Masters of survival - Special characteristics of halobacteria from Permian salt
Vienna (FWF) - Some 200 to 250 million years ago the evaporation of the large Zechstein Sea resulted in the creation of numerous salt deposits which are still being exploited in Austria, e.g. in the Bad Ischl salt mine. These salt sediments contain microorganisms, which are estimated to be millions of years old. Why can such microorganisms survive for such a long time, given the extremely hostile environment? Sponsored by the Austrian Science Fund (FWF), Helga Stan-Lotter from the Institute of Genetics and General Biology at the University of Salzburg investigates and cultivates such halobacteria of different geographical origin. Her results are also of major interest for space research since there are indications of salt deposits on other planets as well, which opens up the theoretic possibility that Mars, for instance, might harbour at least bacterial life.
Helga Stan-Lotter cooperates with the Salinen Austria salt works, whose blasting operations for the extension of their underground salt tunnels provide a constant "fresh" supply of samples from depths of 600 - 700 metres. The miners also make drill cores from their exploratory borings for new salt deposits available to research. "These samples are very interesting - no human being has ever touched them before - sterile conditions are therefore an absolute must in order to avoid any contamination, e.g. with modern bacteria," explains Stan-Lotter. Since one of her project goals is the detailed investigation of the microbial populations in salt sediments of different geographical regions, she compares samples gathered from salt deposits in Austria, Germany, England and from the Salado Formation in New Mexico and Texas. It is important that they are of the same age, i.e. that they originated in the Permian, the youngest period of the Palaeozoic Era. Another aim is to isolate and cultivate the bacteria species detected and to determine whether they are related to any known halobacteria.
New species detected
The salt samples investigated contain an unexpectedly high number of different species of halobacteria. Stan-Lotter also found and isolated two new coccus-type species, which are similar to modern bacteria but have not been described yet. "This is a first indication that these bacteria can indeed survive for such a long time," explains Stan-Lotter. "We are hoping to be able to examine them using molecular biological techniques." The research efforts are also expected to shed light on the strategies responsible for the longevity of these organisms. Stan-Lotter: "Perhaps we'll find 'conservation molecules' whose properties we might be able to exploit." Model systems are therefore used to test suitable halobacteria for their reaction to starvation conditions and to determine their ability to survive in the absence of energy and food sources. "Our results are not only interesting for ourselves. Since Mars is known to have salt deposits, the question of whether this salt might enable microorganisms to survive so long even in an extraterrestrial environment also arises for NASA and ESA," says Stan-Lotter.
Prof. Helga Stan-Lotter
Institute of Genetics and General Biology, University of Salzburg
T +43 (0)662 8044 5756
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Vienna, 17 May 2002