Extremophilic microorganisms

In this lecture, Dr Helga Stan-Lotter from the University of Salzburg, discusses extreme environments. These are characterized by physical and chemical parameters which were considered lying outside the range which is suitable for life. In recent years, the notion of what constitutes life-limiting conditions in an environment has undergone dramatic changes: microorganisms and occasionally higher organisms were discovered, which not only tolerate, but thrive under ranges of temperatures, pH values, pressures, salinity, ionizing radiation etc. previously thought to destruct biomolecules and organisms.
Some of the mechanisms responsible for these life styles are in the process of being elucidated. The presence of liquid water is a prerequisite for growth under all kinds of conditions; however, survival of resting stages, such as spores or dormant forms, was shown to occur in vacuum and in space conditions for several months.
The detection of numerous viable prokaryotes and spores in subterranean locations, such as basalt, granite, ancient halite and sediments, suggests the possibility of extensive longevity, perhaps over millions of years. The implications of these discoveries for the search for extraterrestrial life are several-fold: the probability of finding prokaryotic life in environments such as the subsurface of Mars or the salty ocean of the Jovian moon Europa appears greatly enhanced, and the potential for panspermia is considered more plausible than ever before.