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U.S. Department of Energy Office of Biological and Environmental Research

PI-Submitted Research Highlights for
Terrestrial Ecosystem Science Program

Temperature Sensitivity of Deep Peat Microbial Enzymes

Christopher W. Schadt

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27 July 2018

Stable temperatures in peat at depth appear to result in microbial community containing enzymes with lower sensitivity or responsiveness to temperature increases.

The Science
This study provides an improved understanding of the microbial mechanisms contributing to peat decomposition, reducing uncertainty around carbon cycling in these systems; however, results also suggest the potential for uncoupling of the nitrogen and carbon cycles as these environments evolve over time.

The Impact
There are large uncertainties about the fate of carbon stored in deep peat deposits under the changing environment. Understanding how microorganisms affect the decomposition of these deposits under varying conditions should help reduce this uncertainty.

Summary
Scientists from Oak Ridge National Laboratory hypothesized that the more stable recalcitrant subsurface environment would contain a smaller, less diverse microbial enzyme pool that is better adapted to a narrow temperature range. Potential enzyme activity decreased with peat depth as expected and corresponded with changes in peat composition and microbial biomass. Enzyme activation energy decreased with depth as predicted; however, leucine amino peptidase activation energy was much lower than other enzymes, suggesting a limited ability for these nitrogen-acquiring enzymes to increase activity with increased temperatures. Stable temperatures at depth in the peat appear to result in a microbial community containing enzymes that have lower sensitivity or responsiveness to temperature increases.

Contacts
BER Program Manager
Daniel Stover 
Terrestrial Ecosystem Science, SC-23.1
Daniel.Stover@science.doe.gov

Principal Investigator
Christopher W. Schadt
Senior Staff Scientist
Oak Ridge National Laboratory
Oak Ridge, TN 37831
schadtcw@ornl.gov

Funding
Supported by the Terrestrial Ecosystem Science (TES) program as part of the Oak Ridge National Laboratory (ORNL) SPRUCE project under the TES Scientific Focus Area (SFA) through the Office of Biological and Environmental Research (BER), within the U.S. Department of Energy Office of Science, and by a university-led project of The Georgia Institute of Technology (grant number # DE-SC0012088).

Publications
Steinweg, J.M., J.E. Kostka, P.J. Hanson, and C.W. Schadt. “Temperature sensitivity of extracellular enzymes differs with peat depth but not with season in an ombrotrophic bog.” Soil Biology and Biochemistry 125, 244–250 (2018). [DOI:10.1016/j.soilbio.2018.07.001]

Related Links
http://mnspruce.ornl.gov

Oak Ridge National Laboratory (TES SFA)

Georgia Institute of Technology (DE-SC0012088)

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