Orenia metallireducens sp. nov. strain Z6, a novel metal-reducing member of the phylum Firmicutes from the deep subsurface

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... Full description

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Bibliographic Details
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doi: 10.1128/AEM.02382-16
Authors:Dong, Y.; Sanford, R.A.; Boyanov, M.I.; Kemner, K.M.; Flynn, T.M.; O'Loughlin, E.J.; Chang, Y.; Locke, R.A., Jr.; Weber, J.R.; Egan, S.M.; Mackie, R.I.; Cann, I.; Fouke, B.W.
Volume Title:Applied and Environmental Microbiology
Source:Applied and Environmental Microbiology, 82(21), p.6440-6453. Publisher: American Society for Microbiology, Washington, DC, United States. ISSN: 0099-2240
Publication Date:2016
Note:In English. 86 refs.; illus., incl. 2 tables
Subjects:Bacteria; Boreholes; Crystallization; Electron microscopy data; Geobacter; Goethite; Ground water; Hematite; Iron oxides; Metabolism; Oxides; SEM data; Shewanella; Spectra; TEM data; X-ray spectra; Illinois Basin; United States; Firmicutes; Orenia; Orenia metallireducens
Record ID:2020024177
Copyright Information:GeoRef, Copyright 2020 American Geosciences Institute.
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Description
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 H2 as 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.