Identification of novel knockout and up-regulated targets for improving isoprenoid production in E. coli

Discovery of novel potential genetic tar- gets to increase the supply of isoprenoid precursors, isopentyl/dimethylallyl diphosphate, is of importance for microbial production of isoprenoids. Here, to improve isoprenoid precursor supply, a flux distribu- tion comparison analysis, based on the genome-scale model, was utilized to simultaneously predict the knockout, down- and up-regulated targets in Esche- richia coli. 51 targets were in silico discovered. All knockout and up-regulated targets were experimen- tally tested to enhance lycopene production. Five knockout targets (deoB, yhfw, yahI, pta and eutD) and four up-regulated targets (ompN, ompE, ndk and cmk) led to 10-45 % increases of lycopene yield, respec- tively, which had not been uncovered in previous studies. When engineering of the five most significant targets gdhA, eutD, tpiA, ompE and ompN, were combined the lycopene titer improved by 174 % in shake-flask and 81 % in bioreactor fermentations with a maximum yield of 454 mg l -1 .