title: Enrichment of anodophilic nitrogen fixing bacteria in a bioelectrochemical system.
abstract: We demonstrated the ability of a bio-anode to fix dinitrogen (N2), and confirmed that diazotrophs can be used to treat N-deficient wastewater in a bioelectrochemical system (BES). A two-compartment BES was fed with an N-deficient medium containing glucose for >200 days. The average glucose and COD removal at an anodic potential of +200 mV vs. Ag/AgCl was 100% and 76%, respectively. Glucose removal occurred via fermentation under open circuit (OC), with acetate as the key byproduct. Closing circuit remarkably reduced acetate accumulation, suggesting the biofilm could oxidise acetate under N-deficient conditions. Nitrogen fixation required an anode and glucose; removing either reduced N2 fixation significantly. This suggests that diazotroph utilised glucose directly at the anode or indirectly through syntrophic interaction of an N2-fixing fermenter and an anodophile. The enriched biofilm was dominated (68%) by the genus Clostridium, members of which are known to be electrochemically active and capable of fixing N2.
authors.affiliation: CSIRO Land and Water, CSIRO, Floreat, WA 6014, Australia; School of Pathology and Laboratory Medicine, University of Western Australia, Nedlands, WA 6009, Australia.
authors.forename: Pan Yu
authors.initials: PY
authors.lastname: Wong
authors.affiliation: CSIRO Land and Water, CSIRO, Floreat, WA 6014, Australia.
authors.forename: Ka Yu
authors.initials: KY
authors.lastname: Cheng
authors.affiliation: CSIRO Land and Water, CSIRO, Floreat, WA 6014, Australia; School of Pathology and Laboratory Medicine, University of Western Australia, Nedlands, WA 6009, Australia.
authors.forename: Anna H
authors.initials: AH
authors.lastname: Kaksonen
authors.affiliation: School of Pathology and Laboratory Medicine, University of Western Australia, Nedlands, WA 6009, Australia.
authors.forename: David C
authors.initials: DC
authors.lastname: Sutton
authors.affiliation: CSIRO Land and Water, CSIRO, Floreat, WA 6014, Australia. Electronic address: maneesha.ginige@csiro.au.
authors.forename: Maneesha P
authors.initials: MP
authors.lastname: Ginige
mesh_terms: D001419:Bacteria / Q000378:metabolism*; D018441:Biofilms; D019149:Bioreactors; D003013:Clostridium / Q000302:isolation & purification; D004566:Electrodes; D005947:Glucose / Q000378:metabolism; D009584:Nitrogen / Q000737:chemistry; D009586:Nitrogen Fixation; D014865:Waste Disposal, Fluid / Q000379:methods; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000378:metabolism; D018508:Water Purification / Q000379:methods
chemical_list: D014874:Water Pollutants, Chemical; D005947:Glucose; D009584:Nitrogen
keywords: Bioelectrochemical system; Diazotroph; Microbial fuel cell; Nitrogen fixation; Nitrogen fixing bacteria