1. Institute of Genetics and General Biology, Hellbrunnerstr. 34, A- 5020 Salzburg, Austria1
2. Dept of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK2
3. Institute of Microbiology and Genetics, University of Vienna, Dr Bohrgasse 9,A-1030 Vienna, Austria3
4. Department of Microbiology, University of Regensburg, Universit ätsstraße 31, D-93053 Regensburg , Germany4
5. Botanical Institute of the University of Munich, Menzinger Str. 67, D-80638 Munich, Germany5