Chromosomal evolution of Escherichia coli for the efficient production of lycopene.
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.
Biotechnology Research Center and MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Life Science, Sun Yat-Sen University, Guangzhou, 510275, PR China.
Yun-Yan
YY
Chen
Hong-Jie
HJ
Shen
Yan-Yan
YY
Cui
Shang-Guang
SG
Chen
Zhi-Ming
ZM
Weng
Ming
M
Zhao
Jian-Zhong
JZ
Liu
D018533:Biomass; D002338:Carotenoids / Q000096:biosynthesis*; D002875:Chromosomes / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics; D019143:Evolution, Molecular; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D055786:Gene Knockout Techniques; D000077276:Lycopene; D010957:Plasmids / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D015534:Trans-Activators / Q000235:genetics; D014260:Triclosan / Q000494:pharmacology
C089118:AppY protein, E coli; D029968:Escherichia coli Proteins; D015534:Trans-Activators; D002338:Carotenoids; D014260:Triclosan; D000077276:Lycopene