title: Characterization of microbial communities removing nitrogen oxides from flue gas: the BioDeNOx process.
abstract: BioDeNOx is an integrated physicochemical and biological process for the removal of nitrogen oxides (NOx) from flue gases. In this process, the flue gas is purged through a scrubber containing a solution of Fe(II)EDTA2-, which binds the NOx to form an Fe(II)EDTA.NO2- complex. Subsequently, this complex is reduced in the bioreactor to dinitrogen by microbial denitrification. Fe(II)EDTA2-, which is oxidized to Fe(III)EDTA- by oxygen in the flue gas, is regenerated by microbial iron reduction. In this study, the microbial communities of both lab- and pilot-scale reactors were studied using culture-dependent and -independent approaches. A pure bacterial strain, KT-1, closely affiliated by 16S rRNA analysis to the gram-positive denitrifying bacterium Bacillus azotoformans, was obtained. DNA-DNA homology of the isolate with the type strain was 89%, indicating that strain KT-1 belongs to the species B. azotoformans. Strain KT-1 reduces Fe(II)EDTA.NO2- complex to N2 using ethanol, acetate, and Fe(II)EDTA2- as electron donors. It does not reduce Fe(III)EDTA-. Denaturing gradient gel electrophoresis analysis of PCR-amplified 16S rRNA gene fragments showed the presence of bacteria closely affiliated with members of the phylum Deferribacteres, an Fe(III)-reducing group of bacteria. Fluorescent in situ hybridization with oligonucleotide probes designed for strain KT-1 and members of the phylum Deferribacteres showed that the latter were more dominant in both reactors.
authors.affiliation: Dept. of Biotechnology, Julianalaan 67, NL-2628 BC Delft, The Netherlands.
authors.forename: Rajkumari
authors.initials: R
authors.lastname: Kumaraswamy
authors.forename: Udo
authors.initials: U
authors.lastname: van Dongen
authors.forename: J Gijs
authors.initials: JG
authors.lastname: Kuenen
authors.forename: Wiebe
authors.initials: W
authors.lastname: Abma
authors.forename: Mark C M
authors.initials: MC
authors.lastname: van Loosdrecht
authors.forename: Gerard
authors.initials: G
authors.lastname: Muyzer
mesh_terms: D001407:Bacillus / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D001419:Bacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D019149:Bioreactors / Q000382:microbiology*; D003470:Culture Media; D004269:DNA, Bacterial / Q000032:analysis; D017753:Ecosystem; D004492:Edetic Acid / Q000378:metabolism; D005290:Ferric Compounds / Q000378:metabolism; D005296:Ferrous Compounds / Q000378:metabolism; D005740:Gases / Q000737:chemistry*; D017404:In Situ Hybridization, Fluorescence; D008969:Molecular Sequence Data; D009589:Nitrogen Oxides / Q000378:metabolism*; D009693:Nucleic Acid Hybridization; D010084:Oxidation-Reduction; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics
chemical_list: D003470:Culture Media; D004269:DNA, Bacterial; D005290:Ferric Compounds; D005296:Ferrous Compounds; D005740:Gases; D009589:Nitrogen Oxides; D012336:RNA, Ribosomal, 16S; C055526:Fe(II)-EDTA; D004492:Edetic Acid; C019179:Fe(III)-EDTA