AbstractCover illustration: In order to use rapeseed oil for e.g. biofuels, biocatalysts are needed for processing. Expanding the former limits of biocatalytic applications is the theme of this special issue of BTJ, edited by Dietmar Haltrich (Vienna, Austria) and Mikhail Rabinovich (Moscow, Russia). Highlights include protein engineering based on rational design or random mutagenesis, as well as enzyme adaptation for functioning in novel solvents including ionic liquids. Image of butterly on rapeseed field: courtesy of Jens Bredehorn (www.pixelio.de).