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| Titel |
Diversity and distribution of amoA-type nitrifying and nirS-type denitrifying microbial communities in the Yangtze River estuary |
| VerfasserIn |
Y. Zhang, X. Xie, N. Jiao, S. S.-Y. Hsiao, S.-J. Kao |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 11, no. 8 ; Nr. 11, no. 8 (2014-04-16), S.2131-2145 |
| Datensatznummer |
250117365
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| Publikation (Nr.) |
 copernicus.org/bg-11-2131-2014.pdf |
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| Zusammenfassung |
| Coupled nitrification–denitrification plays a critical role in the removal
of excess nitrogen, which is chiefly caused by humans, to mitigate estuary
and coastal eutrophication. Despite its obvious importance, limited
information about the relationships between nitrifying and denitrifying
microbial communities in estuaries, and their controlling factors have been
documented. We investigated the nitrifying and denitrifying microbial
communities in the estuary of turbid subtropical Yangtze River (YRE), the
largest river in Asia, by analyzing the ammonia monooxygenase gene
amoA, including archaeal and bacterial amoA, and the
dissimilatory nitrite reductase gene nirS using clone libraries and
quantitative PCR (qPCR). The diversity indices and rarefaction analysis
revealed a quite low diversity for both β-proteobacterial and archaeal
amoA genes, but qPCR data showed significantly higher amoA
gene copy numbers for archaea than β-proteobacteria. Compared with the
amoA gene, a significantly higher level of diversity but lower gene
copy numbers were found for the nirS gene. Nitrification and
denitrification rates based on 15N incubation experiments supported gene
abundance data as denitrification rates were below detection limit,
suggesting lower denitrification than nitrification potential. In general,
the abundances of the amoA and nirS genes were
significantly higher in the bottom samples than the surface ones, and in the
high-turbidity river mouth, were significantly higher in the
particle-associated (> 3 μm) than the free-living
(0.2 ~ 3 μm) communities. Notably, positive correlations
between the amoA and nirS gene abundances suggested
potential gene-based coupling between nitrification and denitrification,
especially for the particle-associated assemblages. Statistical analysis of
correlations between the community structure, gene abundances and
environmental variables further revealed that dissolved oxygen and total
suspended material might be the key factors controlling community spatial
structure and regulating nitrification and denitrification potentials in the
YRE ecosystem. |
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