Colloidal Particle Recovery Using Extended and Shrunken Dextran Generated from Immobilized Enzyme in Porous Membrane

Abstract

A colloidal particle rejection and recovery system using extended and shrunken dextran was proposed. Dextransucrase forms a complex with dextran in an enzymatic reaction with sucrose; therefore dextran is easily formed on membrane pores. A dextransucrase solution was permeated through a Shirasu porous glass membrane at various permeation rates. A sucrose solution was permeated to generate dextran from the active sites of DSase immobilized on the membrane pores, at an immobilized density of 1.9-23 U/g, by controlling the dextran density; the immobilized density of DSase was high when immobilization was performed at a low permeation rate, resulting in a high generated-dextran density of 9.6-28 mg/g. A colloidal particle solution was permeated through the membrane for rejection and recovery. The high-density dextran rejected colloidal particles efficiently. In 50% methanol solution, the rejected colloidal particles leaked through the shrunken dextran structure to achieve smart recovery of colloidal particles.