Establishment of Bioprocess for Synthesis of Nicotinamide by Recombinant Escherichia coli Expressing High-Molecular-Mass Nitrile Hydratase.

Application of engineered bacteria expressing nitrile hydratase for the production of amide is getting tremendous attention due to the rapid development of recombinant DNA technique. This study evaluated the effect of 3-cyanopyridine concentrations on nicotinamide production using recombinant Escherichia coli strain (BAG) expressing high-molecular-mass nitrile hydratase from Rhodococcus rhodochrous J1, and established proper process of whole-cell catalysis of 3-cyanopyridine and high cell-density cultivation. The process of substrate fed-batch was applied in the production of nicotinamide, and the concentration of product reached 390 g/L under the condition of low cell-density. After the high cell-density cultivation of BAG in 5 L bioreactor, the OD600 of cell attained 200 and the total activity reached 2813 U/mL. Different high density of BAG after fermentation in the tank was used to catalyze 3-cyanopyridine, and the concentration of nicotinamide reached to 508 g/L in just 60 min. The productivity of BAG was 212% higher than that of R. rhodochrous J1, and it is possible that BAG is able to achieve industrial production of nicotinamide.