title: Comparison of the microbial population dynamics and phylogenetic characterization of a CANOXIS reactor and a UASB reactor degrading trichloroethene.
abstract: OBJECTIVE
  To understand the microbial ecology underlying trichloethene (TCE) degradation in a coupled anaerobic/aerobic single stage (CANOXIS) reactor oxygenated with hydrogen peroxide (H2O2) and in an upflow anaerobic sludge bed (UASB) reactor.
  
  
  RESULTS
  The molecular study of the microbial population dynamics and a phylogenetic characterization were conducted using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). In both reactors, TCE had a toxic effect on two uncultured bacterial populations whereas oxygen favoured the growth of aerobic species belonging to Rhizobiaceae and Dechloromonas. No methanotrophic bacteria were detected when targeting 16S rRNA gene with universal primers. Alternatively, pmo gene encoding the particulate methane monooxygenase of Methylomonas sp. LW21 could be detected in the coupled reactor when H2O2 was supplied at 0.7 g O2 l day(-1).
  
  
  CONCLUSIONS
  Methylomonas sp. LW21 that could be responsible for the aerobic degradation of the TCE by-products is not among the predominant bacterial populations in the coupled reactor. It seems to have been outcompeted by heterotrophic bacteria (Rhizobiaceae and Dechloromonas sp.) for oxygen.
  
  
  CONCLUSIONS
  The results obtained show the limitations of the coupled reactor examined in this study. Further investigations should focus on the operating conditions of this reactor in order to favour the growth of the methanotrophs.
authors.affiliation: Biotechnology Research Institute, National Research Council Canada, Montréal, Québec, Canada. odile.tresse@lille.inra.fr
authors.forename: O
authors.initials: O
authors.lastname: Tresse
authors.forename: F
authors.initials: F
authors.lastname: Mounien
authors.forename: M-J
authors.initials: MJ
authors.lastname: Lévesque
authors.forename: S
authors.initials: S
authors.lastname: Guiot
mesh_terms: D001420:Bacteria, Aerobic; D001421:Bacteria, Anaerobic; D001673:Biodegradation, Environmental; D019149:Bioreactors; D011157:Population Dynamics; D012989:Soil Pollutants; D014241:Trichloroethylene
chemical_list: D012989:Soil Pollutants; D014241:Trichloroethylene