1. Institute of Applied Biology, Faculty of Medical and Life Sciences, Furtwangen University, 78054 VS-Schwenningen, Germany
2. Institute of Bioprocess and Biosystems Engineering, Hamburg University of Technology, 21073 Hamburg, Germany
3. s&h Ingenieurgesellschaft mbH, 21109 Hamburg, Germany
4. Department of Biochemical Engineering, University College London, London WC1H 0AH, UK