Peter Samuel James Cheetham

Screening for novel biocatalysts

Abstract This review attempts to demonstrate the importance of goal-orientated screening for new biocatalysts. Examples of enzymes and microorganisms that have been developed and that have acquired commercial applications are described so as to illustrate the technological potential of biocatalysts. A survey of screening techniques and recently reported examples of screening from food, chemical, pharmaceutical and waste disposal applications etc. are also presented to demonstrate the feasibility of this approach for generating new biocatalysts. An appreciation of some of the difficulties involved, the achievements of Japanese researchers and some examples of the cornucopia of largely unrecognized and potentially valuable microbial activities are also given. An increased effort in screening would have the following benefits: an increased range of biocatalysts with different enzyme activities would be available and more biocatalysts with improved characteristics, suitable for use under industrial conditions, such as resistance to elevated temperatures, extremes of pH and organic solvents would be discovered. Secondly the manpower and other resources required to carry out screening programmes would be reduced, for instance by developing automated techniques. Thirdly, screening procedures would be made much more accessible to non-specialists. Fourthly, improved efforts and expertise in screening would supplement other emerging techniques such as protein engineering. The development of selective, non-random, goal-orientated screening techniques, methods of evaluating biocatalyst performance under operational conditions, and an approach that is more orientated towards commercially desirable goals are essential if these objectives are to be achieved. Screening of naturally occurring microorganisms still appears to be the best way to obtain new strains and/or enzymes for commercial applications. However, two major problems appear to exist. Firstly in identifying applications that are technically feasible and that have sufficient commercial potential to justify the research and development required to generate a new commercially viable biocatalyst and secondly the relatively small number of scientists outside Japan with skill and experience in screening for biocatalysts.

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.

Production of Isomaltulose Using Immobilized Bacterial Cells

Publisher Summary This chapter describes the importance of isomaltulose as a product and the attractions of using an immobilized cell process for its production. It describes some of the methodological advances made and the experimental approaches useful for its large-scale production process. The chapter discusses the method to produce a pure, cheap product in as great a yield as possible and compatible with easy operation of the process. Isomaltulose is a natural component of honey. It has a number of interesting properties. The chemical synthesis of isomaltulose is very difficult. The microbial formation of isomaltulose has attracted commercial interest for some time. Efforts have been made to produce isomaltulose using immobilized cells as they offer several potential advantages over the fermentation process. Isomaltulose formation takes place most efficiently when nongrowing cells are used. Therefore, the cell production and product formation steps can be individually optimized, because they are performed separately.

Enzymes, for Flavor Production

Introduction History Some Characteristic Features of Food Biotechnology Market Need Bioprocesses to Make Flavor and Aroma Chemicals Important Considerations in Developing a Successful Process Key Performance Parameters Technicocommercial Factors Protection of Technological Advantages Categorization of Bioflavor Processes Examples of Actual Bioflavor Processes The Application of Genetic Engineering Techniques to the Production of Bioflavors Downstream Processing Chromatography Cell Disruption Centrifugation Other Considerations Comparison of Different Processes Flavor Applications Constraints Product Approval and Registration Consumer Approval Future Opportunities Conclusions Bibliography Keywords: bioactive molecules; biocatalysis; downstream processing; fermentation; isolated enzymes; natural flavoring substances; nature-identical flavoring substances; receptor