An improved nitrilase-mediated bioprocess for synthesis of nicotinic acid from 3-cyanopyridine with hyperinduced Nocardia globerula NHB-2.

Nitrilase of Nocardia globerula NHB-2 was induced by short-chain aliphatic nitriles (valeronitrile > isobutyronitrile > butyronitrile > propionitrile) and exhibited activity towards aromatic nitriles (benzonitrile > 3-cyanopyridine > 4-cyanopyridine > m-tolunitrile > p-tolunitrile). Hyperinduction of nitrilase (6.67 U mg (DCW) (-1), 18.7 U mL(-1)) was achieved in short incubation time (30 h, 30°C) through multiple feeding of isobutyronitrile in the growth medium. The nitrilase of this organism exhibits both substrate and product inhibition effects. In a fed batch reaction at 1 L scale using hyperinduced resting cells corresponding to 10 U mL(-1) nitrilase activity (1.5 mg(DCW) mL(-1)), a total of 123.11 g nicotinic acid was produced at a rate of 24 g h(-1) g (DCW) (-1).