title: Iron reduction in the DAMO/Shewanella oneidensis MR-1 coculture system and the fate of Fe(II).
abstract: 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.
authors.affiliation: CAS Key Laboratory for Urban Pollutant Conversion, Department of Chemistry, University of Science and Technology of China, Hefei, 230026, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Fu
authors.affiliation: CAS Key Laboratory for Urban Pollutant Conversion, Department of Chemistry, University of Science and Technology of China, Hefei, 230026, China.
authors.forename: Shan-Wei
authors.initials: SW
authors.lastname: Li
authors.affiliation: CAS Key Laboratory for Urban Pollutant Conversion, Department of Chemistry, University of Science and Technology of China, Hefei, 230026, China.
authors.forename: Zhao-Wei
authors.initials: ZW
authors.lastname: Ding
authors.affiliation: 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.
authors.forename: Jing
authors.initials: J
authors.lastname: Ding
authors.affiliation: CAS Key Laboratory for Urban Pollutant Conversion, Department of Chemistry, University of Science and Technology of China, Hefei, 230026, China.
authors.forename: Yong-Ze
authors.initials: YZ
authors.lastname: Lu
authors.affiliation: 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. Electronic address: rzeng@ustc.edu.cn.
authors.forename: Raymond J
authors.initials: RJ
authors.lastname: Zeng
mesh_terms: D001419:Bacteria / Q000378:metabolism*; D058440:Denitrification; D005290:Ferric Compounds / Q000378:metabolism*; D005296:Ferrous Compounds / Q000378:metabolism; D008697:Methane / Q000378:metabolism; D010084:Oxidation-Reduction; D020592:Shewanella / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D005290:Ferric Compounds; D005296:Ferrous Compounds; D014874:Water Pollutants, Chemical; C092844:ferric oxyhydroxide; D008697:Methane
keywords: Coculture; Denitrifying anaerobic methane oxidation; Ferrihydrite bioreduction; Secondary minerals; Shewanella oneidensis MR-1