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| Title: | Does Atmospheric NO3 Deposition Alter Actinobacterial Abundance and Community Composition in a Northern Hardwood Forest Ecosystem? |
| Authors: | Eisenlord, Sarah |
| Keywords: | actinobacterial
northern hardwood forest ecosystem |
| Issue Date: | 12-Aug-2008 |
| Abstract: | Atmospheric nitrogen deposition can alter the cycling of carbon in forest ecosystems by
slowing the microbially mediated decay of plant detritus, leading to the accumulation of
organic matter in surface soil and the greater leaching of dissolved organic carbon (DOC)
to ground and surface waters. However, we presently do not understand the microbial
mechanisms affected by atmospheric nitrogen deposition that regulate these
biogeochemical responses. Actinobacteria are one of the few groups of saprotrophic soil
microorganisms which degrade lignin, uniquely producing soluble polyphenolics which
can accumulate in the soil. The overall objective of this study was to examine the impact
of atmospheric NO3
- deposition on actinobacterial community composition and
subsequent effects on soil carbon cycling. To address this objective, actinobacterial
community structure was quantified in a large-scale field study in which atmospheric
NO3
- deposition has been experimentally increased for over a decade. Actinobacterial
abundance was assessed using quantitative PCR of 16S rDNA and community
composition was assessed though the compilation of clone libraries. Experimental
atmospheric NO3
- deposition had no effect on actinobacterial relative abundance in either
forest floor or surface mineral soil. However, there were significant differences in
community structure and the relative occurrence of key lignin degrading actinobacteria
families. Specifically, Streptomycetaceae and Micromonosporaceae, decreased in
occurrence under experimental NO3
- deposition in the surface soil, whereas the
occurrence of Streptomycetaceae in the forest floor increased under experimental NO3
-
deposition. Changes in the actinobacterial community composition appear to be one
mechanism contributing to the ecosystem-level biogeochemical changes in response to
increased nitrate deposition. |
| Appears in Collections: | Natural Resources and Environment, School of (SNRE)
Natural Resources and Environment, School of (SNRE)
Dissertations and Theses (Ph.D. and Master's)
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