1. Department of Agriculture, Food and Environment; University of Catania; Via Santa Sofia, 100 95123 Catania Italy
2. Science and Technology Park of Sicily; Z.I. Blocco Palma I; Str.le Lancia 57 95121 Catania Italy
3. Department of Genetechnology/Microbiology; Faculty of Biology; University of Bielefeld; 33501 Bielefeld Germany