title: Molecular diversity of sulfate-reducing bacteria from two different continental margin habitats.
abstract: This study examined the natural diversity and distributions of sulfate-reducing bacteria along a natural carbon gradient extending down the shelf-slope transition zone of the eastern Pacific continental margin. Dissimilatory (bi)sulfite reductase gene sequences (dsrAB) were PCR amplified and cloned from five different sampling sites, each at a discrete depth, from two different margin systems, one off the Pacific coast of Mexico and another off the coast of Washington State. A total of 1,762 clones were recovered and evaluated by restriction fragment length polymorphism (RFLP) analysis. The majority of the gene sequences recovered showed site and depth restricted distributions; however, a limited number of gene sequences were widely distributed within and between the margin systems. Cluster analysis identified 175 unique RFLP patterns, and nucleotide sequences were determined for corresponding clones. Several different continental margin DsrA sequences clustered with those from formally characterized taxa belonging to the delta subdivision of the class Proteobacteria (Desulfobulbus propionicus, Desulfosarcina variabilis) and the Bacillus-Clostridium (Desulfotomaculum putei) divisions, although the majority of the recovered sequences were phylogenetically divergent relative to all of the other DsrA sequences available for comparison. This study revealed extensive new genetic diversity among sulfate-reducing bacteria in continental margin sedimentary habitats, which appears to be tightly coupled to slope depth, specifically carbon bioavailability.
authors.affiliation: Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: Xueduan
authors.initials: X
authors.lastname: Liu
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Bagwell
authors.forename: Liyou
authors.initials: L
authors.lastname: Wu
authors.forename: Allan H
authors.initials: AH
authors.lastname: Devol
authors.forename: Jizhong
authors.initials: J
authors.lastname: Zhou
mesh_terms: D020564:Deltaproteobacteria / Q000145:classification / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification; D004777:Environment; D014644:Genetic Variation; D019015:Geologic Sediments / Q000382:microbiology; D050885:Hydrogensulfite Reductase; D008800:Mexico; D008969:Molecular Sequence Data; D050862:Oxidoreductases Acting on Sulfur Group Donors / Q000235:genetics; D010140:Pacific Ocean; D010802:Phylogeny; D012150:Polymorphism, Restriction Fragment Length; D012623:Seawater / Q000382:microbiology; D017422:Sequence Analysis, DNA; D013431:Sulfates / Q000378:metabolism; D016999:Sulfur-Reducing Bacteria / Q000145:classification* / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification; D014861:Washington
chemical_list: D013431:Sulfates; D050862:Oxidoreductases Acting on Sulfur Group Donors; D050885:Hydrogensulfite Reductase