The overall aim of this book is to provide a comprehensive review of the current understanding of the mechanisms that the micro-organisms known as extremophiles have evolved to survive and grow in particular extreme environments, and how these may be, or are being, exploited for biotechnological processes. Whilst the volume is aimed primarily at established research workers in universities, research institutes and industry, it is hoped that it will also provide a stimulating introduction to the subject for senior undergraduates and postgraduates who are interested in organisms which inhabit unusual and extreme environments. In future years these organisms may form the basis of new biotechnologically-based industries.