Bioconversion of acrylonitrile to acrylamide using a thermostable nitrile hydratase.

Although providing an attractive route for production of acrylamide from acrylonitrile, utilization of nitrile hydratase enzymes has been limited by the requirement for low temperature bioconversion conditions. This report summarizes a search for thermostable nitrile hydratases from aerobic moderate thermophiles screened for ability to grow on acrylonitrile at concentrations to 1% at elevated temperatures. A new isolate Bacillus sp. BR449 constitutively expresses a thermostable nitrile hydratase with properties including low substrate inhibition and broad temperature range with optimal activity at 55 degrees C. With prolonged exposure, BR449 nitrile hydratase exhibited temperature- dependent inactivation by acrylonitrile, which is attributed to alkylation of nucleophilic sites on the enzyme.