title: [Structure of planktonic ammonia-oxidizing community in the waters near the Three Gorges Dam of the Yangtze River].
abstract: OBJECTIVE
  Investigation of ammonia-oxidizing microorganisms (AOM) in natural environments is of great importance to understand global nitrogen cycling. However, little is known about the effects of dam constructions on the AOM community. We studied the diversity of the free-living and particle-attached AOM populations in the waters behind and in front of the Three Gorges Dam of the Yangtze River, and analyzed the possible correlation between the observed difference in the two fractions of AOM with the environmental parameters.
  
  
  METHODS
  Two sampling locations near the Three Gorges Dam were selected: one behind and the other in front of the dam. Physicochemical profiles of waters at each location were measured, and the biomass in the waters was collected by filtration. The diversity of AOM in the collected samples was investigated by using an integrated approach including reverse transcription and clone library construction.
  
  
  RESULTS
  The turbidity, dissolved oxygen, and redox potential of the water in front of the dam were higher than those behind the dam. The AOM population behind and in front of the dam was dominated by ammonia-oxidizing archaea, whereas the ammonia-oxidizing bacteria were not detected. The distribution of free-living and particle-attached AOA behind and in front of the dam was different: the particle-attached AOA behind the dam was more diverse than that in front of the dam, whereas the free-living AOA showed the opposite tendency; the difference between the fractions of AOA behind the dam was apparently higher than that in front of the dam.
  
  
  CONCLUSIONS
  The dominant AOA population did not show significant variation in the waters behind and in front of the dam, whereas the altered water dynamics resulted from the TGD construction may change the distribution of free-living and particle-attached AOA fractions in the waters behind and in front of the dam.
authors.affiliation: State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Geomicrobiology Laboratory, Beijing 100083, China. huanglq1987@163.com
authors.forename: Liuqin
authors.initials: L
authors.lastname: Huang
authors.forename: Hongchen
authors.initials: H
authors.lastname: Jiang
authors.forename: Shang
authors.initials: S
authors.lastname: Wang
authors.forename: Chuanlun
authors.initials: C
authors.lastname: Zhang
authors.forename: Hailiang
authors.initials: H
authors.lastname: Dong
mesh_terms: D000641:Ammonia / Q000378:metabolism*; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002681:China; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D010802:Phylogeny; D010933:Plankton / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D045483:Rivers / Q000382:microbiology*
chemical_list: D001426:Bacterial Proteins; D000641:Ammonia; D010088:Oxidoreductases; C045582:ammonia monooxygenase