CHARACTERIZATION OF GLUTAMINASE IMMOBILIZ ED ON MAGNETIC SUPPORT (MC 4 P) IN SOY-SAUCE MODEL SOLUTION .2. A STUDY OF CONVERSION OF GLUTAMINE TO GLUTAMIC-ACID BY AN IMMOBILIZED GLUTAMINASE ON A SUPPORT HAVING MAGNETIC SENSITIVITY

Glutaminase from Bacillus subtilis sp. was immobilized on a magnetic s upport (MC4P) composed of partially deacetylated chitin (PDAC), chitos an and Fe3O4. The immobilized glutaminase in concentrated salt solutio n was more stable than glutaminase in the free form at acidic pHs and at a high temperature (60-degrees-C). The same tendency was observed e ven in ethanol saline solution (ethanol concn. 20%, NaCl concn. 16%). When the reaction mixture of 1.5% glutamine solution containing 16% Na Cl was supplied to a column reactor at a space velocity of 0.68 h-1, t he period of fifty percent decline of initial conversion rate of the i mmobilized glutaminase required 169 days at 40-degrees-C, 114 days at 50-degrees-C, and 100 days at 60-degrees-C, but the conversion rate at 30-degrees-C did not change after 180 days. Glutamic acid (4.4-5.5 mg /ml) was produced from glutamine in immature soy sauce moromi filtrate through the bioreactor at a space velocity of 1.0 h-1. This bioreacto r system worked well over a 35 day period. The immobilized glutamine w as supplied repeatedly to different koji hydrolysates and recovered ea ch time by exposure to a magnetic field. By this method glutamic acid (3.4-3.6 mg/ml) was produced during a 72 h period involving four recyc lings of the enzyme.