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Shifting microbial communities sustain multiyear iron reduction and methanogenesis in ferruginous sediment incubations
Author(s) -
Bray M. S.,
Wu J.,
Reed B. C.,
Kretz C. B.,
Belli K. M.,
Simister R. L.,
Henny C.,
Stewart F. J.,
DiChristina T. J.,
Brandes J. A.,
Fowle D. A.,
Crowe S. A.,
Glass J. B.
Publication year - 2017
Publication title -
geobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.859
H-Index - 72
eISSN - 1472-4669
pISSN - 1472-4677
DOI - 10.1111/gbi.12239
Subject(s) - methanogenesis , ferrihydrite , environmental chemistry , goethite , anoxic waters , chemistry , methane , anaerobic oxidation of methane , methanomicrobiales , methanosarcina , organic chemistry , adsorption
Reactive Fe( III ) minerals can influence methane ( CH 4 ) emissions by inhibiting microbial methanogenesis or by stimulating anaerobic CH 4 oxidation. The balance between Fe( III ) reduction, methanogenesis, and CH 4 oxidation in ferruginous Archean and Paleoproterozoic oceans would have controlled CH 4 fluxes to the atmosphere, thereby regulating the capacity for CH 4 to warm the early Earth under the Faint Young Sun. We studied CH 4 and Fe cycling in anoxic incubations of ferruginous sediment from the ancient ocean analogue Lake Matano, Indonesia, over three successive transfers (500 days in total). Iron reduction, methanogenesis, CH 4 oxidation, and microbial taxonomy were monitored in treatments amended with ferrihydrite or goethite. After three dilutions, Fe( III ) reduction persisted only in bottles with ferrihydrite. Enhanced CH 4 production was observed in the presence of goethite, highlighting the potential for reactive Fe( III ) oxides to inhibit methanogenesis. Supplementing the media with hydrogen, nickel and selenium did not stimulate methanogenesis. There was limited evidence for Fe( III )‐dependent CH 4 oxidation, although some incubations displayed CH 4 ‐stimulated Fe( III ) reduction. 16S rRNA profiles continuously changed over the course of enrichment, with ultimate dominance of unclassified members of the order Desulfuromonadales in all treatments. Microbial diversity decreased markedly over the course of incubation, with subtle differences between ferrihydrite and goethite amendments. These results suggest that Fe( III ) oxide mineralogy and availability of electron donors could have led to spatial separation of Fe( III )‐reducing and methanogenic microbial communities in ferruginous marine sediments, potentially explaining the persistence of CH 4 as a greenhouse gas throughout the first half of Earth history.