Bremen 2000 – scientific programme
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EP: Extraterrestrische Physik
EP 13: Leben und Lebensbedingungen ausserhalb der Erde I
EP 13.7: Talk
Wednesday, March 22, 2000, 12:15–12:30, N3110
Cyanobacteria in extreme habitats — •Rajeshwar P. Sinha and Donat-Peter Häder — Institut für Botanik I, Staudtstr. 5, D-91058 Erlangen
Cyanobacteria play a vital role in aquatic as well as terrestrial ecosystems particularly in wetland rice paddy fields as a natural biofertilizer. Almost 2000 species of cyanobacteria can be found all over the world ranging from hot springs to Arctic and Antarctic regions. Cyanobacteria have developed effective protection strategies in response to extreme life conditions. Representatives of the genus Synechococcus and Mastigocladus for instance live in 73oC thermal water. Spirulina platensis is adapted to the high sodium carbonate concentrations of east African soda-lakes. To protect themselves from excessive solar radiation they produce screening pigments such as scytonemin and mycosporine- like amino acids or they store calcium carbonate inside their slime capsule. Most of the species produce special proteins (shock proteins), in response to high salinity or heat, in order to stabilize other cellular proteins and enzymes. Extreme physiological (stress) factors such as cold, drought, heat, salinity, and UV-B (280 – 315 nm) radiation play a key role in determining the growth and development of cyanobacterial populations in their natural habitats. Being cosmopolitan in distribution, cyanobacteria are thought to have been exposed to different levels and types of stresses during their development, thus providing a suitable system for analyzing the adaptive mechanisms developed in response to changing stress conditions.