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Science 18 September 2009:
Vol. 325. no. 5947, pp. 1541 - 1544
DOI: 10.1126/science.1174012
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Reports

A Constant Flux of Diverse Thermophilic Bacteria into the Cold Arctic Seabed

Casey Hubert,1,* Alexander Loy,2 Maren Nickel,1 Carol Arnosti,3 Christian Baranyi,2 Volker Brüchert,1,{dagger} Timothy Ferdelman,1 Kai Finster,4 Flemming Mønsted Christensen,4,5 Júlia Rosa de Rezende,1,5 Verona Vandieken,1,{ddagger} Bo Barker Jørgensen1,5

Microorganisms have been repeatedly discovered in environments that do not support their metabolic activity. Identifying and quantifying these misplaced organisms can reveal dispersal mechanisms that shape natural microbial diversity. Using endospore germination experiments, we estimated a stable supply of thermophilic bacteria into permanently cold Arctic marine sediment at a rate exceeding 108 spores per square meter per year. These metabolically and phylogenetically diverse Firmicutes show no detectable activity at cold in situ temperatures but rapidly mineralize organic matter by hydrolysis, fermentation, and sulfate reduction upon induction at 50°C. The closest relatives to these bacteria come from warm subsurface petroleum reservoir and ocean crust ecosystems, suggesting that seabed fluid flow from these environments is delivering thermophiles to the cold ocean. These transport pathways may broadly influence microbial community composition in the marine environment.

1 Biogeochemistry Group, Max Planck Institute for Marine Microbiology, Celsiusstrasse 1, D-28359 Bremen, Germany.
2 Department of Microbial Ecology, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria.
3 Department of Marine Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599–3300, USA.
4 Department of Biological Sciences–Microbiology Section, Aarhus University, Ny Munkegade, Building 1540, DK-8000 Aarhus C, Denmark.
5 Center for Geomicrobiology, Department of Biological Sciences, Aarhus University, Ny Munkegade, Building 1535, DK-8000 Aarhus C, Denmark.

{dagger} Present address: Department of Geology and Geochemistry, Stockholm University, Svante Arrhenius Väg 8C, 106 91 Stockholm, Sweden.

{ddagger} Present address: Institute of Biology, University of Southern Denmark, Campusvej 55, 5320 Odense M Denmark.

* To whom correspondence should be addressed. E-mail: chubert{at}mpi-bremen.de

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
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D. J. Patterson (2009)
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