Production of L ‐methionine by immobilized pellets of Aspergillus oryzae in a packed bed reactor

Production of L ‐methionine by immobilized pellets of Aspergillus oryzae in a packed bed reactor was investigated. Based on the determination of relative enzymatic activity in the immobilized pellets, the optimum pH and temperature for the resolution reaction were 8.0 and 60 °C, respectively. The effects of substrate concentration on the resolution reaction were also investigated and the kinetic constants (K m and V m ) of immobilized pellets were found to be 7.99 mmol dm −3 and 1.38 mmol dm −3 h −1 , respectively. The maximum substrate concentration for the resolution reaction without inhibition was 0.2 mol dm −3 . The L ‐methionine conversion rate reached 94% and 78% when substrate concentrations were 0.2 and 0.4 mol dm −3 , respectively, at a flow rate of 7.5 cm 3  h −1 using the small‐scale packed bed reactor developed. The half‐life of the L ‐aminoacylase in immobilized pellets was 70 days in continuous operation. All the results obtained in this paper exhibit a practical potential of using immobilized pellets of Aspergillus oryzae in the production of L ‐methionine. © 2002 Society of Chemical Industry