. However, for biotechnological applications, plasmid-based expression systems are not suitable because of genetic instability, and the requirement for constant selective pressure to ensure plasmid maintenance.

Results

To overcome these drawbacks, we constructed an Escherichia coli lycopene production strain that does not carry a plasmid or an antibiotic marker. This was achieved using triclosan-induced chromosomal evolution, a high gene copy expression system. The engineered strain demonstrated high genetic stability in the absence of the selective agent during fermentation. The replacement of native appY promoter with a T5 promoter, and the deletion of the iclR gene in E. coli CBW 12241 further improved lycopene production. The resulting strain, E. coli CBW 12241(ΔiclR, PT5-appY), produced lycopene at 33.43 mg per gram of dry cell weight.

Conclusions

A lycopene hyper-producer E. coli strain that does not carry a plasmid or antibiotic marker was constructed using triclosan-induced chromosomal evolution. The methods detailed in this study can be used to engineer E. coli to produce other metabolites.

Keywords:
Lycopene; Escherichia coli; Chemically induced chromosomal evolution; Metabolic engineering