This book is based on papers presented at an IUBS/IUMS workshop on Microorganisms and the Maintenance of Biodiversity, held at Egham in 1993. Over 30 contributors cover a wide range of topics, including: the extent of microbial diversity; the impact of microorganisms on global ecology and nutrient cycling, microorganisms and ecosystem maintenance, inventorying and monitoring microorganisms and the microbiology resource base.