Metabolic engineering of Escherichia coli to efficiently produce 3-deacyl-2-acyloxyacyl-4′-monophosphoryl-lipid A

3-O-Deacyl-2-O-palmitoyl-4′-monophosphoryl lipid A (MPL) has recently been used in vaccine adjuvant. In this study, an E. coli mutant WZM012 which can effectively produce MPL has been constructed from E. coli MG1655 by genome editing. First, the genes mlaE, pldA, and hns related to the phospholipid transport system in membrane were deleted in MG1655 to accumulate more phospholipid substrate for PagP. In addition, the gene FnlpxE from Francisella novicida which can remove the phosphate group at 1-position of lipid A and the gene SepagL from Salmonella which can remove the acyl chain at 3-position of lipid A were inserted into the chromosome to replace the gene clusters ybgC-cpoB and letAB, respectively, resulting in the strain WZM012. After 24 h fed-batch fermentation of WZM012, lipid A species were isolated and analyzed using thin-layer chromatography and liquid chromatography–mass spectrometry, and 32.76 mg/L MPL was obtained. This engineered E. coli strain could be developed for industrial MPL production.