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Biogeosciences An interactive open-access journal of the European Geosciences Union
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Volume 8, issue 10
Biogeosciences, 8, 3041–3051, 2011
© Author(s) 2011. This work is distributed under
the Creative Commons Attribution 3.0 License.
Biogeosciences, 8, 3041–3051, 2011
© Author(s) 2011. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 31 Oct 2011

Research article | 31 Oct 2011

Distribution of typical denitrifying functional genes and diversity of the nirS-encoding bacterial community related to environmental characteristics of river sediments

S. Huang1, C. Chen1,2, X. Yang1, Q. Wu1, and R. Zhang1 S. Huang et al.
  • 1School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, Guangdong 510275, China
  • 2Department of Natural Resource Sciences, McGill University, Ste-Anne-de-Bellevue, Qecbec H9X 3V9, Canada

Abstract. Denitrification in river sediments leads to nitrate removal from the aquatic system; therefore, it is necessary to understand functional diversity of denitrifier communities in the system. Sediment samples (0–25 cm depth) were collected from three typical locations along the Pearl River. The real-time PCR approach was used to measure the abundance of nitrate (narG), nitrite (nirS, nirK and nrfA), and nitrous oxide (nosZ) reductase genes from the sediment samples. Assemblages of nirS, nirK and nosZ indicated that complete denitrification occurred in sediment cores, with the greatest number of gene copies from 5–15 cm depth. Dissimilatory nitrate reduction appeared to be important below 15 cm depth, based on increasing gene copies of narG and nrfA with sediment depth. There was a close match (78–94 %) between the nirS sequences recovered from the Pearl River sediment and those detected in estuarine and marine sediments as well as active sludge, suggesting that the nitrogen source in the Pearl River sediment was affected by domestic sewage inputs and irregular tides. Canonical correspondence analysis indicated that the spatial distribution of denitrifying bacteria was highly correlated with dissolved inorganic nitrogen (including NH4+, NO2 and NO3) concentrations in sediment. It was concluded that the difference in dissolved inorganic nitrogen concentrations along the sediment profile influenced the distribution of denitrifying genes and the nirS-encoding denitrifier community in the river sediment. In addition, a variety of novel denitrifying bacteria were revealed in the river sediment.

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