Fate of Cd during Microbial Fe(III) Mineral Reduction by a Novel and Cd-Tolerant Geobacter Species

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• 作者：E. Marie Muehe ; Martin Obst ; Adam Hitchcock ; Tolek Tyliszczak ; Sebastian Behrens ; Christian Schr枚der ; James M. Byrne ; F. Marc Michel ; Ute Kr盲mer ; Andreas Kappler
• 刊名：Environmental Science & Technology
• 出版年：2013
• 出版时间：December 17, 2013
• 年：2013
• 卷：47
• 期：24
• 页码：14099-14109
• 全文大小：691K
• 年卷期：v.47,no.24(December 17, 2013)
• ISSN：1520-5851

文摘

Fe(III) (oxyhydr)oxides affect the mobility of contaminants in the environment by providing reactive surfaces for sorption. This includes the toxic metal cadmium (Cd), which prevails in agricultural soils and is taken up by crops. Fe(III)-reducing bacteria can mobilize such contaminants by Fe(III) mineral dissolution or immobilize them by sorption to or coprecipitation with secondary Fe minerals. To date, not much is known about the fate of Fe(III) mineral-associated Cd during microbial Fe(III) reduction. Here, we describe the isolation of a new Geobacter sp. strain Cd1 from a Cd-contaminated field site, where the strain accounts for 10p>4p> cells gp>鈥?p> dry soil. Strain Cd1 reduces the poorly crystalline Fe(III) oxyhydroxide ferrihydrite in the presence of at least up to 112 mg Cd Lp>鈥?p>. During initial microbial reduction of Cd-loaded ferrihydrite, sorbed Cd was mobilized. However, during continuous microbial Fe(III) reduction, Cd was immobilized by sorption to and/or coprecipitation within newly formed secondary minerals that contained Ca, Fe, and carbonate, implying the formation of an otavite-siderite-calcite (CdCO₃鈥揊eCO₃鈥揅aCO₃) mixed mineral phase. Our data shows that microbially mediated turnover of Fe minerals affects the mobility of Cd in soils, potentially altering the dynamics of Cd uptake into food or phyto-remediating plants.