Efficient L-phosphinothricin production by engineered Escherichia coli co-expressing glutamate dehydrogenase, glucose dehydrogenase and NAD kinase with NADPH regeneration

L-Phosphinothricin (L-PPT) is the active compound of a broad-spectrum herbicide. In this study, we biosynthesized L-PPT via the asymmetric reduction of 2-carboxy-4-(hydroxymethylphosphoryl) butyric acid (PPO) using a whole-cell biocatalyst. Glutamate dehydrogenase from Pseudomonas moorei ( Pm GluDH), Glucose dehydrogenase from Exiguobacterium sibiricum ( Es GDH) and NAD kinase from Corynebacterium glutamicum ( Cg NADK) were coexpressed in E. coli , significantly increasing the catalytic efficiency by regenerating more NADPH to promote PPO reduction. Following the optimization of balancing the co-expression of the three enzymes in pETDuet-1 and pCDFDuet-1, the coexpressing strain increases in the intracellular NADP(H) concentration to 54.9 μmol/g DCW, which was 3.8-fold higher than the control. The co-expression system exhibited optimal activity at a temperature of 35°C, pH 7.5, and the glucose to PPO molar ratio of 1.4:1. In a 30 L bioconversion system the final concentration and productivity of L-PPT reached 79.8 g/L (>99% ee ) and 1440 g/(L·d), respectively. These results will contribute to the industrial biological production of L-PPT.