title: Community composition and activity of anaerobic ammonium oxidation bacteria in the rhizosphere of salt-marsh grass Spartina alterniflora.
abstract: Anaerobic ammonium oxidation (anammox) as an important nitrogen removal pathway has been investigated in intertidal marshes. However, the rhizosphere-driven anammox process in these ecosystems is largely overlooked so far. In this study, the community dynamics and activities of anammox bacteria in the rhizosphere and non-rhizosphere sediments of salt-marsh grass Spartina alterniflora (a widely distributed plant in estuaries and intertidal ecosystems) were investigated using clone library analysis, quantitative PCR assay, and isotope-tracing technique. Phylogenetic analysis showed that anammox bacterial diversity was higher in the non-rhizosphere sediments (Scalindua and Kuenenia) compared with the rhizosphere zone (only Scalindua genus). Higher abundance of anammox bacteria was detected in the rhizosphere (6.46 × 10(6)-1.56 × 10(7) copies g(-1)), which was about 1.5-fold higher in comparison with that in the non-rhizosphere zone (4.22 × 10(6)-1.12 × 10(7) copies g(-1)). Nitrogen isotope-tracing experiments indicated that the anammox process in the rhizosphere contributed to 12-14 % N2 generation with rates of 0.43-1.58 nmol N g(-1) h(-1), while anammox activity in the non-rhizosphere zone contributed to only 4-7 % N2 production with significantly lower activities (0.28-0.83 nmol N g(-1) h(-1)). Overall, we propose that the rhizosphere microenvironment in intertidal marshes might provide a favorable niche for anammox bacteria and thus plays an important role in nitrogen cycling.
authors.affiliation: College of Geographical Sciences, East China Normal University, Shanghai, 200241, China.|State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, 200062, China.
authors.forename: Yanling
authors.initials: Y
authors.lastname: Zheng
authors.affiliation: State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, 200062, China. ljhou@sklec.ecnu.edu.cn.
authors.forename: Lijun
authors.initials: L
authors.lastname: Hou
authors.affiliation: College of Geographical Sciences, East China Normal University, Shanghai, 200241, China. mliu@geo.ecnu.edu.cn.
authors.forename: Min
authors.initials: M
authors.lastname: Liu
authors.affiliation: College of Geographical Sciences, East China Normal University, Shanghai, 200241, China.|State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, 200062, China.
authors.forename: Guoyu
authors.initials: G
authors.lastname: Yin
authors.affiliation: State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, 200062, China.
authors.forename: Juan
authors.initials: J
authors.lastname: Gao
authors.affiliation: State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, 200062, China.
authors.forename: Xiaofen
authors.initials: X
authors.lastname: Jiang
authors.affiliation: College of Geographical Sciences, East China Normal University, Shanghai, 200241, China.
authors.forename: Xianbiao
authors.initials: X
authors.lastname: Lin
authors.affiliation: College of Geographical Sciences, East China Normal University, Shanghai, 200241, China.
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Li
authors.affiliation: State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, 200062, China.
authors.forename: Chendi
authors.initials: C
authors.lastname: Yu
authors.affiliation: State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, 200062, China.
authors.forename: Rong
authors.initials: R
authors.lastname: Wang
mesh_terms: D064751:Ammonium Compounds / Q000378:metabolism*; D001419:Bacteria / Q000145:classification* / Q000378:metabolism*; D058448:Biota; D007553:Isotope Labeling; D009584:Nitrogen / Q000378:metabolism; D010084:Oxidation-Reduction; D010802:Phylogeny; D006109:Poaceae / Q000254:growth & development*; D016133:Polymerase Chain Reaction; D058441:Rhizosphere; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology
chemical_list: D064751:Ammonium Compounds; D009584:Nitrogen
keywords: Anaerobic ammonium oxidation (anammox); Intertidal sediment; Nitrogen cycle; Rhizosphere; Spartina alterniflora