Abundances and potential activities of nitrogen cycling microbial communities along a chronosequence of a glacier forefield

• Published in: The ISME Journal Vol. 5; no. 6; pp. 1025 - 1037
• Main Authors: Brankatschk, Robert, Töwe, Stefanie, Kleineidam, Kristina, Schloter, Michael, Zeyer, Josef
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.06.2011; Oxford University Press; Nature Publishing Group
• Subjects: 631/326/2565/855; 631/326/325; 631/326/47; Abundance; Archaea - genetics; Archaea - metabolism; Bacteria - enzymology; Bacteria - genetics; Bacteria - metabolism; Biomedical and Life Sciences; copy number; Decomposition; Denitrification; Ecology; Ecosystem; Enzymatic activity; Enzymes; Evolutionary Biology; Glaciers; Ice; Ice Cover - microbiology; Life Sciences; Microbial activity; Microbial Ecology; Microbial Genetics and Genomics; Microbiology; Microorganisms; Mineralization; Nitrification; Nitrogen; Nitrogen - metabolism; Nitrogen cycle; Nitrogen Fixation; Nutrient cycles; Original; original-article; Plants - metabolism; Proteolysis; Soil; Soil - chemistry; Soil formation; Soil Microbiology; Soil microorganisms; Soils; Switzerland; functional genes; real-time PCR; chronosequence; nitrogen cycle; soil development
• ISSN: 1751-7362; 1751-7370; 1751-7370
• DOI: 10.1038/ismej.2010.184

Glacier forefields are ideal ecosystems to study the development of nutrient cycles as well as single turnover processes during soil development. In this study, we examined the ecology of the microbial nitrogen (N) cycle in bulk soil samples from a chronosequence of the Damma glacier, Switzerland. Major processes of the N cycle were reconstructed on the genetic as well as the potential enzyme activity level at sites of the chronosequence that have been ice-free for 10, 50, 70, 120 and 2000 years. In our study, we focused on N fixation, mineralization (chitinolysis and proteolysis), nitrification and denitrification. Our results suggest that mineralization, mainly the decomposition of deposited organic material, was the main driver for N turnover in initial soils, that is, ice-free for 10 years. Transient soils being ice-free for 50 and 70 years were characterized by a high abundance of N fixing microorganisms. In developed soils, ice-free for 120 and 2000 years, significant rates of nitrification and denitrification were measured. Surprisingly, copy numbers of the respective functional genes encoding the corresponding enzymes were already high in the initial phase of soil development. This clearly indicates that the genetic potential is not the driver for certain functional traits in the initial phase of soil formation but rather a well-balanced expression of the respective genes coding for selected functions.