title: Occurrence and importance of anaerobic ammonium-oxidising bacteria in vegetable soils.
abstract: The quantitative importance of anaerobic ammonium oxidation (anammox) has been described in paddy fields, while the presence and importance of anammox in subsurface soil from vegetable fields have not been determined yet. Here, we investigated the occurrence and activity of anammox bacteria in five different types of vegetable fields located in Jiangsu Province, China. Stable isotope experiments confirmed the anammox activity in the examined soils, with the potential rates of 2.1 and 23.2 nmol N2 g(-1) dry soil day(-1), and the anammox accounted for 5.9-20.5% of total soil dinitrogen gas production. It is estimated that a total loss of 7.1-78.2 g N m(-2) year(-1) could be linked to the anammox process in the examined vegetable fields. Phylogenetic analyses showed that multiple co-occurring anammox genera were present in the examined soils, including Candidatus Brocadia, Candidatus Kuenenia, Candidatus Anammoxoglobus and Candidatus Jettenia, and Candidatus Brocadia appeared to be the most common anammox genus. Quantitative PCR further confirmed the presence of anammox bacteria in the examined soils, with the abundance varying from 2.8 × 10(5) to 3.0 × 10(6) copies g(-1) dry soil. Correlation analyses suggested that the soil ammonium concentration had significant influence on the activity and abundance of anammox bacteria in the examined soils. The results of our study showed the presence of diverse anammox bacteria and indicated that the anammox process could serve as an important nitrogen loss pathway in vegetable fields.
authors.affiliation: Jiangsu Key Laboratory of Agricultural Meteorology, Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, College of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing, 210044, China.
authors.forename: Li-dong
authors.initials: LD
authors.lastname: Shen
authors.forename: Hong-sheng
authors.initials: HS
authors.lastname: Wu
authors.forename: Zhi-qiu
authors.initials: ZQ
authors.lastname: Gao
authors.forename: Xiang-hua
authors.initials: XH
authors.lastname: Xu
authors.forename: Tie-xi
authors.initials: TX
authors.lastname: Chen
authors.forename: Shuai
authors.initials: S
authors.lastname: Liu
authors.forename: Hai-xiang
authors.initials: HX
authors.lastname: Cheng
mesh_terms: D064751:Ammonium Compounds / Q000378:metabolism*; D000693:Anaerobiosis; D001421:Bacteria, Anaerobic / Q000145:classification / Q000254:growth & development* / Q000378:metabolism*; D002681:China; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D007553:Isotope Labeling; D008969:Molecular Sequence Data; D009584:Nitrogen / Q000378:metabolism; D010084:Oxidation-Reduction; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology; D014675:Vegetables / Q000254:growth & development*
chemical_list: D064751:Ammonium Compounds; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D009584:Nitrogen