1. Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9751 NN Haren,1
2. Genencor International, 2600 AP Delft,2 and
3. Institut für Mikrobiologie, Johann-Wolfgang- Goethe-Universität Frankfurt, D 60439 Frankfurt am Main, Germany3
4. Department of Pharmaceutical Biology, University of Groningen, 9713 GZ Groningen,4 The Netherlands, and