1. Department of Chemistry, University of Helsinki, P.O. Box 55, A. I. Virtasen Aukio 1, Helsinki FI-00014, Finland
2. Department of Microbiology, University of Helsinki, P.O. Box 56, Viikinkaari 9, Helsinki FI-00014, Finland
3. Department of Bioproducts and Biosystems, Aalto University, Vuorimiehentie 1, Espoo FI-02150, Finland