De novo biosynthesis of α‐aminoadipate via multi‐strategy metabolic engineering in Escherichia coli

As a non‐protein amino acid, α‐aminoadipate is used in the fields of medicine, chemical engineering, food science, and others. For example, α‐aminoadipate is an important precursor for the production of β‐lactam antibiotics. Currently, the synthesis of α‐aminoadipate depends on chemical catalysis that has the disadvantages of high cost, low yield, and serious pollution. In this study, we construct a biosynthesis pathway of α‐aminoadipate in Escherichia coli using lysine as a precursor. In addition, we regulate the cell metabolism to improve the titer of α‐aminoadipate via multi‐strategy metabolic engineering. First, a novel synthetic pathway was constructed to realize de novo synthesis of α‐aminoadipate with titers of 82 mg/L. Second, the key enzymes involved in enhancing precursor synthesis were overexpressed and the CO(2) fixation process was introduced, and these led to 80% and 34% increases in the α‐aminoadipate concentration, reaching 147 and 110 mg/L, respectively. Third, cofactor regulation was used to maintain the coupling balance of material and energy, with the intracellular α‐aminoadipate concentration reaching 140 mg/L. Fourth, the weakening of the synthesis of acetic acid was used to strengthen the synthesis of α‐aminoadipate, and this resulted in the enhancement of the α‐aminoadipate concentration by 2.2 times, reaching 263 mg/L. Finally, combination optimization was used to promote the production of α‐aminoadipate. The titers of α‐aminoadipate reached 368 mg/L (strain EcN11#) and 415 mg/L (strain EcN11##), which was 3.5 and 4 times higher than that of the parent strain. With these efforts, 1.54 g/L of α‐aminoadipate was produced under fed‐batch conditions by strain EcN11#. This study is the first to present the effective biosynthesis of α‐aminoadipate in E. coli using multi‐strategy metabolic engineering.