title: Identification of the autotrophic denitrifying community in nitrate removal reactors by DNA-stable isotope probing.
abstract: Autotrophic denitrification has attracted increasing attention for wastewater with insufficient organic carbon sources. Nevertheless, in situ identification of autotrophic denitrifying communities in reactors remains challenging. Here, a process combining micro-electrolysis and autotrophic denitrification with high nitrate removal efficiency was presented. Two batch reactors were fed organic-free nitrate influent, with H13CO3-and H12CO3-as inorganic carbon sources. DNA-based stable-isotope probing (DNA-SIP) was used to obtain molecular evidence for autotrophic denitrifying communities. The results showed that the nirS gene was strongly labeled by H13CO3-, demonstrating that the inorganic carbon source was assimilated by autotrophic denitrifiers. High-throughput sequencing and clone library analysis identified Thiobacillus-like bacteria as the most dominant autotrophic denitrifiers. However, 88% of nirS genes cloned from the13C-labeled "heavy" DNA fraction showed low similarity with all culturable denitrifiers. These findings provided functional and taxonomical identification of autotrophic denitrifying communities, facilitating application of autotrophic denitrification process for wastewater treatment.
authors.affiliation: School of Civil Engineering, Beijing Jiaotong University, Beijing 100044, China; Beijing Key Laboratory of Aqueous Typical Pollutants Control and Water Quality Safeguard, Beijing 100044, China. Electronic address: weix@bjtu.edu.cn.
authors.forename: Wei
authors.initials: W
authors.lastname: Xing
authors.affiliation: School of Civil Engineering, Beijing Jiaotong University, Beijing 100044, China.
authors.forename: Jinlong
authors.initials: J
authors.lastname: Li
authors.affiliation: School of Civil Engineering, Beijing Jiaotong University, Beijing 100044, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Cong
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Gao
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China.
authors.forename: Zhongjun
authors.initials: Z
authors.lastname: Jia
authors.affiliation: School of Civil Engineering, Beijing Jiaotong University, Beijing 100044, China; Beijing Key Laboratory of Aqueous Typical Pollutants Control and Water Quality Safeguard, Beijing 100044, China. Electronic address: dsli@bjtu.edu.cn.
authors.forename: Desheng
authors.initials: D
authors.lastname: Li
mesh_terms: D052818:Autotrophic Processes; D019149:Bioreactors / Q000382:microbiology*; D002244:Carbon / Q000378:metabolism; D002247:Carbon Isotopes; D004247:DNA; D015342:DNA Probes; D058440:Denitrification; D004572:Electrolysis / Q000379:methods; D059014:High-Throughput Nucleotide Sequencing; D059013:Microbial Consortia / Q000235:genetics / Q000502:physiology; D009566:Nitrates / Q000378:metabolism*; D013855:Thiobacillus / Q000235:genetics* / Q000378:metabolism; D014865:Waste Disposal, Fluid / Q000295:instrumentation / Q000379:methods*; D062065:Wastewater / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000378:metabolism
chemical_list: D002244:Carbon; D002247:Carbon Isotopes; D004247:DNA; D015342:DNA Probes; D009566:Nitrates; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Autotrophic denitrification; Microbial community; Nitrate removal; Stable-isotope probing; Thiobacillus