title: Immobilization of Escherichia coli Cells Containing Aspartase Activity with Polyurethane and Its Application for l-Aspartic Acid Production.
abstract: Whole cells of Escherichia coli containing aspartase activity were immobilized by mixing a cell suspension with a liquid isocyanate-capped polyurethane prepolymer (Hypol). The immobilized cell preparation was used to convert ammonium fumarate to l-aspartic acid. Properties of the immobilized E. coli cells containing aspartase were investigated with a batch reactor. A 1.67-fold increase in the l-aspartic acid production rate was observed at 37 degrees C as compared to 25 degrees C operating temperature. The pH optimum was broad, ranging from 8.5 to 9.2. Increasing the concentration of ammonium fumarate to 1.5 M from 1.0 M negatively affected the reaction rate. l-Aspartic acid was produced at an average rate of 2.18 x 10 mol/min per g (wet weight) of immobilized E. coli cells with a 37 degrees C substrate solution consisting of 1.0 M ammonium fumarate with 1 mM Mg (pH 9.0).
authors.affiliation: Research Division, W. R. Grace & Co., Columbia, Maryland 21044.
authors.forename: M C
authors.initials: MC
authors.lastname: Fusee
authors.forename: W E
authors.initials: WE
authors.lastname: Swann
authors.forename: G J
authors.initials: GJ
authors.lastname: Calton