The ability of Nocardia sp. 108 to hydrate indole-3-acetonitrile to indole-3-acetamide was identified. Cell culture showed that Nocardia sp. 108 acrylonitrile-hydrating activity reached its maximum, 1209.8 U/g DCW, after cultivated at 28 degrees C for 45 h. Under the biotransformation conditions of 28 degrees C and pH 7.5, the maximal indole-3-acetonitrile conversion ratio and indole-3-acetamide yield were 34.34 and 32.68% (w/w), respectively. Moreover, the K-m and V-max values for the indole-3-acetonitrile biotransformation catalyzed by Nocardia sp. 108 were 1.18 x 10(-2) mol/l and 1.16 x 10(-3) mol/l min. Ethanol supplemented to the reaction system dramatically enhanced indole-3-acetonitrile aqueous solubility. Furthermore, 4% (v/v) ethyl acetate raised the indole-3-acetonitrile bioconversion capacity 78%. (c) 2006 Elsevier Ltd. All rights reserved.