title: Insight into the overconsumption of ammonium by anammox consortia under anaerobic conditions.
abstract: OBJECTIVE
  This study gives a systematic profile of ammonium overconsumption in anammox consortia beyond the stoichiometry ratio, with aim to reveal another ammonium removal process by oxidants OH· without nitrite under anaerobic conditions.
  
  
  RESULTS
  Percoll centrifugation, flow cytometry, cloning and chemical analysis demonstrated that this ammonium removal was related to low Planctomycetes and high biomass decay. Armatimonadetes, Acidobacteria, Verrucomicrobia and Nitrosomonas initially existed in the consortia with the overconsumption of ammonium, and their levels then declined with decreasing overconsumption. The inevitable release of oxidants, such as OH, during bacterial inhibition or decay was found to be a potential source of electron acceptors capable of oxidizing ammonium.
  
  
  CONCLUSIONS
  Anaerobic ammonium removal without nitrite could occur in anammox consortia. However, it was unsteady and was not sustained over a long period. Under suitable conditions, anammox bacteria competed with others and became the dominant micro-organism responsible for the simultaneous removal of ammonium and nitrite.
  
  
  CONCLUSIONS
  This investigation will have importance to better understand the anammox process operation. The overconsumption of ammonium could be used as an indicator for fluctuations in anammox cultivation.
authors.affiliation: Department of Environmental Engineering, Peking University, Beijing, China; Key Laboratory of Water and Sediment Sciences, Ministry of Education of China, Beijing, China.
authors.forename: Z
authors.initials: Z
authors.lastname: Zhang
authors.forename: S
authors.initials: S
authors.lastname: Liu
mesh_terms: D064751:Ammonium Compounds / Q000378:metabolism*; D000693:Anaerobiosis; D001419:Bacteria / Q000302:isolation & purification / Q000378:metabolism*; D059013:Microbial Consortia; D009573:Nitrites / Q000378:metabolism; D010084:Oxidation-Reduction
chemical_list: D064751:Ammonium Compounds; D009573:Nitrites
keywords: anaerobic ammonium oxidizing; anammox; nitrogen removal; stoichiometry ratio; wastewater treatment