ABSTRACT
Studies on lycopene synthesis in Escherichia coli were not only able to gain the strains with high yield and less by-products, but also able to test functions of genes or gene clusters. In this article, the cDNA sequences of tomato LeGGPS2 and LePSY1 as well as the coding sequence of crtI from Erwinia uredovora, each of which was added a ribosome biding site, were controlled by T7 promoter and terminator alone or combined, and expressed in E. coli BL21 (DE3) to induce lycopene synthesis. The results show that only T7::crtI-LeGGPS2-LePSY1 expressed tri-cistronically could produce lycopene, and 2.124 mg/g dry cell weight oflycopene was obtained when fermented for 5 h at 30 degrees C after mixing 80 micromol/L IPTG at the later logarithmic phase while the seed broth of 1:50 (V/V) was inoculated into LB medium (pH 6.8) containing 3% sucrose and cultured for 8 h at 37 degrees C. The results confirmed the function of the prokaryonized LeGGPS2 and LePSY1 and their synergy with crtI, and also laid a foundation to establish an independent lycopene synthetic pathway in the tomato plastid.