Continuous Production of l ‐Alanine Using Pseudomonas dacunhae Immobilized with Carrageenan

Summary Continuous production of l‐alanine from l‐aspartic acid using immobilized Pseudomonas dacunhae was investigated. Pseudomonas dacunhae cells were immobilized with carrageenan gel. The l‐aspartate β‐decarboxylase activity of immobilized cells was enhanced by incubating the immobilized cells with a solution of 1M ammonium l‐aspartate (pH 5.5) containing 0.1mM pyridoxal‐5′‐phosphate (PLP) at 37°C over 20 hr. The enzyme activity of immobilized cells was 59% that of intact cells. The pH profile of the enzyme reaction was broader in the immobilized cells than in the free cells. The enzyme activity of immobilized cells was maintained through repeated uses when a substrate solution containing 0.1mM PLP was used. Complete conversion of l‐aspartate to l‐alanine was attained when a solution of 2M ammonium l‐aspartate (pH 6.2) containing 0.1mM PLP was passed upward through the immobilized cell column at a retention time of 8 hr at 37°C. Glutaraldehyde treatment of the immobilized cells resulted in a slight decrease of the enzyme activity but a marked increase of the operational stability. The half‐life of enzyme activity was 46 days in glutaraldehyde‐treated immobilized cells.