Extremophiles

, Volume 13, Issue 5, pp 807–816

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

  • S. K. Schmidt
  • D. R. Nemergut
  • A. E. Miller
  • K. R. Freeman
  • A. J. King
  • A. Seimon
Original Paper

DOI: 10.1007/s00792-009-0268-9

Cite this article as:
Schmidt, S.K., Nemergut, D.R., Miller, A.E. et al. Extremophiles (2009) 13: 807. doi:10.1007/s00792-009-0268-9

Abstract

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.

Keywords

Freeze–thaw cyclesFreezing ratesGlacial retreatUnvegetated soils

Copyright information

© Springer 2009

Authors and Affiliations

  • S. K. Schmidt
    • 1
  • D. R. Nemergut
    • 2
    • 3
  • A. E. Miller
    • 4
    • 2
  • K. R. Freeman
    • 1
  • A. J. King
    • 1
  • A. Seimon
    • 5
  1. 1.Department of Ecology and Evolutionary BiologyUniversity of ColoradoBoulderUSA
  2. 2.Institute of Arctic and Alpine ResearchUniversity of ColoradoBoulderUSA
  3. 3.Environmental Studies ProgramUniversity of ColoradoBoulderUSA
  4. 4.National Park ServiceAnchorageUSA
  5. 5.Wildlife Conservation SocietyBronxUSA