title: Fe(III) reduction and U(VI) immobilization by Paenibacillus sp. strain 300A, isolated from Hanford 300A subsurface sediments.
abstract: A facultative iron-reducing [Fe(III)-reducing] Paenibacillus sp. strain was isolated from Hanford 300A subsurface sediment biofilms that was capable of reducing soluble Fe(III) complexes [Fe(III)-nitrilotriacetic acid and Fe(III)-citrate] but unable to reduce poorly crystalline ferrihydrite (Fh). However, Paenibacillus sp. 300A was capable of reducing Fh in the presence of low concentrations (2 μM) of either of the electron transfer mediators (ETMs) flavin mononucleotide (FMN) or anthraquinone-2,6-disulfonate (AQDS). Maximum initial Fh reduction rates were observed at catalytic concentrations (<10 μM) of either FMN or AQDS. Higher FMN concentrations inhibited Fh reduction, while increased AQDS concentrations did not. We also found that Paenibacillus sp. 300A could reduce Fh in the presence of natural ETMs from Hanford 300A subsurface sediments. In the absence of ETMs, Paenibacillus sp. 300A was capable of immobilizing U(VI) through both reduction and adsorption. The relative contributions of adsorption and microbial reduction to U(VI) removal from the aqueous phase were ∼7:3 in PIPES [piperazine-N,N'-bis(2-ethanesulfonic acid)] and ∼1:4 in bicarbonate buffer. Our study demonstrated that Paenibacillus sp. 300A catalyzes Fe(III) reduction and U(VI) immobilization and that these reactions benefit from externally added or naturally existing ETMs in 300A subsurface sediments.
authors.affiliation: The Gene and Linda Voiland School of Chemical Engineering, Washington State University, Pullman, Washington, USA.
authors.forename: Bulbul
authors.initials: B
authors.lastname: Ahmed
authors.forename: Bin
authors.initials: B
authors.lastname: Cao
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: McLean
authors.forename: Tuba
authors.initials: T
authors.lastname: Ica
authors.forename: Alice
authors.initials: A
authors.lastname: Dohnalkova
authors.forename: Ozlem
authors.initials: O
authors.lastname: Istanbullu
authors.forename: Akin
authors.initials: A
authors.lastname: Paksoy
authors.forename: Jim K
authors.initials: JK
authors.lastname: Fredrickson
authors.forename: Haluk
authors.initials: H
authors.lastname: Beyenal
mesh_terms: D000880:Anthraquinones / Q000378:metabolism; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D005290:Ferric Compounds / Q000378:metabolism*; D005486:Flavin Mononucleotide / Q000378:metabolism; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D056507:Paenibacillus / Q000302:isolation & purification / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology; D017974:Uranium Compounds / Q000378:metabolism*
chemical_list: D000880:Anthraquinones; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D005290:Ferric Compounds; D012336:RNA, Ribosomal, 16S; D017974:Uranium Compounds; C408124:anthraquinone-2,6-disulfonate; D005486:Flavin Mononucleotide