Recent studies postulated the viability of a suite of metabolic pathways in Enceladus’ ocean motivated by the detection of H2 and CO2 in the plumes – evidence for available free energy for methanogenesis driven by hydrothermal activity at the moon's seafloor. However, these have not yet been explored in detail. Here, a range of experiments were performed to investigate whether microbial iron reduction could be a viable metabolic pathway in the ocean by iron-reducing bacteria such as Geobacter sulfurreducens. This study has three main outcomes: (i) the successful reduction of a number of crystalline Fe(III)-bearing minerals predicted to be present at Enceladus was shown to take place to differing extents using acetate as an electron donor; (ii) substantial bacterial growth in a simulated Enceladus ocean medium was demonstrated using acetate and H2(g) separately as electron donors; (iii) microbial iron reduction of ferrihydrite was shown to partially occur at pH 9, the currently accepted value for Enceladus’ ocean, whilst being severely hindered at the ambient ocean temperature of 0°. This study proposes the possibilities for biogeochemical iron cycling in Enceladus’ ocean, suggesting that a strain of iron-reducing bacteria can effectively function under Enceladus-like conditions.

最近的研究假设了土卫二海洋中一系列代谢途径的可行性，其动机是检测到羽流中的 H 2和 CO 2 - 这证明了土卫二海底热液活动驱动的产甲烷作用存在可用的自由能。然而，这些尚未得到详细探讨。在这里，进行了一系列实验，以研究微生物铁还原是否可能是海洋中铁还原细菌（例如硫还原地杆菌）的可行代谢途径。这项研究有三个主要成果：(i) 使用乙酸盐作为电子供体，成功地在不同程度上还原了预计存在于土卫二的许多结晶含 Fe(III) 矿物；(ii) 分别使用乙酸盐和 H 2( g )作为电子供体，证明了模拟土卫二海洋介质中细菌的大量生长；(iii) 水铁矿的微生物铁还原被证明在 pH 值 9（目前土卫二海洋公认的值）下部分发生，同时在 0° 的环境海洋温度下受到严重阻碍。这项研究提出了土卫二海洋中生物地球化学铁循环的可能性，表明铁还原细菌菌株可以在类似土卫二的条件下有效发挥作用。