Abstract
The conditions for life as we know it will be defined. Also important terms such as prokaryotes, eukaryotes and microorganisms will be explained.
Microorganisms are the only organisms that are present everywhere on earth where life is possible; soil, water, animals and plants. Some microorganisms inhabit environments that humans would find too extreme for life. Such organisms are called extremophiles and the environment where they live are called extreme environments. Thus some organisms grow at high temperatures, others at low temperatures, at high pH or at low pH, at high pressure, at high salt concentrations or even at high radiation. The various environments and some of the organisms which are adapted to such environments will be described. The molecular basis for adaption to extreme environmens are known for some of these groups of organisms and will be explained. The use of extremophiles in biotechnology will be mentioned.