Enzyme Immobilisation Mini-Review

Introduction

Most chemical processes and reactions can be catalysed by enzymes and whole cells from microorganisms that contain enzymes. Such biocatalysts often offer better or potentially better alternatives compared to conventional chemical catalysts. The general advantages are that biocatalysts are highly efficient, environmentally acceptable, substrate-specific, and can work on a large range of reactions, including multi-step or more complex reactions, under mild conditions. The latter encourages energy efficiency in addition to rate efficiency. However, enzymes and cells may be unstable, inhibited by substrates or products, and difficult to handle and control, which thereby face limitations for use in industry. As such, the transformation of biocatalysed chemical processes from the laboratory to the industry, with an eye on commercial viability, is an essential work in the field of enzyme technology.

Due to the existing limitations of enzymes in their natural conditions, they often have to be artificially improved before their use in industrial processes. The engineering of enzymes for large-scale use as industrial catalysts is one main interesting, complex and interdisciplinary goal of biotechnology. It requires a multi-disciplinary utilisation of very different techniques, involving the screening of enzymes with suitable properties (1), and the improvement of enzyme properties via molecular biological techniques (2), immobilisation and post-immobilisation techniques (3,4), and reaction and reactor engineering (5).

For both technical and economic reasons, most chemical processes catalysed by enzymes require the continuous use or reuse of the biocatalyst for an extended period of time (6). Hence, enzyme stability, or the retention of enzyme activity over a reasonable timeframe, is a necessary criterion. All these factors can be provided by enzyme immobilisation on a suitable support structure. Enzymes are thus made to be physically confined or...