RT Journal Article
SR Electronic
T1 Shifting microbial communities sustain multi-year iron reduction and methanogenesis in ferruginous sediment incubations
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 087783
DO 10.1101/087783
A1 Marcus S. Bray
A1 Jieying Wu
A1 Benjamin C. Reed
A1 Cecilia B. Kretz
A1 Keaton M. Belli
A1 Rachel L. Simister
A1 Cynthia Henny
A1 Frank J. Stewart
A1 Thomas J. DiChristina
A1 Jay A. Brandes
A1 David A. Fowle
A1 Sean A. Crowe
A1 Jennifer B. Glass
YR 2017
UL http://biorxiv.org/content/early/2017/02/13/087783.abstract
AB Reactive Fe(III) minerals can influence methane (CH4) emissions by inhibiting microbial methanogenesis or by stimulating anaerobic CH4 oxidation. The balance between Fe(III) reduction, methanogenesis, and methane oxidation in ferruginous Archean and Paleoproterozoic oceans would have controlled CH4 fluxes to the atmosphere, thereby regulating the capacity for CH4 to warm the early Earth under the Faint Young Sun. We studied CH4 and Fe cycling in anoxic incubations of ferruginous sediment from the ancient ocean analogue Lake Matano, Indonesia over three successive transfers (500 days total). Iron reduction, methanogenesis, methane 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 CH4 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 CH4 oxidation, although some incubations displayed CH4-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 CH4 as a greenhouse gas throughout the first half of Earth history.