The term biocatalyst can refer to enzymes in various forms which are pure enzymes crude enzymes, immobilised enzymes, whole cell, immobilised whole cell, catalytic antibodies, designer enzymes and recently cross-linked enzyme crystals. The employment of enzymes and whole cells have been important for many industries especially for centuries in the food & drink businesses where the production of wine, beer & cheese is dependent on the effects of the microorganisms. Biocatalysis has wide applications to produce fine chemicals, especially for the pharmaceutical industry. The biggest advance in biotransformation operation has to be recombinant DNA technology. Not only is it possible to over express particular genes but it is also possible to express them in another organism, or to create unique catalysts. For example, a plasmid containing genes over expressing trehalase has been inserted into Escherichia coli. The enzyme accumulated in the periplasm of the Escherichia coli and this made it easy to extract it by osmotic shock . It is now anticipated that within a few years more than half the world's enzymes will be produced commercially using recombinant DNA technology.