Degree Type


Date of Award


Degree Name

Master of Science


Ecology, Evolution, and Organismal Biology

First Advisor

Kirsten S. Hofmockel


Denitrification exhibits high spatial and temporal variability (Nunan et al., 2002), and, therefore, is difficult to predict. Since denitrifiers mediate denitrification, understanding the factors that influence the distribution of these microbes may help explain the variation observed in process rates. In this work I examined qnorB-bearing and nosZ-bearing denitrifiers and total bacteria, in terms of abundance in different soils. Denitrifying bacteria were described using genes that encode for the enzymes responsible for the production and reduction of N2O. Appropriate targets and methods for this were evaluated. An assessment was then carried out of how the distributions of these biological factors are affected by spatio-temporal differences of soil properties.

The seasonal variation in qnorB and nosZ abundance indicates a change in the genetic potential of the denitrifier community's ability to respond to fluctuations in soil resources. However, the abundance of nosZ only correlated to the inherent properties at landform scale, with unique parameters related to nosZ-bearing denitrifier being micronutrients and qnorB abundance. Of the soil properties measured, none consistently explained the pattern observed in gene abundance through time or space, except nitrogen and micronutrients. In addition, qnorB abundance did not correlate with the environmental gradients measured in this study, suggesting that other forms of physiological cues influence the distribution of this gene. These findings suggest that the variation detected in qnorB and nosZ abundance is dependent on physiological responces to either oxygen concentration or essential nutrients such as trace metals.


Copyright Owner

Alescia Ann Roberto



Date Available


File Format


File Size

118 pages