CAS Key Laboratory for Urban Pollutant Conversion, Department of Chemistry, University of Science and Technology of China, Hefei, 230026, China.
CAS Key Laboratory for Urban Pollutant Conversion, Department of Chemistry, University of Science and Technology of China, Hefei, 230026, China; Advanced Laboratory for Environmental Research and Technology, USTC-CityU, Suzhou, 215213, China.
Water Res. 2016 Jan 1;88:808-815. doi: 10.1016/j.watres.2015.11.011. Epub 2015 Nov 10.
Dissimilatory iron reduction and anaerobic methane oxidation processes play important roles in the global iron and carbon cycle, respectively. This study explored the ferrihydrite reduction process with methane as a carbon source in a coculture system of denitrifying anaerobic methane oxidation (DAMO) microbes enriched in laboratory and Shewanella oneidensis MR-1, and then characterized the reduced products. Ferrihydrite reduction was also studied in the DAMO and Shewanella systems alone. The ferrihydrite was reduced slightly (<13.3%) in the separate systems, but greatly (42.0-88.3%) in the coculture system. Isotope experiment of (13)CH4 addition revealed that DAMO microbes coupled to S. oneidensis MR-1 in a ferric iron reduction process with (13)CH4 consumption and (13)CO2 production. Compared with ferrihydrite, the reduced products showed increased crystallinity (from amorphous state to crystallinity 77.1%) and magnetism (from paramagnetic to ferromagnetic). The produced ferrous iron was formed into minerals primarily composed of siderite with a small amount vivianite and magnetite. A portion of products covered the cell surface and hindered further reactions. The results presented herein widen the current understanding of iron metabolism and mineralization in the ocean, and show that the coculture systems of DAMO microbes and Shewanella have the potential to be globally important to iron reduction and methane oxidation.
异化铁还原和厌氧甲烷氧化过程分别在全球铁碳循环中发挥重要作用。本研究探索了用甲烷作为碳源的共培养体系中脱氮厌氧甲烷氧化（DAMO）微生物富集实验室和希瓦氏菌 MR-1 中的水铁矿还原过程，然后对还原产物进行了表征。还单独研究了 DAMO 和希瓦氏菌系统中的水铁矿还原。在单独的系统中，水铁矿的还原程度较小（<13.3%），但在共培养系统中则较大（42.0-88.3%）。（13）CH4 添加的同位素实验表明，DAMO 微生物与 S. oneidensis MR-1 耦合，在铁还原过程中消耗（13）CH4 并产生（13）CO2。与水铁矿相比，还原产物的结晶度增加（从无定形状态到结晶度 77.1%）和磁性增强（从顺磁到铁磁）。生成的亚铁离子形成主要由菱铁矿组成的矿物，少量蓝铁矿和磁铁矿。部分产物覆盖在细胞表面，阻碍了进一步的反应。本研究结果拓宽了对海洋中铁代谢和矿化的现有认识，并表明 DAMO 微生物和希瓦氏菌的共培养体系可能对全球范围内的铁还原和甲烷氧化具有重要意义。
