title: Tracking the dynamics of heterotrophs and nitrifiers in moving-bed biofilm reactors operated at different COD/N ratios.
abstract: In this study, the impact of COD/N ratio and feeding regime on the dynamics of heterotrophs and nitrifiers in moving-bed biofilm reactors was addressed. Based on DGGE analysis of 16S rRNA genes, the influent COD was found to be the main factor determining the overall bacterial diversity. The amoA-gene-based analysis suggested that the dynamic behavior of the substrate in continuous and pulse-feeding reactors influenced the selection of specific ammonium-oxidizing bacteria (AOB) strains. Furthermore, AOB diversity was directly related to the applied COD/N ratio and ammonium-nitrogen load. Maximum specific ammonium oxidation rates observed under non-substrate-limiting conditions were observed to be proportional to the fraction of nitrifiers within the bacterial community. FISH analysis revealed that Nitrosomonas genus dominated the AOB community in all reactors. Moreover, Nitrospira was found to be the only nitrite-oxidizing bacteria (NOB) in the fully autotrophic system, whereas Nitrobacter represented the dominant NOB genus in the organic carbon-fed reactors.
authors.affiliation: Department of Biotechnology, Delft University of Technology, Delft, The Netherlands; Chemical Engineering Program, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil. Electronic address: jbassin@peq.coppe.ufrj.br.
authors.forename: J P
authors.initials: JP
authors.lastname: Bassin
authors.affiliation: Department of Biotechnology, Delft University of Technology, Delft, The Netherlands.
authors.forename: B
authors.initials: B
authors.lastname: Abbas
authors.affiliation: Institute of Microbiology Prof. Paulo de Goés, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: C L S
authors.initials: CL
authors.lastname: Vilela
authors.affiliation: Department of Biotechnology, Delft University of Technology, Delft, The Netherlands.
authors.forename: R
authors.initials: R
authors.lastname: Kleerebezem
authors.affiliation: Department of Biotechnology, Delft University of Technology, Delft, The Netherlands.
authors.forename: G
authors.initials: G
authors.lastname: Muyzer
authors.affiliation: Institute of Microbiology Prof. Paulo de Goés, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: A S
authors.initials: AS
authors.lastname: Rosado
authors.affiliation: Department of Biotechnology, Delft University of Technology, Delft, The Netherlands.
authors.forename: M C M
authors.initials: MC
authors.lastname: van Loosdrecht
authors.affiliation: Chemical Engineering Program, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: M
authors.initials: M
authors.lastname: Dezotti
mesh_terms: D064751:Ammonium Compounds / Q000378:metabolism; D018441:Biofilms; D019149:Bioreactors / Q000382:microbiology*; D058465:Nitrification / Q000235:genetics; D009573:Nitrites / Q000378:metabolism; D009576:Nitrobacter / Q000235:genetics / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism*; D009606:Nitrosomonas / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000235:genetics
chemical_list: D064751:Ammonium Compounds; D009573:Nitrites; D012336:RNA, Ribosomal, 16S; D009584:Nitrogen; D010100:Oxygen
keywords: DGGE; FISH; MBBR; Microbial diversity; Nitrification