title: Coexistence of nitrifiers, denitrifiers and Anammox bacteria in a sequencing batch biofilm reactor as revealed by PCR-DGGE.
abstract: OBJECTIVE
  The bacterial diversity in a sequencing batch biofilm reactor (SBBR) treating landfill leachate was studied to explain the mechanism of nitrogen removal.
  
  
  RESULTS
  The total microbial DNA was extracted from samples collected from landfill leachate and biofilm of the reactor with the removal efficiencies of NH(4) (+)-N higher than 97% and that of chemical oxygen demand (determined by K(2)Cr(2)O(7), COD(Cr)) higher than 86%. Denaturing gradient gel electrophoresis (DGGE) fingerprints based on total community 16S rRNA genes were analyzed with statistical methods, and excised DNA bands were sequenced. The results of phylogenetic analyses revealed high diversity within the SBBR biofilm community, and DGGE banding patterns showed that the community structure in the biofilm remained stable during the running period.
  
  
  CONCLUSIONS
  A coexistence of nitrifiers, including ammonia-oxidizing bacteria and nitrite-oxidizing bacteria, denitrifiers, including aerobic or anaerobic denitrifying bacteria and Anammox bacteria were detected, which might be the real matter of high removal efficiencies of NH(4) (+)-N and COD(Cr) in the reactor.
  
  
  CONCLUSIONS
  The findings in this study indicated that PCR-DGGE analysis could be used for microbial community detection as prior method, and the SBBR technique could provide preferable growing environment for bacteria with N removal function.
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Xiao
authors.forename: G M
authors.initials: GM
authors.lastname: Zeng
authors.forename: Z H
authors.initials: ZH
authors.lastname: Yang
authors.forename: Y Sh
authors.initials: YSh
authors.lastname: Liu
authors.forename: Y H
authors.initials: YH
authors.lastname: Ma
authors.forename: L
authors.initials: L
authors.lastname: Yang
authors.forename: R J
authors.initials: RJ
authors.lastname: Wang
authors.forename: Zh Y
authors.initials: ZhY
authors.lastname: Xu
mesh_terms: D000641:Ammonia / Q000378:metabolism; D001420:Bacteria, Aerobic / Q000235:genetics / Q000302:isolation & purification*; D001421:Bacteria, Anaerobic / Q000235:genetics / Q000302:isolation & purification*; D001673:Biodegradation, Environmental; D018441:Biofilms; D019149:Bioreactors / Q000382:microbiology*; D004269:DNA, Bacterial / Q000235:genetics; D004587:Electrophoresis, Agar Gel; D009573:Nitrites / Q000378:metabolism; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000379:methods; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D009573:Nitrites; D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical; D000641:Ammonia