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Harvard Forest Symposium Abstract 2015

  • Title: Quantitative real time PCR analyses reveal changes in the soil nitrifier and denitrifier bacterial gene copy numbers in long-term N- amended sites of Harvard Forest, MA, USA
  • Primary Author: Swathi Turlapati (University of New Hampshire - Main Campus)
  • Additional Authors: Rakesh MInocha (USDA Forest Service); Subhash Minocha (Not Specified); Karen Sweeney (Not Specified); Louis Tisa (Not Specified)
  • Abstract:

    The changes in population densities of the bacterial N-cycling genes were studied in response to two decades of N amendment in the soil organic and mineral horizon at Harvard Forest, MA. Quantitative Real Time Polymerase Chain Reaction (QPCR) analyses were used to evaluate changes in copy numbers of ammonia monooxygenase (amoA) gene representing the nitrifier community and nitrite reductase (nirS) along with nitrous oxide reductase (nosZ) genes from denitrifier community. Thirty soil samples (3 treatments x 5 subplots per treatment x 2 soil horizons) were collected in September 2009 from untreated control, low N (LN, 50 kg of NH4NO3 ha-1 year-1), and high N (HN, 150 kg of NH4NO3 ha-1 year-1) plots. Relative to the controls gene copies were higher in HN mineral soil for amoA and in LN organic soil for nosZ. Soil total C, NO3- and NH4+ were found to positively influence the amoA gene abundance in mineral soil. Total N and Mg2+ were found to be positively correlated to mineral soil nirS genes. The amoA and nirS sequences cloned from these soils matched closely with genera; Nitrosospira (amoA) and Pseudomonas (nirS). Oligotyping analysis conducted with the 102 amoA clone sequences from this study identified 52 different oligotypes; 30 of these were unique to HN-organic and 19 to HN-mineral soils with only 3 being common to both horizons. This revealed distinct nitrifier communities for organic and mineral horizon.











  • Research Category: Large Experiments and Permanent Plot Studies
    Physiological Ecology, Population Dynamics, and Species Interactions

  • Figures:
  • Turlapati et al. Figures.pdf
    Turlapati et al. Table.pdf