The use of enzymes employed either as isolated enzymes, crude protein extracts or whole cells for the transformation of non-natural organic c- pounds is not an invention of the twentieth century: they have been used for more than one hundred years. However, the object of most of the early research was totally different from that of the present day. Whereas the elucidation of biochemical pathways and enzyme mechanisms was the main driving force for the early studies, in contrast it was mainly during the 1980s that the enormous potential of applying natural catalysts to transform non-natural...