Publication Date:
2010-02-26
Description:
Some bacteria are capable of extracellular electron transfer, thereby enabling them to use electron acceptors and donors without direct cell contact. Beyond the micrometre scale, however, no firm evidence has previously existed that spatially segregated biogeochemical processes can be coupled by electric currents in nature. Here we provide evidence that electric currents running through defaunated sediment couple oxygen consumption at the sediment surface to oxidation of hydrogen sulphide and organic carbon deep within the sediment. Altering the oxygen concentration in the sea water overlying the sediment resulted in a rapid (〈1-h) change in the hydrogen sulphide concentration within the sediment more than 12 mm below the oxic zone, a change explicable by transmission of electrons but not by diffusion of molecules. Mass balances indicated that more than 40% of total oxygen consumption in the sediment was driven by electrons conducted from the anoxic zone. A distinct pH peak in the oxic zone could be explained by electrochemical oxygen reduction, but not by any conventional sets of aerobic sediment processes. We suggest that the electric current was conducted by bacterial nanowires combined with pyrite, soluble electron shuttles and outer-membrane cytochromes. Electrical communication between distant chemical and biological processes in nature adds a new dimension to our understanding of biogeochemistry and microbial ecology.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Nielsen, Lars Peter -- Risgaard-Petersen, Nils -- Fossing, Henrik -- Christensen, Peter Bondo -- Sayama, Mikio -- England -- Nature. 2010 Feb 25;463(7284):1071-4. doi: 10.1038/nature08790.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biological Sciences, Aarhus University, Ny Munkegade 114, DK-8000 Aarhus C, Denmark. biolpn@biology.au.dk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20182510" target="_blank"〉PubMed〈/a〉
Keywords:
Bacteria/metabolism
;
Cytochromes/metabolism
;
Denmark
;
Diffusion
;
*Electric Conductivity
;
Electrochemistry
;
Electron Transport
;
Electrons
;
Geologic Sediments/*chemistry/*microbiology
;
Hydrogen Sulfide/analysis/chemistry
;
Hydrogen-Ion Concentration
;
Iron/chemistry
;
Nanowires/microbiology
;
Oxygen/analysis/metabolism
;
Oxygen Consumption
;
Porosity
;
Seawater/*microbiology
;
Sulfides/chemistry
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
,
Natural Sciences in General
,
Physics
