Biosciences Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439, USA. Computation Institute, University of Chicago, Chicago, IL 60637, USA.
Biosciences Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439, USA.
Science. 2014 May 30;344(6187):1039-42. doi: 10.1126/science.1252066. Epub 2014 May 1.
Microbial reduction of ferric iron [Fe(III)] is an important biogeochemical process in anoxic aquifers. Depending on groundwater pH, dissimilatory metal-reducing bacteria can also respire alternative electron acceptors to survive, including elemental sulfur (S(0)). To understand the interplay of Fe/S cycling under alkaline conditions, we combined thermodynamic geochemical modeling with bioreactor experiments using Shewanella oneidensis MR-1. Under these conditions, S. oneidensis can enzymatically reduce S(0) but not goethite (α-FeOOH). The HS(-) produced subsequently reduces goethite abiotically. Because of the prevalence of alkaline conditions in many aquifers, Fe(III) reduction may thus proceed via S(0)-mediated electron-shuttling pathways.
微生物还原三价铁（Fe(III)）是缺氧含水层中一种重要的生物地球化学过程。根据地下水的 pH 值，异化金属还原菌也可以通过呼吸替代电子受体来存活，包括元素硫（S(0)）。为了了解碱性条件下 Fe/S 循环的相互作用，我们结合热力学地球化学模型和使用 Shewanella oneidensis MR-1 的生物反应器实验进行了研究。在这些条件下，Shewanella oneidensis 可以酶促还原 S(0)但不能还原针铁矿（α-FeOOH）。随后产生的 HS(-)会非生物还原针铁矿。由于许多含水层中普遍存在碱性条件，因此 Fe(III)的还原可能通过 S(0)介导的电子穿梭途径进行。
