title: Orenia metallireducens sp. nov. Strain Z6, a Novel Metal-Reducing Member of the Phylum Firmicutes from the Deep Subsurface.
abstract: A novel halophilic and metal-reducing bacterium, Orenia metallireducens strain Z6, was isolated from briny groundwater extracted from a 2.02 km-deep borehole in the Illinois Basin, IL. This organism shared 96% 16S rRNA gene similarity with Orenia marismortui but demonstrated physiological properties previously unknown for this genus. In addition to exhibiting a fermentative metabolism typical of the genus Orenia, strain Z6 reduces various metal oxides [Fe(III), Mn(IV), Co(III), and Cr(VI)], using H2as the electron donor. Strain Z6 actively reduced ferrihydrite over broad ranges of pH (6 to 9.6), salinity (0.4 to 3.5 M NaCl), and temperature (20 to 60°C). At pH 6.5, strain Z6 also reduced more crystalline iron oxides, such as lepidocrocite (γ-FeOOH), goethite (α-FeOOH), and hematite (α-Fe2O3). Analysis of X-ray absorption fine structure (XAFS) following Fe(III) reduction by strain Z6 revealed spectra from ferrous secondary mineral phases consistent with the precipitation of vivianite [Fe3(PO4)2] and siderite (FeCO3). The draft genome assembled for strain Z6 is 3.47 Mb in size and contains 3,269 protein-coding genes. Unlike the well-understood iron-reducing Shewanella and Geobacter species, this organism lacks the c-type cytochromes for typical Fe(III) reduction. Strain Z6 represents the first bacterial species in the genus Orenia (order Halanaerobiales) reported to reduce ferric iron minerals and other metal oxides. This microbe expands both the phylogenetic and physiological scopes of iron-reducing microorganisms known to inhabit the deep subsurface and suggests new mechanisms for microbial iron reduction. These distinctions from other Orenia spp. support the designation of strain Z6 as a new species, Orenia metallireducens sp. nov.
  
  
  
  A novel iron-reducing species, Orenia metallireducens sp. nov., strain Z6, was isolated from groundwater collected from a geological formation located 2.02 km below land surface in the Illinois Basin, USA. Phylogenetic, physiologic, and genomic analyses of strain Z6 found it to have unique properties for iron reducers, including (i) active microbial iron-reducing capacity under broad ranges of temperatures (20 to 60°C), pHs (6 to 9.6), and salinities (0.4 to 3.5 M NaCl), (ii) lack of c-type cytochromes typically affiliated with iron reduction in Geobacter and Shewanella species, and (iii) being the only member of the Halanaerobiales capable of reducing crystalline goethite and hematite. This study expands the scope of phylogenetic affiliations, metabolic capacities, and catalytic mechanisms for iron-reducing microbes.
authors: Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois, USA Department of Geology, University of Illinois, Urbana-Champaign, Champaign, Illinois, USA Energy Biosciences Institute, University of Illinois, Urbana-Champaign, Urbana, Illinois, USA dong5600@illinois.edu.
authors: Yiran
authors: Y
authors: Dong
authors: Department of Geology, University of Illinois, Urbana-Champaign, Champaign, Illinois, USA.
authors: Robert A
authors: RA
authors: Sanford
authors: Biosciences Division, Argonne National Laboratory, Lemont, Illinois, USA Institute of Chemical Engineering, Bulgarian Academy of Sciences, Sofia, Bulgaria.
authors: Maxim I
authors: MI
authors: Boyanov
authors: Biosciences Division, Argonne National Laboratory, Lemont, Illinois, USA.
authors: Kenneth M
authors: KM
authors: Kemner
authors: Biosciences Division, Argonne National Laboratory, Lemont, Illinois, USA.
authors: Theodore M
authors: 0000-0002-1838-8942
authors: TM
authors: Flynn
authors: Biosciences Division, Argonne National Laboratory, Lemont, Illinois, USA.
authors: Edward J
authors: EJ
authors: O'Loughlin
authors: Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois, USA High Performance and Research Computing, Office of Information Technology, Rutgers University, New Brunswick, New Jersey, USA.
authors: Yun-Juan
authors: YJ
authors: Chang
authors: Illinois State Geology Survey, University of Illinois, Urbana-Champaign, Champaign, Illinois, USA.
authors: Randall A
authors: RA
authors: Locke
authors: Department of Microbiology, University of Illinois, Urbana-Champaign, Urbana, Illinois, USA.
authors: Joseph R
authors: JR
authors: Weber
authors: Department of Biochemistry, University of Illinois, Urbana-Champaign, Urbana, Illinois, USA.
authors: Sheila M
authors: SM
authors: Egan
authors: Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois, USA Energy Biosciences Institute, University of Illinois, Urbana-Champaign, Urbana, Illinois, USA Department of Animal Sciences, University of Illinois, Urbana-Champaign, Urbana, Illinois, USA.
authors: Roderick I
authors: RI
authors: Mackie
authors: Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois, USA Energy Biosciences Institute, University of Illinois, Urbana-Champaign, Urbana, Illinois, USA Department of Biochemistry, University of Illinois, Urbana-Champaign, Urbana, Illinois, USA Department of Animal Sciences, University of Illinois, Urbana-Champaign, Urbana, Illinois, USA.
authors: Isaac
authors: I
authors: Cann
authors: Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois, USA Department of Geology, University of Illinois, Urbana-Champaign, Champaign, Illinois, USA Energy Biosciences Institute, University of Illinois, Urbana-Champaign, Urbana, Illinois, USA Department of Microbiology, University of Illinois, Urbana-Champaign, Urbana, Illinois, USA Department of Animal Sciences, University of Illinois, Urbana-Champaign, Urbana, Illinois, USA.
authors: Bruce W
authors: BW
authors: Fouke
mesh_terms: D015373:Bacterial Typing Techniques; D004269:DNA, Bacterial / Q000235:genetics; D004275:DNA, Ribosomal; D005290:Ferric Compounds / Q000378:metabolism; D000068536:Bacillota / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D020459:Genes, rRNA; D016680:Genome, Bacterial; D045302:Geobacter / Q000378:metabolism; D019015:Geologic Sediments / Q000382:microbiology*; D058085:Iron Compounds / Q000378:metabolism; D008670:Metals / Q000378:metabolism*; D008903:Minerals / Q000378:metabolism; D010084:Oxidation-Reduction; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S; D020592:Shewanella / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D005290:Ferric Compounds; D058085:Iron Compounds; D008670:Metals; D008903:Minerals; D012336:RNA, Ribosomal, 16S; C094886:goethite; C000499:ferric oxide; C092844:ferric oxyhydroxide