Focusing on the task-specific properties of ionic liquids (ILs), a novel IL was designed by combining the quaternary ammonium cationic surfactant, [N1,1,1,1](+), with benign amino acid anion ([Cys]), and was successfully employed in whole-cell-catalyzed bioreduction by Trichoderma asperellum ZJPH0810 using an ionic liquid-distilled water medium. As expected, based on better understanding about the effects of ILs' characteristics of cations and anions on T. asperellum ZJPH0810-catalyzed bioreduction and the optimization of reaction parameters, the developed tetramethylammonium cysteine ([N1,1,1,1][Cys])containing system is more efficient for the asymmetric reduction of 3,5-bis(trifluoromethyl) acetophenone to (R)-[3,5-bis(trifluoromethyl) phenyl] ethanol by whole-cell catalysis in contrast to that in monophasic aqueous system. Herein, a new biotechnological application for designed type of ILs is proposed due to its novel property of strengthening coenzyme regeneration during the bioreduction process. The designed IL [N1,1,1,1][Cys] was also evaluated in Candida tropicalis 104-catalyzed bioreduction to board its application, with remarkable success. (C) 2014 Elsevier Ltd. All rights reserved.