Microbial mediated formation of Fe-carbonate minerals under extreme acidic conditions

• DOI: 10.1038/srep04767
• Publication Date: 2014-04-23T09:20:55Z
• Authors: Mónica Sánchez-Román; David Fernández-R...; Ricardo Amils; Antonio Sánchez-N...; Thomas Schmid; Patxi San Martin-...; Nuria Rodríguez; Judith A. McKenzie; Crisogono Vasconc...
• Keywords: Geologic Sediments; Minerals; Iron; Carbonates; Química; Hydrogen-Ion Concentration; 01 natural sciences; Article; 13. Climate action; Meteoritics; Planetary science; SDG 14 - Life Below Water; Planetary sciences; Planetary sciences; Meteoritics; 0105 earth and related environmental sciences

Discovery of Fe-carbonate precipitation in Rio Tinto, a shallow river with very acidic waters, situated in Huelva, South-western Spain, adds a new dimension to our understanding of carbonate formation. Sediment samples from this low-pH system indicate that carbonates are formed in physico-chemical conditions ranging from acid to neutral pH. Evidence for microbial mediation is observed in secondary electron images (Fig. 1), which reveal rod-shaped bacteria embedded in the surface of siderite nanocrystals. The formation of carbonates in Rio Tinto is related to the microbial reduction of ferric iron coupled to the oxidation of organic compounds. Herein, we demonstrate for the first time, that Acidiphilium sp. PM, an iron-reducing bacterium isolated from Rio Tinto, mediates the precipitation of siderite (FeCO3) under acidic conditions and at a low temperature (30°C). We describe nucleation of siderite on nanoglobules in intimate association with the bacteria cell surface. This study has major implications for understanding carbonate formation on the ancient Earth or extraterrestrial planets.<br/>Scientific Reports, 4<br/>ISSN:2045-2322<br/>