title: Effect of electrochemical redox reaction on biochemical ammonium oxidation and chemical nitrite oxidation.
abstract: A modified graphite felt electrode with neutral red (NRelectrode) was shown to catalyze the chemical oxidation of nitrite to nitrate under aerobic conditions. The electrochemically oxidized NR-electrode (EO-NR-electrode) and reduced NR-electrode (ER-NR-electrode) catalyzed the oxidation of 1,094+/-39 mg/l and 382+/-45 mg/l of nitrite, respectively, for 24 h. The electrically uncharged NRelectrode (EU-NR-electrode) catalyzed the oxidation of 345+/-47 mg/l of nitrite for 24 h. The aerobic bacterial community immobilized in the EO-NR-electrode did not oxidize ammonium to nitrite; however, the aerobic bacterial community immobilized in the ER-NR-electrode bioelectrochemically oxidized 1,412+/-39 mg/l of ammonium for 48 h. Meanwhile, the aerobic bacterial community immobilized on the EU-NR-electrode biochemically oxidized 449+/-22 mg/l of ammonium for 48 h. In the continuous culture system, the aerobic bacterial community immobilized on the ER-NR-electrode bioelectrochemically oxidized a minimal 1,337+/-38 mg/l to a maximal 1,480+/-38 mg/l of ammonium to nitrate, and the community immobilized on the EU-NR-electrode biochemically oxidized a minimal 327+/-23 mg/l to a maximal 412+/-26 mg/l of ammonium to nitrate every two days. The bacterial communities cultivated in the ER-NR-electrode and EU-NR-electrode in the continuous culture system were analyzed by TGGE on the 20th and 50th days of incubation. Some ammoniumoxidizing bacteria were enriched on the ER-NR-electrode, but not on the EU-NR-electrode.
authors.affiliation: Department of Biological Engineering, Seokyeong University, Seoul 136-704, Korea.
authors.forename: Bo Young
authors.initials: BY
authors.lastname: Jeon
authors.forename: Ha Na
authors.initials: HN
authors.lastname: Seo
authors.forename: Seung Won
authors.initials: SW
authors.lastname: Kang
authors.forename: Doo Hyun
authors.initials: DH
authors.lastname: Park
mesh_terms: D001419:Bacteria / Q000235:genetics / Q000378:metabolism*; D019149:Bioreactors / Q000382:microbiology*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004563:Electrochemistry / Q000379:methods; D004566:Electrodes; D004591:Electrophoresis, Polyacrylamide Gel; D006108:Graphite / Q000737:chemistry; D009573:Nitrites / Q000737:chemistry* / Q000378:metabolism; D010084:Oxidation-Reduction; D016133:Polymerase Chain Reaction; D000644:Quaternary Ammonium Compounds / Q000737:chemistry* / Q000378:metabolism; D012336:RNA, Ribosomal, 16S / Q000737:chemistry / Q000235:genetics; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D009573:Nitrites; D000644:Quaternary Ammonium Compounds; D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical; D006108:Graphite