Constitutive acetonitrile hydrolysing activity of Nocardia globerula NHB-2: Optimization of production and reaction conditions.

Nocardia globerula NHB-2 exhibited an intracellular acetonitrile hydrolysing activity (AHA) when cultivated in nutrient broth supplemented with glucose (10.0 g/l) and yeast extract (1.0 g/l), at pH 8.0, 30 degrees C for 21 hr. Maximum AHA was recorded in the culture containing 0.1 M of sodium phosphate buffer, (pH 8.8) at 45 degrees C for 15 min with 600 micromol of acetonitrile and resting cells of N. globerula NHB-2 equivalent to 1.0 ml culture broth. This activity was stable up to 40 degrees C and was completely inactivated at or above 60 degrees C. About five-fold increase in AHA was observed after optimization of culture and reaction conditions. Under the optimized conditions, this organism hydrolyzed various nitriles and amides such as propionitrile, benzonitrile. acetamide, and acrylamide to corresponding acids. This nitrile/amide hydrolysing activity of N. globerula NHB-2 has potential applications in enzymatic synthesis of organic acids and bioremediation of nitriles and amides contaminated soil and water system.