1. Natural Products Laboratory, Institute of Biology (Y.H.C., Y.D., M.V., R.V.), Leiden University, 2300 RA Leiden, The Netherlands; and Laboratory for Process Equipment (Y.H.C., J.v.S., G.-J.W.) and Biocatalysis and Organic Chemistry Group, Department of Biotechnology (F.H., I.W.C.E.A.), Delft University of Technology, 2628 CA Delft, The Netherlands