1. Department of Medical Microbiology, University of Groningen, University Medical Center Groningen, Hanzeplein 1, Groningen 9700 RB, The Netherlands
2. DSM Biotechnology Center, Alexander Fleminglaan 1, Delft 2613 AX, Netherlands
3. Department of Biosystems Science and Engineering, ETH Zurich, Mattenstrasse 26, Basel 4058, Switzerland
4. FGen AG, Hochbergerstrasse 60C, Basel 4057, Switzerland