Journal
SCIENCE OF THE TOTAL ENVIRONMENT
Volume 688, Issue -, Pages 664-672Publisher
ELSEVIER
DOI: 10.1016/j.scitotenv.2019.06.299
Keywords
Anaerobic methane oxidation; Electron shuttle; Iron reduction; DNA-based stable isotope probing; Metagenomics
Categories
Funding
- Natural Science Foundation of China [41701270]
- Natural Science Foundation of Fujian Province, China [2019J01394]
- Key Technologies R&D Program of Fujian Province [2017NZ0001-1]
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Anaerobic oxidation of methane (AOM) has recently been coupled with the reduction of insoluble electron acceptors such as iron minerals. However, effects of electron shuttles (ESs) on this process and the underlying coupling mechanisms remain not well understood. Here, we evaluated MN-coupled ferrihydrite reduction by a mixed culture in the absence and presence of ESs. The results showed that ESs (AQS, Gavin, HA and AQDS) significantly enhanced the rate (up to 7.4 times) of AOM-dependent ferrihydrite reduction compared with the control. The enhancements were linearly related with the electron transfer capacity of ESs. Illumina high-throughput sequencing and DNA-based stable isotope probing revealed that the MN-coupled iron reduction depended on the syntrophic interaction of Methanobacterium and the partner bacteria. Methanobacterium as the dominant microorganism, did not assimilate methane into its biomasses. However, it played a crucial role in the partial oxidation of methane into an intermediate (i.e. propionate), which was then assimilated by the partner bacteria (e.g. Cellulomonas, Desulfovibrio, Actinotalea, etc.) for ferrihydrite reduction. This work suggests that ESs in natural environments can mitigate the methane emissions by facilitating the AOM process and biogeochemical cycles of iron. (C) 2019 Elsevier B.V. All rights reserved.
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