Deep-sea hydrothermal vent Epsilonproteobacteria encode a conserved and widespread nitrate reduction pathway (Nap).

Despite the frequent isolation of nitrate-respiring Epsilonproteobacteria from deep-sea hydrothermal vents, the genes coding for the nitrate reduction pathway in these organisms have not been investigated in depth. In this study we have shown that the gene cluster coding for the periplasmic nitrate reductase complex (nap) is highly conserved in chemolithoautotrophic, nitrate-reducing Epsilonproteobacteria from deep-sea hydrothermal vents. Furthermore, we have shown that the napA gene is expressed in pure cultures of vent Epsilonproteobacteria and it is highly conserved in microbial communities collected from deep-sea vents characterized by different temperature and redox regimes.

Parvibaculum hydrocarboniclasticum sp. nov., a mesophilic, alkane-oxidizing alphaproteobacterium isolated from a deep-sea hydrothermal vent on the East Pacific Rise.

An aerobic, alkane-oxidizing bacterium, designated strain EPR92(T), was isolated from hydrothermal fluids that had been collected from a deep-sea vent on the East Pacific Rise (at 9° 50' N 104° 17' W). The cells of the novel strain were Gram-staining-negative rods that measured approximately 1.4 µm in length and 0.

Phorcysia thermohydrogeniphila gen. nov., sp. nov., a thermophilic, chemolithoautotrophic, nitrate-ammonifying bacterium from a deep-sea hydrothermal vent.

A novel hyperthermophilic, anaerobic, chemolithoautotrophic bacterium, designated strain HB-8(T), was isolated from the tube of Alvinella pompejana tubeworms collected from the wall of an actively venting sulfide structure on the East Pacific Rise at 13° N. The cells were Gram-negative rods, approximately 1.0-1.

Genetic diversity and demographic instability in Riftia pachyptila tubeworms from eastern Pacific hydrothermal vents.

Background: Deep-sea hydrothermal vent animals occupy patchy and ephemeral habitats supported by chemosynthetic primary production. Volcanic and tectonic activities controlling the turnover of these habitats contribute to demographic instability that erodes genetic variation within and among colonies of these animals. We examined DNA sequences from one mitochondrial and three nuclear gene loci to assess genetic diversity in the siboglinid tubeworm, Riftia pachyptila, a widely distributed constituent of vents along the East Pacific Rise and Galápagos Rift.

Salinisphaera hydrothermalis sp. nov., a mesophilic, halotolerant, facultatively autotrophic, thiosulfate-oxidizing gammaproteobacterium from deep-sea hydrothermal vents, and emended description of the genus Salinisphaera.

A mesophilic, aerobic, facultatively chemolithoautotrophic bacterium, designated strain EPR70(T), was isolated from hydrothermal fluids from diffuse-flow vents on the East Pacific Rise at degrees 50' N 10 degrees 17' W. Cells were Gram-negative rods, approximately 0.8-1.

Vertical distribution and diversity of bacteria and archaea in sulfide and methane-rich cold seep sediments located at the base of the Florida Escarpment.

The bacterial and archaeal communities of the sediments at the base of the Florida Escarpment (Gulf of Mexico, USA) were investigated using molecular phylogenetic analysis. The total microbial community DNA of each of three vertical zones (top, middle and bottom) of a sediment core was extracted and the 16S rRNA genes were amplified by PCR, cloned and sequenced. Shannon-Weaver Diversity measures of bacteria were high in all three zones.

Mercury adaptation among bacteria from a deep-sea hydrothermal vent.

Since deep-sea hydrothermal vent fluids are enriched with toxic metals, it was hypothesized that (i) the biota in the vicinity of a vent is adapted to life in the presence of toxic metals and (ii) metal toxicity is modulated by the steep physical-chemical gradients that occur when anoxic, hot fluids are mixed with cold oxygenated seawater. We collected bacterial biomass at different distances from a diffuse flow vent at 9 degrees N on the East Pacific Rise and tested these hypotheses by examining the effect of mercuric mercury [Hg(II)] on vent bacteria. Four of six moderate thermophiles, most of which were vent isolates belonging to the genus Alcanivorax, and six of eight mesophiles from the vent plume were resistant to >10 microM Hg(II) and reduced it to elemental mercury [Hg(0)].

Thermovibrio ammonificans sp. nov., a thermophilic, chemolithotrophic, nitrate-ammonifying bacterium from deep-sea hydrothermal vents.

A thermophilic, anaerobic, chemolithoautotrophic bacterium was isolated from the walls of an active deep-sea hydrothermal vent chimney on the East Pacific Rise at 9 degrees 50' N. Cells of the organism were Gram-negative, motile rods that were about 1.0 microm in length and 0.

Coupling of bacterial endosymbiont and host mitochondrial genomes in the hydrothermal vent clam Calyptogena magnifica.

The hydrothermal vent clam Calyptogena magnifica (Bivalvia: Vesicomyidae) depends for its nutrition on sulfur-oxidizing symbiotic bacteria housed in its gill tissues. This symbiont is transmitted vertically between generations via the clam's eggs; however, it remains uncertain whether occasionally symbionts are horizontally transmitted or acquired from the environment. If symbionts are transmitted strictly vertically through the egg cytoplasm, inheritance of symbiont lineages should behave as if coupled to the host's maternally inherited mitochondrial DNA.