Engineering analysis of continuous production of L-aspartic acid by immobilized Escherichia coli cells in fixed beds.

The reaction mechanism and decay behavior of aspartase activity for immobilized Escherichia coli cells were investigated by using a sectional packed column. Reaction within the immobilized cell column proceeded at zero-order on substrate solutions ranging in concentration from 0.1 to 1.0M, and the initial reaction rate was found to be 1.556 X 10(-2) mol/min/liter of immobilized cells. The effect of temperature on the reaction rate constant was investigated. The Arrhenius plot was a straight line at temperatures below 43 degrees C, and the activation energy for immobilized cells was calculated to be 12.36 kcal/mol. Aspartase activity in the immobilized cell column decayed exponentially and uniformly in all sections of a column. Its half-life was approximately 120 days. The rate of formation of L-aspartic acid was shown to be independent of column dimensions.