1. Instituto BIOFISIKA (UPV/EHU-CSIC), Department of Biochemistry and Molecular Biology, University of the Basque Country, PO Box 644, 48080 Bilbao, Spain
2. Department of Conservation of Natural Resources, Soil Microbial Ecology Group, NEIKER-Tecnalia, Berreaga 1, 48160 Derio, Spain