Affiliation: | Institute of Terrestrial Ecology, Merlewood Research Station, Windermere Road, Grange-over-Sands, Cumbria LA11 6JU, UK;Microbial Ecology, Department of Ecology, Helgonavägan 5, S-223 62 Lund, Sweden;Department of Genetics &Microbiology, University of Liverpool, P.O. Box 147, Liverpool L69 3BX, UK |