title: Microbial community functional structures in wastewater treatment plants as characterized by GeoChip.
abstract: BACKGROUND
  Biological WWTPs must be functionally stable to continuously and steadily remove contaminants which rely upon the activity of complex microbial communities. However, knowledge is still lacking in regard to microbial community functional structures and their linkages to environmental variables.
  
  
  OBJECTIVE
  To investigate microbial community functional structures of activated sludge in wastewater treatment plants (WWTPs) and to understand the effects of environmental factors on their structure.
  
  
  METHODS
  12 activated sludge samples were collected from four WWTPs in Beijing. A comprehensive functional gene array named GeoChip 4.2 was used to determine the microbial functional genes involved in a variety of biogeochemical processes such as carbon, nitrogen, phosphorous and sulfur cycles, metal resistance, antibiotic resistance and organic contaminant degradation.
  
  
  RESULTS
  High similarities of the microbial community functional structures were found among activated sludge samples from the four WWTPs, as shown by both diversity indices and the overlapped genes. For individual gene category, such as egl, amyA, lip, nirS, nirK, nosZ, ureC, ppx, ppk, aprA, dsrA, sox and benAB, there were a number of microorganisms shared by all 12 samples. Canonical correspondence analysis (CCA) showed that the microbial functional patterns were highly correlated with water temperature, dissolved oxygen (DO), ammonia concentrations and loading rate of chemical oxygen demand (COD). Based on the variance partitioning analyses (VPA), a total of 53% of microbial community variation from GeoChip data can be explained by wastewater characteristics (25%) and operational parameters (23%), respectively.
  
  
  CONCLUSIONS
  This study provided an overall picture of microbial community functional structures of activated sludge in WWTPs and discerned the linkages between microbial communities and environmental variables in WWTPs.
authors.affiliation: Environmental Simulation and Pollution Control State Key Joint Laboratory, School of Environment, Tsinghua University, Beijing, China; Department of Environmental Science and Engineering, Beijing University of Chemical Technology, Beijing, China.
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Wang
authors.affiliation: Environmental Simulation and Pollution Control State Key Joint Laboratory, School of Environment, Tsinghua University, Beijing, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Xia
authors.affiliation: Environmental Simulation and Pollution Control State Key Joint Laboratory, School of Environment, Tsinghua University, Beijing, China.
authors.forename: Xianghua
authors.initials: X
authors.lastname: Wen
authors.affiliation: Environmental Simulation and Pollution Control State Key Joint Laboratory, School of Environment, Tsinghua University, Beijing, China.
authors.forename: Yunfeng
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Environmental Simulation and Pollution Control State Key Joint Laboratory, School of Environment, Tsinghua University, Beijing, China; Institute for Environmental Genomics and Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma, United States of America; Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America.
authors.forename: Jizhong
authors.initials: J
authors.lastname: Zhou
mesh_terms: D001203:Ascomycota / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D024881:Drug Resistance, Bacterial / Q000235:genetics; D019605:Euryarchaeota / Q000235:genetics; D019766:Genes, Archaeal; D005798:Genes, Bacterial; D005800:Genes, Fungal; D064307:Microbiota / Q000235:genetics*; D058889:Molecular Typing; D020411:Oligonucleotide Array Sequence Analysis; D010088:Oxidoreductases / Q000235:genetics; D020560:Proteobacteria / Q000235:genetics; D012722:Sewage / Q000382:microbiology*; D059467:Transcriptome; D014871:Water Microbiology; D018508:Water Purification
chemical_list: D001426:Bacterial Proteins; D012722:Sewage; D010088:Oxidoreductases; C022763:nitrous oxide reductase