Biogeochemistry and community composition of iron- and sulfur-precipitating microbial mats at the Chefren mud volcano (Nile Deep Sea fan, Eastern Mediterranean)
|Author(s)||Omoregie E1, 2, Mastalerz V3, De Lange G3, Straub K4, Kappler A4, Roy H1, Stadnitskaia A5, Foucher Jean-Paul6, Boetius A1, 2, 7|
|Affiliation(s)||1 : Max Planck Inst Marine Micorbiol, Bremen, Germany.
2 : Jacobs Univ, Bremen, Germany.
3 : Univ Utrecht, Dept Earth Sci, Utrecht, Netherlands.
4 : Univ Tubingen, Ctr Appl Geosci, Tubingen, Germany.
5 : Royal Netherlands Inst Sea Res, Texel, Netherlands.
6 : IFREMER, Ctr Brest, Dept Marine Geosci, Plouzane, France.
7 : Alfred Wegener Inst Polar & Marine Res, D-2850 Bremerhaven, Germany.
|Source||Applied and environmental microbiology (0099-2240) (American society for microbiology), 2008-05 , Vol. 74 , N. 10 , P. 3198-3215|
|WOS© Times Cited||98|
|Keyword(s)||gulf of mexico, sulfate reducing bacteria, egyptian continental margin, northeast pacific ocean, ribosomal rna sequences, in situ hybridization, anaerobic oxidation, marine sediments, gas hydrate, oxiding bacteria|
|Abstract||In this study we determined the composition and biogeochemistry of novel, brightly colored, white and orange microbial mats at the surface of a brine seep at the outer rim of the Chefren mud volcano. These mats were interspersed with one another, but their underlying sediment biogeochemistries differed considerably. Microscopy revealed that the white mats were granules composed of elemental S filaments, similar to those produced by the sulfide-oxidizing epsilonproteobacterium "Candidatus Arcobacter sulfidicus." Fluorescence in situ hybridization indicated that microorganisms targeted by a "Ca. Arcobacter sulfidicus"-specific oligonucleotide probe constituted up to 24% of the total the cells within these mats. Several 16S rRNA gene sequences from organisms closely related to "Ca. Arcobacter suifidicus" were identified. In contrast, the orange mat consisted mostly of bright orange flakes composed of empty Fe(III) (hydr)oxide-coated microbial sheaths, similar to those produced by the neutrophilic Fe(II)-oxidizing betaproteobacterium Leptothrix ochracea. None of the 16S rRNA gene sequences obtained from these samples were closely related to sequences of known neutrophilic aerobic Fe (II)-oxidizing bacteria. The sediments below both types of mats showed relatively high sulfate reduction rates (300 nmol center dot cm(-3) center dot day(-1)) partially fueled by the anaerobic oxidation of methane (10 to 20 nmol center dot cm(-3) center dot day(-1)). Free sulfide produced below the white mat was depleted by sulfide oxidation within the mat itself. Below the orange mat free Fe(II) reached the surface layer and was depleted in part by microbial Fe(II) oxidation. Both mats and the sediments underneath them hosted very diverse microbial communities and contained mineral precipitates, most likely due to differences in fluid flow patterns.|