Fate of Cd during microbial Fe(III) mineral reduction by a novel and Cd-tolerant Geobacter species


Muehe EM, Obst M, Hitchcock A, Tyliszczak T, Behrens S, Schröder C, Byrne JM, Michel FM, Kramer U & Kappler A (2013) Fate of Cd during microbial Fe(III) mineral reduction by a novel and Cd-tolerant Geobacter species. Environmental Science and Technology, 47 (24), pp. 14099-14109.;

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 co-precipitation 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 104 cells g-1 dry soil. Strain Cd1 reduces the poorly-crystalline Fe(III) oxyhydroxide ferrihydrite in the presence of at least up to 112 mg Cd L-1. 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 co-precipitation within newly formed secondary minerals that contained Ca, Fe and carbonate, implying the formation of an otavite-siderite-calcite (CdCO3-FeCO3-CaCO3) 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.

Environmental Science and Technology: Volume 47, Issue 24

Publication date31/12/2013
Publication date online25/11/2013
Date accepted by journal25/11/2013
PublisherAmerican Chemical Society
Publisher URL