Tolerance limits of methanogenic life in terrestrial permafrost

点击翻译按钮获取中文摘要

The evolution of life on Earth had already started 3.8 Ga ago, when living conditions on Mars were similar to those on early Earth. Assuming that first life on both planets was determined by complex microbial communities, the Martian life must have adapted to drastically changing environmental conditions or become extinct again. One possibility for survival of Martian primitive life might be subsurface lithoautotrophic ecosystems. Comparable environments exist in permafrost regions on Earth. Thus, terrestrial permafrost is considered to be a model for extraterrestrial analogue studies. The main objective of the planed project is to study tolerance limits of lithoautotrophic microorganisms derived from Siberian permafrost. Beside nitrifying bacteria, which show various adaptation strategies, primarily methanogenic archaea will be used, which show specific adaptations to the oxygen and organic free environment of early Earth. Tolerances of microbes within natural soils as well as pure bacterial cultures will be tested with regard to different stress factors. The borders of growth influenced by temperature extremes, desiccation, starvation and increased salt concentrations will be analyzed. The comparative system studies will serve to understand the modern Mars cryosphere and other extraterrestrial permafrost habitats. This knowledge represents an essential basis for searching and understanding of extraterrestrial life, if present, especially concerning possible protected niches on present Mars.