title: Distribution patterns of nitrogen micro-cycle functional genes and their quantitative coupling relationships with nitrogen transformation rates in a biotrickling filter.
abstract: The present study explored the distribution patterns of nitrogen micro-cycle genes and the underlying mechanisms responsible for nitrogen transformation at the molecular level (genes) in a biotrickling filter (biofilter). The biofilter achieved high removal efficiencies for ammonium (NH4(+)-N) (80-94%), whereas nitrate accumulated at different levels under a progressive NH4(+)-N load. Combined analyses revealed the anammox, nas, napA, narG, nirS, and nxrA genes were the dominant enriched genes in different treatment layers. The presence of simultaneous nitrification, ammonium oxidation (anammox), and dissimilatory nitrate reduction to ammonium (DNRA) were the primary factors accounted for the robust NH4(+)-N treatment performance. The presence of DNRA, nitrification, and denitrification was determined to be a pivotal pathway that contributed to the nitrate accumulation in the biofilter. The enrichment of functional genes at different depth gradients and the multi-path coupled cooperation at the functional gene level are conducive to achieving complete nitrogen removal.
authors.affiliation: Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100, Shaanxi, China; Key Laboratory of Water and Sediment Sciences, Ministry of Education, Department of Environmental Engineering, Peking University, Beijing 100871, China.
authors.forename: Honglei
authors.initials: H
authors.lastname: Wang
authors.affiliation: Key Laboratory of Water and Sediment Sciences, Ministry of Education, Department of Environmental Engineering, Peking University, Beijing 100871, China. Electronic address: jiguodong@pku.edu.cn.
authors.forename: Guodong
authors.initials: G
authors.lastname: Ji
authors.affiliation: State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun 130117, China.
authors.forename: Xueyuan
authors.initials: X
authors.lastname: Bai
mesh_terms: D064751:Ammonium Compounds / Q000378:metabolism; D058440:Denitrification / Q000235:genetics; D005374:Filtration / Q000295:instrumentation* / Q000379:methods; D015964:Gene Expression Regulation, Bacterial; D050901:Nitrate Reductase / Q000235:genetics; D009566:Nitrates / Q000378:metabolism; D058465:Nitrification / Q000235:genetics; D009584:Nitrogen / Q000378:metabolism*; D010084:Oxidation-Reduction; D018508:Water Purification / Q000295:instrumentation* / Q000379:methods
chemical_list: D064751:Ammonium Compounds; D009566:Nitrates; D050901:Nitrate Reductase; D009584:Nitrogen
keywords: Biofilter; DNRA; Distribution pattern; Nitrification; Quantitative relationship