title: Hydrocarbon-related microbial processes in the deep sediments of the Eastern Mediterranean Levantine Basin.
abstract: During the 2011 exploration season of the EV Nautilus in the Mediterranean Sea, we conducted a multidisciplinary study, aimed at exploring the microbial populations below the sediment-water interface (SWI) in the hydrocarbon-rich environments of the Levantine basin. Two c. 1000-m-deep locations were sampled: sediments fueled by methane seepage at the toe of the Palmachim disturbance and a patch of euxinic sediment with high sulfide and methane content offshore Acre, enriched by hydrocarbon from an unknown source. We describe the composition of the microbial population in the top 5 cm of the sediment with 1 cm resolution, accompanied by measurements of methane and sulfate concentrations, and the isotopic composition of this methane and sulfate (δ¹³C(CH₄), δ¹⁸O(SO₄), and δ³⁴S(SO₄)). Our geochemical and microbiological results indicate the presence of the anaerobic methane oxidation (AOM) coupled to bacterial sulfate reduction (BSR). We show that complex methane and sulfur metabolizing microbial populations are present in both locations, although their community structure and metabolic preferences differ due to potential variation in the hydrocarbon source.
authors.affiliation: The Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel.
authors.forename: Maxim
authors.initials: M
authors.lastname: Rubin-Blum
authors.forename: Gilad
authors.initials: G
authors.lastname: Antler
authors.forename: Alexandra V
authors.initials: AV
authors.lastname: Turchyn
authors.forename: Rami
authors.initials: R
authors.lastname: Tsadok
authors.forename: Beverly N
authors.initials: BN
authors.lastname: Goodman-Tchernov
authors.forename: Eli
authors.initials: E
authors.lastname: Shemesh
authors.forename: James A
authors.initials: JA
authors.lastname: Austin
authors.forename: Dwight F
authors.initials: DF
authors.lastname: Coleman
authors.forename: Yizhaq
authors.initials: Y
authors.lastname: Makovsky
authors.forename: Orit
authors.initials: O
authors.lastname: Sivan
authors.forename: Dan
authors.initials: D
authors.lastname: Tchernov
mesh_terms: D001105:Archaea / Q000145:classification / Q000378:metabolism; D001419:Bacteria / Q000145:classification / Q000378:metabolism; D002247:Carbon Isotopes / Q000032:analysis; D019641:DNA, Archaeal / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D019015:Geologic Sediments / Q000737:chemistry / Q000382:microbiology*; D008522:Mediterranean Sea; D008697:Methane / Q000378:metabolism*; D010084:Oxidation-Reduction; D010103:Oxygen Isotopes / Q000032:analysis; D010802:Phylogeny; D013431:Sulfates / Q000378:metabolism*; D013460:Sulfur Isotopes / Q000032:analysis
chemical_list: D002247:Carbon Isotopes; D019641:DNA, Archaeal; D004269:DNA, Bacterial; D010103:Oxygen Isotopes; D013431:Sulfates; D013460:Sulfur Isotopes; D008697:Methane
keywords: Mediterranean Sea; Nautilus 
  EV; anaerobic oxidation of methane; hydrocarbon seepage; isotopic fractionation; sulfate-reducing bacteria