This review examines the strengths and weaknesses of immobilisation when used as a technique for deploying enzymes and cells in systems .Suitable methods for preparing immobilised conjugatcs are described ; the potcntial benefits of immobilisation for industrial products. analysis and academic studies are discussed..

Immobilised biocatalysts—a critical review

Publisher Summary This chapter discusses immobilized living cells, their advantages, and their applications in industry. Over the past two decades, there have been rapid developments in the use of enzymes as catalysts for industrial, analytical, and medical purposes and a new field of research called enzyme technology. Current and industrial applications of continuous single-enzyme reactions are carried out using immobilized microbial cells. Immobilized living cells should be preferred to immobilized enzymes for degradative and synthetic reactions in industry; another major advantage of immobilized cells is that the operational stability of the immobilized living cells may often be greatly enhanced by the regeneration of the enzyme activities of the immobilized cells. The use of immobilized cells enables greater control throughout the reaction. The applications of immobilized living cells are not limited to the production of chemical fermentation products but have been extended to the production of viral particles or synchronous cells, the chromatographic separation of special cells, the culturing of animal tissue, and, more recently, the immobilization and use of plant cells in the production of alkaloids.

Immobilized Living Cells and Their Applications

This chapter begins with a brief overview of the typical polymeric materials used for bead creation and their limitations. A full description is then provided of procedures to construct different bead forms, e.g., from cylindrical to almost perfectly spherical, by changing both the molds and the media into which the molten or dissolved hydrocolloid preparation is dropped or transferred. Also, some information on dropping methods, changing drop size and distribution, and liquid sprays is provided, affording a measure of control over bead size and distribution. The various water-soluble polymers that can be used for bead formation are discussed at length. The properties of gel beads prepared from agar/agarose ?-carrageenan, alginate, celluloses, chitosan, and to a lesser extent polyacrylamide and other synthetic polymers, among many others, are described. The use of crosslinking agents for both creation and strengthening of several bead types is thoroughly covered. Special methods to modify the porosity of the formed beads are also described, as are methods of slow dissolution of crystals by acid to facilitate better growth of embedded cells via pH regulation. A special section is devoted to beads prepared from proteins, ways to increase their stability (with, for example, glutaraldehyde), and their influence on the cells embedded within them. Since a combination of alternative methods may well provide a good means of overcoming the evident shortcomings of current bead-formation techniques, at the end of this chapter, a few approaches are presented, such as adding epoxy- resin reagent and curing agent to alginate for matrix stabilization, and other less known approaches for bead stabilization, as well as less traditional ways of producing and modifying beads.

Bead Formation, Strengthening, and Modification

The oxidation of 6- and 7-aryl-4(3h)-pteridinones by immobilized arthrobacter M-4 cells containing xanthine oxidase

A method is described for the oxidation of some 1-alkyl-3-carbamoylpyridinium chlorides by reaction with immobilized rabbit liver aldehyde oxidase. With the 1-methyl-, 1-ethyl-and 1-n-propyl derivatives, only the 1-alkyl-1,6-dihydro-6-oxo-3-pyridinecarboxamides have been obtained, but with the t-Bu analogue the corresponding 4-oxo compound was found as single product. The i-Pr derivative gave rise to a mixture of the corresponding 4- and 6-oxo compounds. From the kinetic data some information has been acquired with respect to the enzyme active-site environment and the binding of the substrates to the enzyme.

The use of immobilized enzymes in organic synthesis. Part 6. Oxidation of 1‐alkyl‐3‐carbamoylpyridinium chlorides by rabbit liver aldehyde oxidase

Cells of Arthrobacter X-4 were immobilized by entrapment in gelatin crosslinked with glutaraldehyde. The xanthine oxidase activity and stability were determined at various temperatures. In comparison with bovine milk xanthine oxidase the bacterial enzyme is more stable and has a different substrate specificity. 1-Methylxanthine was oxidized on a preparative scale.

Xanthine Oxidase Activity of Arthrobacter X-4 cells Immobilized in Glutaraldehyde-Crosslinked Gelatin

Xanthine Oxidase Activity of Arthrobacter X-4 Cells etc

Milk or a solution of gelatin and milk or commercial xanthine oxidase were lyophilized and the powdered freeze-dried materials crosslinked with glutaraldehyde. The resulting immobilized xanthine oxidase preparations have a good stability, are highly active and well suited for organic synthesis.

H.C. van der Plas

Papers

Xanthine Oxidase Activity of Arthrobacter X-4 cells Immobilized in Glutaraldehyde-Crosslinked Gelatin

Xanthine Oxidase Activity of Arthrobacter X-4 Cells etc

Direct immobilization of milk xanthine oxidase in milk protein with and without addition of gelatin