What makes a good biocatalyst?

A biocatalyst is an enzyme or cell with both the required activity in high enough levels to make its use cost-effective, and also the other characteristics necessary for its successful and cost-effective use on an industrial scale. The biocatalyst is usually the lynchpin of a process, without which the product could not be made, despite the biocatalyst being only a relatively small element of total production costs for most of the processes that have achieved commercial success. This paper attempts to identify some of the factors necessary for success and to give illustrative examples. These include improved process integration and downstream processing with a proper appreciation that the patentability and cost of the product are of vital importance. Screening is highlighted as Very important in achieving successful processes, including the consideration of plant sources of enzymes as worthwhile. Because biocatalyst success is closely linked with how high a concentration of product can be made, the importance of finding or designing biocatalysts with increased resistance to product inhibition should be strongly encouraged especially as so little research effort has been carried out in this area so far. (C) 1998 Elsevier Science B.V. All rights reserved.