A novel hollow‐fiber reactor with reversible immobilization of lactase

Abstract

Experimental and theoretical studies on a backflush hollow-fiber enzymatic reactor (HFER) were conducted in this work for a lactose/ lactase system. An A. niger lactase was chosen, from the four lactases tested, for reversible immobilization in the sponge layers of the fibers. An enzyme loading procedure was developed that allowed reliable and reproducible operation of the hollow-fiber reactor and produced industrially significant conversions without apparent change in the activity or stability of the lactase used. This reversible immobilization scheme also permitted easy replacement of the enzyme used. The performance of the backflush HFER was investigated and a large number of data concerning its operation were obtained and interpreted. Momentum and mass transports in such a HFER were analyzed, and mathematical models that took the experimental findings into consideration were also developed and solved analytically and/or numerically. Predictions from the computer model developed in this work were found to be in excellent agreement with the experimental data collected, suggesting the possibility of a priori design of a process-scale backflush HFER. With minor modifications, the models developed are expected to be applicable to hollow-fiber reactors with a wide selection of immobilized cells, organelles, and other enzymes. C. K. S. Jones, R. Y. K. Yang, E. T. WhiteDepartment of Chemical Engineering University of Queensland St. Lucia, QLD 4067 Australia Introduction A large number of enzyme immobilization schemes involve chemical coupling of enzymes to a solid support. In addition to chemical binding, physical techniques such as adsorption, gel entrapment, and encapsulation have been used. Enzymes immobilized by encapsulation usually can expect to experience an environment similar to that of free enzymes in an aqueous solution. In particular, if the enzyme is encapsulated after the formation of an encapsulating medium, it should retain its intrinsic kinetic properties.Examples of the last method of immobilization are the hollow-fiber enzymatic reactor (HFER) investigated by Breslau and Kilcullen (1975), Robertson et al. (1976), Rony (1971), and Waterland et al. (1974. All these reactors allow the enzymes to be truly immobilized under mild conditions without causing alteration of their inherent kinetic behaviors. However, Corrspondencc concerning this paper should be addressed to R. Y. K. Yang. whose current address is Department of Chemical Engineering, West Virginia University. Morgantown. WV 26506-6101. AIChE Journal February 1988with the notable exception of the first work, all these reactor schemes relied solely on diffusion as the means of contacting substrates and enzymes. Breslau and Kilcullen have suggested a number of HFER's in which the bulk flow is an important transport mechanism. Of great interest is the backflush mode of operating a HFER, in which substrates flow from the shell of a hollow-fiber cartridge to the lumina of the fibers, and enzymes are loaded into the sponge layers of the anisotropic ...

Study of enzymatic G6P synthesis using polymer‐bound ATP in membrane reactors

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“…An enzyme solution is ultrafiltered from the spongy side (porous substructure) of an asymmetric ultrafiltration membrane to the skin side; this introduces the enzymes in the spongy matrix. Feed solution is also supplied from the same side; product solution goes out through the membrane skin (see Jones et al 73 for a brief introduction to the literature of hollow fiber enzymatic reactors employing this method of immobilization). An example of this type of immobilization in the context of aqueousorganic enzymatic processing has been illustrated in section 2.4.4.…”

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