Conclusion Of Soil Temperature

It is possible that the ability of fungi to adapt to low and changing water activities, whether due to frigid temperatures or high salinities, is crucial for their successful survival in some of the harshest extreme environments on Earth. Since the majority of microbiological studies in the polar regions are oriented on the investigation of psychrophilic bacteria, the occurrence of fungi, one of the ecologically most successful eukaryotic lineages, has received little attention so far. However, fungi have been reported in connection with sub-Arctic vegetation, in soil and permafrost in polar regions, and recently found to occur abundantly below snow-covered tundra.

Subglacial environments constitute quite a unique ecosystem, since they enable on the geological scale, occasional enrichment of selected genotypes of the most robust species, able to tolerate a broad range of temperatures and water activities. Surprisingly, the deserts, glaciers and salterns may result in similar environmental and evolutionary pressure on microorganisms. Results of this study favour the hypothesis that fungal adaptation to low aw can be related to low temperature stress. Freezing, drying and hypersaline stress lead to cellular dehydration, and can therefore activate common responses. Cold-, salt- and drought-tolerant fungi may therefore belong to a limited group of extremophilic species that share more features and inhabit more extreme environments than we have imagined so far.

It seems that the occurrence of fungi in polar and other extreme natural environments has been largely underestimated, although these micro-eukaryotes can take up and transform nutrients very efficiently, and thus serve as a carbon sink and participate in the short food webs present. Our results indicate that subglacial environments may represent a significant, previously unrecognized reservoir not only of prokaryotic, but also of eukaryotic diversity. Fungi enclosed in ice will be released during periods of glacial melts and thus contribute to the biogeochemical processes and biodiversity in polar regions.

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