Chitosan beads were prepared by emulsion method and used for the immobilization of omega-transaminase of Vibrio fluvialis. The yield of enzyme immobilization (54.3%) and its residual activity (17.8%) were higher than those obtained with other commercial beads. omega-Transaminase was effectively immobilized on the chitosan beads at pH 6.0. The optimal pH of the immobilized enzyme was pH 9.0, which is the same as that of the free enzyme. The immobilized enzyme on chitosan beads retained ca. 77% of its conversion after five consecutive reactions with the 25 mM substrate, while the immobilized enzyme on Eupergit (R) C retained 12%. Also, the immobilized omega-transaminase on chitosan bead retained 70% of initial activity when it's stored at 4 degrees C for 3.5 weeks. Addition of the co-factor, pyridoxal 5-phosphate (PLP), was needed to maintain the stability of the immobilized omega-transaminase. (C) 2007 Elsevier Ltd. All rights reserved.