Efficient biotransformation of l-lysine into cadaverine by strengthening pyridoxal 5’-phosphate-dependent proteins in Escherichia coli with cold shock treatment

Abstract

Cadaverine is a five-carbon diamine which serves as an important biochemical for the synthesis of bio-based nylon. It can be produced by the bioconversion of l-lysine with lysine decarboxylase (CadA; EC 4.1.1.18) and relies on cofactor pyridoxal 5′-phosphate (PLP), thus to recycle PLP from the super-salvage pathway by the genes of pdxH, pdxY, and pdxK in Escherichia coli is crucial and urgent. In this study, the optimal PLP production per gram dry cell weight (i.e., 7008 nmol/g-DCW) increased 30-fold in E. coli BL21 by overexpressing pdxY. Cadaverine production reached 34.7 g/L or 41.2 g/L by in vivo CadA co-expression with plasmids of pJY or pPK. The better conversion was obtained in APK strain (co-expressing CadA and pPK) via whole cell biotransformation, resulting in 97 % and 68 % conversion of 0.4 M and 1.2 M L-lysine to 39.6 g/L and 83.2 g/L cadaverine, respectively. Finally, cold shock treatment of whole-cell biocatalyst showed a significant increasing and achieved the highest cadaverine productivity of 121 g/L/h compared to the previous reports.