Microbial activity and diversity during extreme freeze-thaw cycles in periglacial soils, 5400 m elevation, Cordillera Vilcanota, Perú

• Published in: Extremophiles : life under extreme conditions Vol. 13; no. 5; pp. 807 - 816
• Main Authors: Schmidt, S. K, Nemergut, D. R, Miller, A. E, Freeman, K. R, King, A. J, Seimon, A
• Format: Journal Article
• Language: English
• Published: Japan Japan : Springer Japan 01-09-2009; Springer Japan; Springer; Springer Nature B.V
• Subjects: Animal, plant and microbial ecology; Bacteria; Bacteria - classification; Bacteria - genetics; Bacteria - isolation & purification; Bacteria - metabolism; Betaproteobacteria - classification; Betaproteobacteria - genetics; Betaproteobacteria - isolation & purification; Betaproteobacteria - metabolism; Biochemistry; Biodiversity; Biological and medical sciences; Biomass; Biomedical and Life Sciences; Biotechnology; Carbon - metabolism; Cold Climate; Cyanobacteria - classification; Cyanobacteria - genetics; Cyanobacteria - isolation & purification; Cyanobacteria - metabolism; DNA, Bacterial - genetics; DNA, Bacterial - isolation & purification; Elevation; Freezing; Fundamental and applied biological sciences. Psychology; Glutamic Acid - metabolism; Ice caps; Ice Cover - microbiology; Life Sciences; Microbial activity; Microbial corrosion; Microbial Ecology; Microbiology; Nitrogen - metabolism; Original Paper; Peru; Phylogeny; Polar environments; Soil; Soil Microbiology; Soil temperature; Soils; Space life sciences; South America; Peru; America; Unvegetated soils; Freeze–thaw cycles; Freezing rates; Glacial retreat; Microbial activity; Tropical zone; Environmental factor; Climatic zone; Freeze-thaw cycles; Freeze thaw cycle; Soils; Polar region; Extreme environment; Altitude
• ISSN: 1431-0651; 1433-4909
• DOI: 10.1007/s00792-009-0268-9

High-elevation periglacial soils are among the most extreme soil systems on Earth and may be good analogs for the polar regions of Mars where oligotrophic mineral soils abut with polar ice caps. Here we report on preliminary studies carried out during an expedition to an area where recent glacial retreat has exposed porous mineral soils to extreme, daily freeze-thaw cycles and high UV fluxes. We used in situ methods to show that inorganic nitrogen (NO₃ ⁻ and NH₄ ⁺) was being actively cycled even during a period when diurnal soil temperatures (5 cm depth) ranged from -12 to 27°C and when sub-zero, soil cooling rates reached 1.8°C h⁻¹ (the most rapid soil cooling rates recorded to date). Furthermore, phylogenetic analyses of microbial phylotypes present at our highest sites (5410 m above sea level) showed the presence of nitrifying bacteria of the genus Nitrospira and newly discovered nitrite-oxidizing Betaproteobacteria. These soils were overwhelmingly dominated (>70% of phylotypes) by photosynthetic bacteria that were related to novel cyanobacteria previously found almost exclusively in other plant-free, high-elevation soils. We also demonstrated that soils from our highest sites had higher potential for mineralizing glutamate and higher microbial biomass than lower elevation soils that had been more recently covered by ice. Overall, our findings indicate that a diverse and robustly functioning microbial ecosystem is present in these previously unstudied high-elevation soils.