Screening Of The Key Gene In Terpenoids Metabolic Pathway In Engineered Escherichia Coli Strains For Lycopene Production

Terpenoids are a family of compounds that use isoprene as structural unit,which are widely applied in many areas.Lycopene is a terpenoid pigment that has diverse applications in the fields of food and medicine.Lycopence is formed from two common precursors:isopentenyl pyrophosphate(IPP)and dimethylallyl pyrophosphate(DMAPP),whch is the same as other terpenoids.IPP and DMAPP was synthesized via MEP pathway or MVA pathway.Isopentenyl diphosphate isomerase(IDI)is one of the most important enzymes in two pathways,and it regulates the ratio of IPP and DMAPP to ensure the metabolic balance.So it is one of the most important targets during metabolic engineering.In this study,we systematic optimized the idi gene using metabolic engineering means in Escherichia coli with the purpose of obtaining the engineering strains which had high yield of lycopene.Here,typel and type2 genes of isopentenyl diphosphate isomerase were cloned from different species,including prokaryotic microbe,eukaryotic microbe,plant,archaea,and they were heterologous expressed in Escherichia coli.At the same time,we compared the lycopene yield in the engineering strains that on the background of MEP and MVA pathways respectively.In a MEP-enhanced background in Escherichia coli,we transformed IDI recombinant vectors from the different sources along with the lycopene synthetic module pLY10-2Rk.On the other hand,the different IDI recombinant vectors and the pLY10-2Rk were transformed into the E.coli with MVA background.We detected the lycopene yield from the two types of strains,and found that the same IDI in two pathways background strains had different performance.For constructed a high yield lycopene production strain,we expressed heterologous IDI coordinate relevant target in the MEP pathway.And ScIDI and BsIDI were the most efficient IDI for lycopene production,and the yield is up to 9.96 mg/g DCW,8.78 mg/g DCW.Limited to the MEP pathway's characteristics,we simultaneously used the efficient PtIDI in MVA background strains,with the help of the assembly method OLMA,to optimise the lycopene synthetic module.The engineered strain produced 57.78mg/g DCW lycopene.The results will provide new information for further metabolic engineering study involved in production of lycopene and other terpenoid.