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 characteri stics 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 relativ ely small element of total production costs for most of the processes that have achieved commercial success. This paper attempts to identify some of t he factors necessary for success and to give illustrative examples. These i nclude improved process integration and downstream processing with a proper appreciation that the patentability and cost of the product are of vital i mportance. Screening is highlighted as Very important in achieving successf ul processes, including the consideration of plant sources of enzymes as wo rthwhile. Because biocatalyst success is closely linked with how high a con centration of product can be made, the importance of finding or designing b iocatalysts with increased resistance to product inhibition should be stron gly 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.