Biocatalysis, the use of microbial cells or isolated enzymes in the production of fine chemicals, is steadily moving towards becoming accepted as an indispensable tool in the inventory of modern synthetic chemistry . It is estimated that in 10 % of the cases biocatalysis will provide an overall superior synthetic strategy over traditional organic chemistry . This remarkable development in a field coined “white biotechnology” is due to the growing recognition in the industry of the capabilities and performance of enzymes as exemplified in a growing number of implemented processes [3, 4], examples running at a scale of >1000 tons product/year. Breakthroughs in the key biotechnological areas of a) genetic resource access (explicitly the explorability of non-cultivated microorganisms), b) enzyme screening and discovery and c) in vitro evolution of proteins to find and optimize enzymes to become near-ideally suited biocatalysts have been instrumental in pushing industrial biocatalysis to where it stands today [5, 6]. With these technological options it seems that future use of biocatalysis is limited only by the availability of the biocatalyst , the screening for which is subject of this review.