Effect of environmental factors on nitric oxide reductase gene expression and denitrification in an agricultural soil



Shannon, Kelly Elizabeth Marion

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University of Guelph


Bacterial denitrification is an important process in the nitrogen cycle, contributing nitrous oxide to the atmosphere. This microcosm study quantified the effect of carbon and nitrate additions, and temperature on denitrification and the expression and abundance of 'Pseudomonas mandelii' and related species' nitric oxide reductase gene, ' cnorBp'. Glucose addition (500 [mu]g C g-1 soil) increased 'cnorBp' expression and abundance, and denitrification. Increased nitrate addition (0-500 [mu]g N g-1 soil) increased denitrification, but did not increase 'cnorB p' expression and abundance in all cases. Soils incubated at 15 and 22°C had increased denitrification and 'cnorBp' expression and abundance, compared with soils incubated at 4 and 8°C. Although a correlation was determined between 'cnorBp' expression and denitrification, under some conditions increased 'cnorB p' expression did not cause increased denitrification. This study provided a better understanding of the relationships between denitrifier activity, abundance, and denitrification, and how these parameters responded to different environmental conditions.



agricultural soil, environmental factors, nitric oxide, reductase gene expression, denitrification