title: [Study on nitrate-nitrogen removal and community analysis of denitrifying bacteria in downflow fixed-bed bioreactor].
abstract: OBJECTIVE
  To study the community of denitrifying bacteria and nitrate-nitrogen removal in downflow fixed-bed bioreactor.
  
  
  METHODS
  Porous ceramics were used as immobilization carrier. Optimum conditions for nitrate-nitrogen removal of downflow fixed-bed bioreactor were studied. Morphology of immobilized denitrifying bacteria was observed by scanning electron microscope and their community analysis were processed by 16S rDNA sequencing.
  
  
  RESULTS
  The optimum conditions for denitrification were T = 35 degrees C and pH8.0. NO3- -N was consumed 99% within the 10h while removal efficiency reached 91% and followed the zero-order kinetics in the first 4h. Majorities of denitrifying bacteria were bacillus. 16SrDNA homology analysis showed that denitrifying bacteria included P. putida, P. nitroreducens, S. maltophilia, C. testosteroni and Ochrobactrum sp etc.
  
  
  CONCLUSIONS
  There were high nitrate-nitrogen removal efficiency and diversity of denitrifying bacteria in downflow fixed-bed bioreactor.
authors.affiliation: MOE Key Lab of Environment and Health, Institute of Environmental Medicine, Tongji Medical College, Huazhong University of Science & Technology, Wuhan 430030, China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Huang
authors.forename: Xiaochun
authors.initials: X
authors.lastname: Chen
authors.forename: Hongyan
authors.initials: H
authors.lastname: Liu
authors.forename: Weiwei
authors.initials: W
authors.lastname: Zhang
mesh_terms: D001419:Bacteria / Q000145:classification / Q000378:metabolism*; D019149:Bioreactors / Q000382:microbiology*; D009566:Nitrates / Q000302:isolation & purification* / Q000378:metabolism; D009584:Nitrogen / Q000302:isolation & purification* / Q000378:metabolism; D014865:Waste Disposal, Fluid / Q000379:methods
chemical_list: D009566:Nitrates; D009584:Nitrogen