Centimeter-long electron transport in marine sediments via conductive minerals.

TitleCentimeter-long electron transport in marine sediments via conductive minerals.
Publication TypeJournal Article
Year of Publication2015
AuthorsMalvankar NS, King GM, Lovley DR
JournalISME J
Date Published2015 Feb
KeywordsElectron Transport, Geologic Sediments, Iron, Minerals, Oxidation-Reduction, Sulfides

Centimeter-long electron conduction through marine sediments, in which electrons derived from sulfide in anoxic sediments are transported to oxygen in surficial sediments, may have an important influence on sediment geochemistry. Filamentous bacteria have been proposed to mediate the electron transport, but the filament conductivity could not be verified and other mechanisms are possible. Surprisingly, previous investigations have never actually measured the sediment conductivity or its basic physical properties. Here we report direct measurements that demonstrate centimeter-long electron flow through marine sediments, with conductivities sufficient to account for previously estimated electron fluxes. Conductivity was lost for oxidized sediments, which contrasts with the previously described increase in the conductivity of microbial biofilms upon oxidation. Adding pyrite to the sediments significantly enhanced the conductivity. These results suggest that the role of conductive minerals, which are more commonly found in sediments than centimeter-long microbial filaments, need to be considered when modeling marine sediment biogeochemistry.

Alternate JournalISME J
PubMed ID25050525
PubMed Central IDPMC4303629