title: Engineering analysis of continuous production of L-aspartic acid by immobilized Escherichia coli cells in fixed beds.
abstract: 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.
mesh_terms: D001220:Aspartate Ammonia-Lyase / Q000378:metabolism; D001224:Aspartic Acid / Q000096:biosynthesis*; D001431:Bacteriological Techniques; D002616:Chemical Engineering; D004926:Escherichia coli / Q000201:enzymology / Q000378:metabolism*; D005650:Fumarates / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D012212:Rheology; D013696:Temperature
chemical_list: D005650:Fumarates; D000644:Quaternary Ammonium Compounds; D001224:Aspartic Acid; D001220:Aspartate Ammonia-Lyase