The objectives of this proposal are to study a new method to prepare immobilized biocatalysts by absorbing acrylamide and an enzyme solution into diatomaceous silica followed by a polymerization reaction. The immobilized enzyme or microorganisms prepared by this technique will have large mechanical strength compared to unmodified polyacrylamide gel. Beta-galactosidase is chosen for this study because of its application in reducing lactose content in milk. Factorial studies on the polymerization will be made on the following two variables: (1) the ratio of acrylamide and bifunctional N,N'-methylenebisacrylamide, and (2) the percentage of organic compound in solution. These studies will locate the best condition to make a gel-silica composite carrier. The immobilized enzyme will be packed into column to study the hydrolization kinetics and mass transfer parameters. Parameters in the Michaelis-Menten equation will be determined in a stirred reactor. Mass transfer parameters will be determined from moment analysis of pulse inputs and input-output ratios using substrates with very low concentrations so that the model for a first order reaction can be applied. The parameters obtained will be correlated with pH, flow rate and temperature. Stability studies will also be made to investigate the effects of denaturation agents, temperature, and storage period on the activity of the enzyme. The results of this study will enable one to hydrolyze lactose in milk on a large scale. The same method of immobilization can be applied to other enzymes, or live microorganisms.
