Immobilization of Escherichia coli cells containing aspartase activity with kappa-carrageenan. Enzymic properties and application for L-aspartic acid production.

Whole cells of Escherichia coli having high aspartase (L-asparate ammonialyase, EC 4.3.1.1) activity were immobilized by entrapping into a kappa-carrageenan gel. The obtained immobilized cells were treated with glutaraldehyde or with glutaraldehyde and hexamethylenediamine. The enzymic properties of three immobilized cell preparations were investigated, and compared with those of the soluble aspartate. The optimum pH of the aspartase reaction was 9.0 for the three immobilized cell preparations and 9.5 for the soluble enzyme. The optimum temperature for three immobilized cell preparations was 5--10 degrees C higher than that for the soluble enzyme. The apparent Km values of immobilized cell preparations were about five times higher than that of the soluble enzyme. The heat stability of intact cells was increased by immobilization. The operational stability of the immobilized cell columns was higher at pH 8.5 than at optimum pH of the aspartase reaction. From the column effluents, L-aspartic acid was obtained in a good yield.