Advanced Water Management Centre, The University of Queensland, St Lucia, Brisbane, Queensland, 4072, Australia.
Advanced Water Management Centre, The University of Queensland, St Lucia, Brisbane, Queensland, 4072, Australia.
Water Res. 2020 Sep 15;183:116008. doi: 10.1016/j.watres.2020.116008. Epub 2020 Jun 13.
Selenate (Se(VI)) contamination in groundwater is one of major concerns for human health, in particular in shale gas extraction sites. Microbial selenate reduction coupled to methane (CH) oxidation has been demonstrated very recently. Little is known whether ethane (CH) and butane (CH) are able to drive selenate reduction, although they are also important components in shale gas. In this study, we demonstrated Se(VI) bio-reduction could be achieved using CH and CH as electron donors and carbon sources. Scanning electron microscopy coupled to energy dispersive X-ray spectroscopy (SEM-EDX) confirmed elemental Se (Se) was the major final product formed from Se(VI) bio-reduction. Polyhydroxyalkanoates (PHAs) were generated in the biofilms as the internal electron-storage materials, which were consumed for sustaining Se(VI) bio-reduction in absence of CH and CH. Microbial community analysis showed that two genera capable of oxidizing gaseous alkanes dominated in the biofilms, including Mycobacterium (in both CH and CH-fed biofilms) and Rhodococcus (in CH-fed biofilm). In addition, several potential Se(VI) reducers (e.g., Variovorax) were detected in the biofilms. Investigation of Communities by Reconstruction of Unobserved States analysis supported that predictive genes associated with alkanes oxidation, denitrification and PHAs cycle were enriched in the biofilms. These findings offer insights into the process of selenate reduction driven by CH and CH, which ultimately may help to develop a solution to use shale gas for groundwater remediation, especially near shale gas exploitation sites.
地下水中的硒酸盐（Se(VI)）污染是人类健康的主要关注点之一，特别是在页岩气开采区。最近已经证明，微生物硒酸盐还原与甲烷（CH）氧化偶联。虽然乙烷（CH）和丁烷（CH）也是页岩气中的重要成分，但它们是否能够驱动硒酸盐还原还知之甚少。在这项研究中，我们证明了可以使用 CH 和 CH 作为电子供体和碳源来实现 Se(VI)的生物还原。扫描电子显微镜结合能量色散 X 射线光谱（SEM-EDX）证实，从 Se(VI)生物还原中形成的主要最终产物是元素硒（Se）。生物膜中生成了聚羟基烷酸酯（PHAs）作为内部电子储存材料，当 CH 和 CH 不存在时，这些材料被消耗以维持 Se(VI)的生物还原。微生物群落分析表明，两种能够氧化气态烷烃的属在生物膜中占主导地位，包括分枝杆菌（在 CH 和 CH 喂养的生物膜中）和红球菌（在 CH 喂养的生物膜中）。此外，在生物膜中还检测到了几个潜在的 Se(VI)还原剂（例如，鞘氨醇单胞菌）。未观察状态重建的群落分析表明，与烷烃氧化、反硝化和 PHAs 循环相关的预测基因在生物膜中富集。这些发现为 CH 和 CH 驱动的硒酸盐还原过程提供了深入了解，这最终可能有助于开发利用页岩气进行地下水修复的解决方案，特别是在页岩气开采区附近。
