Cold adapted microorganisms, plants and animals are widely distributed in nature since more than 80% of the biosphere show temperatures below soc. These organ­ isms playa major role in the processes of nutrient turnover and primary biomass production in cold ecosystems and have adapted to their environment in such a way that metabolic processes, reproduction and survival strategies are optimal. Cold adapted organisms have received little attention so far. Only within the past few years it has been recognized that these organisms and their products provide a large potential for biotechnological applications. Biochemical reactions can be per­ formed at low temperatures and terminated by mild heat treatment, without the risk of contaminations by mesophiles or thermophiles. Thus, the practical utiliza­ tion of cold-adapted organisms would constitute a considerable progress towards the saving of energy. In this book, prominent authors from industries and universities present new concepts and developments. Their articles summarize the actual and potential applications of cold-adapted organisms and viruses in several fields of biotechnol­ ogy, such as enzymes, health, food, agriculture and environment. Further chapters cover the application of cold-adapted microorganisms for bio-mining and as genetic tools. We are most grateful to the authors for their excellent contributions, to Brigitte Marschall and Alexander Koren (vanillapaint) for skilful preparation of the layout, and to the publishers, especially to Dr. Dieter Czeschlik, for their cooperation.