Anaerobic degradation of cyclohexane by sulfate-reducing bacteria from hydrocarbon-contaminated marine sediments

Several strains of sulfate-reducing bacteria were isolated from marine sediments recovered near Tunis, Korbous and Bizerte, Tunisia. They all showed characteristics consistent with members of the genus Desulfovibrio. One of these strains, designated MB3T, was characterized further. Cells of strain MB3T were slender, curved, vibrio-shaped, motile, Gram-negative, non-spore-forming rods. They were positive for desulfoviridin as bisulfite reductase. Strain MB3T grew at temperatures of 15–45 °C (optimum 40 °C) and at pH 6.0–8.1 (optimum pH 7.0). NaCl was required for growth (optimum 20 g NaCl l−1). Strain MB3T utilized H2 in the presence of acetate with sulfate as electron acceptor. It also utilized lactate, ethanol, pyruvate, malate, fumarate, succinate, butanol and propanol as electron donors. Lactate was oxidized incompletely to acetate. Strain MB3T fermented pyruvate and fumarate (poorly). Electron acceptors utilized included sulfate, sulfite, thiosulfate, elemental sulfur and fumarate, but not nitrate or nitrite. The G+C content of the genomic DNA was 51 mol%. On the basis of genotypic, phenotypic and phylogenetic characteristics, strain MB3T (=DSM 18034T=NCIMB 14199T) is proposed as the type strain of a novel species, Desulfovibrio bizertensis sp. nov.

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Comparative Analysis of Methane-Oxidizing Archaea and Sulfate-Reducing Bacteria in Anoxic Marine Sediments

Applied and Environmental Microbiology ◽

10.1128/aem.67.4.1922-1934.2001 ◽

2001 ◽

Vol 67 (4) ◽

pp. 1922-1934 ◽

Cited By ~ 454

Author(s):

V. J. Orphan ◽

K.-U. Hinrichs ◽

W. Ussler ◽

C. K. Paull ◽

L. T. Taylor ◽

...

Keyword(s):

Marine Sediments ◽

Sulfate Reducing Bacteria ◽

Rrna Gene ◽

Anaerobic Oxidation Of Methane ◽

Ether Lipids ◽

Methane Seep ◽

Sulfate Reducing ◽

Oxidation Of Methane ◽

Close Relatives ◽

Reducing Bacteria

ABSTRACT The oxidation of methane in anoxic marine sediments is thought to be mediated by a consortium of methane-consuming archaea and sulfate-reducing bacteria. In this study, we compared results of rRNA gene (rDNA) surveys and lipid analyses of archaea and bacteria associated with methane seep sediments from several different sites on the Californian continental margin. Two distinct archaeal lineages (ANME-1 and ANME-2), peripherally related to the orderMethanosarcinales, were consistently associated with methane seep marine sediments. The same sediments contained abundant13C-depleted archaeal lipids, indicating that one or both of these archaeal groups are members of anaerobic methane-oxidizing consortia. 13C-depleted lipids and the signature 16S rDNAs for these archaeal groups were absent in nearby control sediments. Concurrent surveys of bacterial rDNAs revealed a predominance of δ-proteobacteria, in particular, close relatives ofDesulfosarcina variabilis. Biomarker analyses of the same sediments showed bacterial fatty acids with strong 13C depletion that are likely products of these sulfate-reducing bacteria. Consistent with these observations, whole-cell fluorescent in situ hybridization revealed aggregations of ANME-2 archaea and sulfate-reducing Desulfosarcina andDesulfococcus species. Additionally, the presence of abundant 13C-depleted ether lipids, presumed to be of bacterial origin but unrelated to ether lipids of members of the orderDesulfosarcinales, suggests the participation of additional bacterial groups in the methane-oxidizing process. Although theDesulfosarcinales and ANME-2 consortia appear to participate in the anaerobic oxidation of methane in marine sediments, our data suggest that other bacteria and archaea are also involved in methane oxidation in these environments.

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