HYPERTHERMOPHILES AND THEIR POSSIBLE POTENTIAL IN BIOTECHNOLOGY

To develop novel processes in microbial biotechnology organisms with o utstanding properties are required. Archaea represent a nearly unexplo red third domain ('continent') of life, which harbours organisms livin g in extreme environments such as alkaline to acidic hot springs, anae robic sediments and highly saline environments. From high temperature terrestrial and marine biotopes many extreme heat-loving (hyperthermop hilic) Archaea and Bacteria have been isolated, which grow at temperat ures between 80 and 113 degrees C. Within the 16S rRNA-based phylogene tic tree of life, hyperthermophiles occupy the deepest phylogenetic br anches representing more than 30 genera. In their mode to gain energy, they exhibit a great variety: obligate chemolithoautotrophs utilizing only CO2, hydrogen, and different sulfur compounds are primary produc ers in hot and anaerobic environments. Organotrophs grow on organic ac ids, alcohols, sugars, amino acids, or polymers like starch or chitin. This diversity in combination with their unusual heat resistance make s hyperthermophiles appropriate for new biotechnological applications at high temperatures. After cloning the genes into easy cultivable mes ophiles, enzymes active at temperatures up to 130 degrees C are produc ed for food industry, biochemical and molecular research, or chemical industry. In addition, cultures can be applied directly in chemical pr ocesses like desulfurication of flue gases and in biohydrometallurgica l processes. (C) 1998 Elsevier Science B.V. All rights reserved.