High-level l-lysine bioconversion into cadaverine with enhanced productivity using engineered Escherichia coli whole-cell biocatalyst

Abstract

Cadaverine (also known as 1,5-diaminopentane) is one of the most potential bio-based products with a wide range of industrial applications. Bio-based polyamides configured with cadaverine demonstrated excellent physical properties comparable to conventional petrochemical-based polyamides (polyamides 6 and 66). In this study, recombinant Escherichia coli overexpressing CadA was applied as whole-cell biocatalyst for efficient l-lysine bioconversion into cadaverine. Optimization of the reaction conditions and kinetic study for whole-cell biotransformation was performed by investigating the influence of initial pH (4–8), buffer concentration (0−500 mM), biocatalyst concentration (0.33–1.98 g DCW/L), l-lysine concentrations (1−2 M), and pyridoxal-5’-phosphate concentration (0 to 0.05 mM). Robustness of the constructed biocatalyst was demonstrated with high enzymatic activity over a wide range of pH, stability at acidic pH, and excellent tolerance to high l-lysine concentration. Bioconversion medium without pH adjustment and buffer addition was chosen due to the added benefits of cost efficiency and operation simplification. From the perspective of “green” economy, the whole-cell biocatalyst showed an outstanding efficiency in the bioconversion of l-lysine to cadaverine at high substrate concentration and successfully achieved a cadaverine titer, molar yield and productivity of 1.419 M, 94.6 % and 709.5 mM/h, respectively and the productivity is higher compared to other previous reports. The biocatalyst can be recycled and reused at least three times with over 71.8 % of its original bioconversion efficiency.