Bioconversion of acrylonitrile to acrylamide using a thermostable nitrile hydratase

Although providing an attractive route for production of acrylamide from ac rylonitrile, utilization of nitrile hydratase enzymes has been limited by t he requirement for low temperature bioconversion conditions. This report su mmarizes a search for thermostable nitrile hydratases from aerobic moderate thermophiles screened for ability to grow on acrylonitrile at concentratio ns to 1% at elevated temperatures. A new isolate Bacillus sp. BR449 constit utively expresses a thermostable nitrile hydratase with properties includin g low substrate inhibition and broad temperature range with optimal activit y at 55 degrees C. With prolonged exposure, BR449 nitrile hydratase exhibit ed temperature-dependent inactivation by acrylonitrile, which is attributed to alkylation of nucleophilic sites on the enzyme.