Changes in benthic denitrification, nitrate ammonification, and anammox process rates and nitrate and nitrite reductase gene abundances along an estuarine nutrient gradient (the Colne estuary, United Kingdom)

Dong, Liang F. and Smith, Cindy J. and Papaspyrou, Sokratis and Stott, Andrew and Osborn, A. Mark and Nedwell, David B. (2009) Changes in benthic denitrification, nitrate ammonification, and anammox process rates and nitrate and nitrite reductase gene abundances along an estuarine nutrient gradient (the Colne estuary, United Kingdom). Applied and Environmental Microbiology, 75 (10). pp. 3171-3179. ISSN 0099-2240

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Abstract

Estuarine sediments are the location for significant bacterial removal of anthropogenically derived inorganic nitrogen, in particular nitrate, from the aquatic environment. In this study, rates of benthic denitrification (DN), dissimilatory nitrate reduction to ammonium (DNRA), and anammox (AN) at three sites along a nitrate concentration gradient in the Colne estuary, United Kingdom, were determined, and the numbers of functional genes (narG, napA, nirS, and nrfA) and corresponding transcripts encoding enzymes mediating nitrate reduction were determined by reverse transcription-quantitative PCR. In situ rates of DN and DNRA decreased toward the estuary mouth, with the findings from slurry experiments suggesting that the potential for DNRA increased while the DN potential decreased as nitrate concentrations declined. AN was detected only at the estuary head, accounting for �30 of N 2 formation, with 16S rRNA genes from anammox-related bacteria also detected only at this site. Numbers of narG genes declined along the estuary, while napA gene numbers were stable, suggesting that NAP-mediated nitrate reduction remained important at low nitrate concentrations. nirS gene numbers (as indicators of DN) also decreased along the estuary, whereas nrfA (an indicator for DNRA) was detected only at the two uppermost sites. Similarly, nitrate and nitrite reductase gene transcripts were detected only at the top two sites. A regression analysis of log(n + 1) process rate data and log(n + 1) mean gene abundances showed significant relationships between DN and nirS and between DNRA and nrfA. Although these log-log relationships indicate an underlying relationship between the genetic potential for nitrate reduction and the corresponding process activity, fine-scale environmentally induced changes in rates of nitrate reduction are likely to be controlled at cellular and protein levels. Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Additional Information:cited By (since 1996)33
Keywords:16S rRNA gene, ANAMMOX, Aquatic environments, Bacterial removal, Dissimilatory nitrate reduction, Estuarine sediments, Functional genes, Genetic potential, In-situ, Inorganic nitrogen, Nitrate concentration, Nitrate reduction, Nitrite reductase genes, Nutrient gradients, Process activities, Protein level, Quantitative PCR, Reverse transcription, Slurry experiment, United kingdom, Ammonium compounds, Bacteriology, Denitrification, Estuaries, Genes, Nitrogen removal, Regression analysis, Transcription, Wastewater treatment, Nitrates, ammonia, nitrate, nitrate reductase, nitrite reductase, ribosome RNA, RNA 16S, ammonification, bacterium, benthic environment, concentration (composition), estuarine sediment, genetic analysis, polymerase chain reaction, protein, reduction, RNA, ammonification, article, bacterial gene, benthos, cell level, concentration (parameters), estuary, genetic transcription, genetic variability, nonhuman, nucleotide sequence, reverse transcription polymerase chain reaction, United Kingdom, Bacterial Proteins, Biodiversity, Cluster Analysis, DNA, Bacterial, DNA, Ribosomal, Geologic Sediments, Great Britain, Molecular Sequence Data, Nitrite Reductases, Nitrogen Compounds, Phylogeny, RNA, Ribosomal, 16S, Sequence Analysis, DNA, Sequence Homology, Nucleic Acid, Eurasia, Europe, United Kingdom, Western Europe, Bacteria (microorganisms)
Subjects:C Biological Sciences > C500 Microbiology
Divisions:College of Science > School of Life Sciences
ID Code:8947
Deposited On:19 Apr 2013 15:36

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