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FEMS MicrobiologyReviews75 (1990) 103, 104 Publishedby Elsevier 103 FEMSRE00151 Editorial Adaptation of microorganisms to extreme environments R.A. Prins, W. de Vrij, J.C. Gottschal and Th.A. Hansen A workshop under the above title was held in June 1989 at the Biological Centre in Haren of the University of Groningen, The Netherlands. The workshop was organized by the Royal Netherlands Academy ol Arts and Sciences (Biology Council) and the Department of Microbiology zr Haren and sponsored by the biotechnology industry, various scientific foundations and the Ur~ivcrsity of Groningen. All participants were invited on the basis of their interest and active research in the field of 'extremophiles'. Our knowledge of biology in the past has largely been determined by the results of research on organisms living and functioning in environments characterized by moderate physieo-ehemieal prc,perties. An anthropocentric approach is the basis for the contents of the term 'moderate'. Temperature, heavy metal concentrations, contents of salts and nutrients, pH, pressure oxygen and water concentrations of the habitats studied were most often in a range considered 'normal' for living organisms. A considerable part of our insight in the functioning of the cell has been based on observations of cells functioning optimally at a pressure of 1 arm, at near neutral pH, and in an isotonic solution having a temperature of 30370C. Recently, microorganisms have been discovered that appear to live in habitats which can be considered as extreme on the basis of the prevailing environmental conditions. At an increased rate such microorganisms are isolated from the most diverse and bizarre environments: hot deserts, frozen soils and rocks in the ~'alleys of Antarctica, hot sulphurous springs on Iceland, Italian solfatao ras, the deep sea with its cold seeps and black smokers, alkaline lakes in Egypt and Central Africa, extremely acidic environments like the seepage of ores and mine-refuse piles, natural salt lakes, artificial saltpans or even salt crystals in which microorganisms have been trapped for some 200 w2llion years. Throughout such studies it has repeatedly been demonstrated that the boundaries and borderlines in our thinking about the conditions which allow life on earth have to be enlarged. Not only are these organisms found in places often considered empty in the biological sense, it also is clear that these microbes have developed numerous special adaptations to survive in extreme habitats. Among these adaptations are: new mechanisms for energy transduction and for the regulation of the intracellular environment and metabolism, new biochemical answers to problems concerning the stability of structural and functional components of the cell membrane and the cell wall or concerning the functioning of coenzymes. The results of research on these themes are of considerable importance to microbiology as well as to biology in general. New and highly original techniques are also needed to study the "extremophiles'. Experimental procedures during sampling, culturing, choice of materials and preparatory techniques often are as extreme as the habitats studied. Another aspect of this field is its obvious multidisciplinary character as the studies call for a permanent dialogue between microbiologists, geoehemists, biochemists and physicists. A further deepening of biological research on extremophilic organisms is of particular importance for our understanding of the eady evolution of prokaryotes, the relation between 0168-6445/90/$03.50 © t990 Federationof European MicrobiologicalSocieties 104 structure and function of cell components and enzymes, the evolution of survival strategies, mechanisms of energy transduction and conservation, while its significance for biotcchnology is thought to be enormous. In the seven sessions of the workshop (thermophiles, general adaptive properties of thermophiles, biochemistry of thermophiles, osmoregulation, alkaliphiles, acidophiles, and applications), twenty-two invited speakers reviewed their re- search results and presented an overview of the present knowlegde in their field of interest as introductions to the discussions. Some forty posters were ~resented. The organizers are grateful to Professor G. Gottschalk, the Editor-in-Chief of FEMS Microbiology Reviews, for his offer to publish the manuscripts of most of the introductory lectures of the workshop in this journal.