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Thiomicrospira denitrificans ATCC 33889 has
been reclassified as Sulfurimonas denitrificans DSM 1251 (ATCC 33889) on 11/7/2007.
Chemoautotrophy
Chemoautotrophs grow by powering CO2 fixation with the energy
released by the oxidation of a smorgasbord of redox substrates. Electron
donors utilized by these organisms include reduced sulfur (H2S,
S2O3-2, S°, etc.), reduced iron (e.g.,
Fe+2, pyrite), reduced nitrogen (NH3, NO2-)
and H2 (Kuenen and Bos, 1989), while O2, NO3-,
SO4-2, and Fe+3 can serve as electron
acceptors (Kelly and Wood, 2001). By coupling the oxidation and reduction
of inorganic compounds to the generation of biomass, the activities of
these organisms tie the geochemical cycle of their redox substrates to
the carbon, nitrogen, and phosphorus cycles. Further, at H2S,
Fe+2, and H2-rich deep-sea hydrothermal vents and
cold seeps, free-living and symbiotic sulfur-oxidizing chemoautotrophs
are dominant primary producers (Jannasch, 1979).
Sulfur oxidation
The bacteria of the oxidative part of the sulfur cycle are of global importance
and catalyze complex pathways for the complete oxidation of sulfide to
sulfate. One of the important groups catalyzing the oxidation of reduced
sulfur compounds in the marine environment are bacteria belonging to the
genus Thiomicrospira, a group which originally included all marine,
spiral-shaped sulfur oxidizing bacteria. Subsequent analyses of 16S rDNA
sequences have revealed the polyphyletic nature of this group; members
of Thiomicrospira are distributed among the gamma and epsilon
subdivisions of the Proteobacteria. All Thiomicrospira species
characterized to date are obligate chemolithoautotrophic bacteria that
use sulfide, thiosulfate, and elemental sulfur as electron donors, and
CO2 as their carbon source. Two organisms (gamma and epsilon-Proteobacteria)
have been selected to embrace the phylogenetic breadth of proteobacterial
chemoautotrophs.
Thiomicrospira denitrificans
T. denitrificans, which is in the epsilon subdivision of Proteobacteria,
was originally isolated from the Dutch Wadden Sea (Timmer-Ten Hoor, 1975).
As with T. crunogena, 16S rRNA surveys have identified sequences closely
related to T. denitrificans from several hydrothermal habitats
(e.g. Reysenbach et al., 2000; Huber et al., 2003), indicating that these
organisms might play an important role in these environments. In addition,
isolates closely related to T. denitrificans that are also able
to oxidize sulfide with nitrate have been obtained from oilfields, where
they play an important role in anaerobically oxidizing sulfide produced
by sulfate-reducing bacteria (e.g., Watanabe et al., 2000).
References
Brinkhoff, T., Sievert, S.M., Kuever, J., and Muyzer, G. (1999) Distribution
and diversity of sulfur-oxidizing Thiomicrospira spp. at a shallow-water
hydrothermal vent in the Aegean Sea (Milos, Greece). Appl. Environ. Microbiol.
65: 3843-3849.
Huber, J., Butterfield, D.A., and Baross, J.A. (2003) Bacterial diversity
in a subseafloor habitat following a deep-sea volcanic eruption. FEMS Microbiol.
Ecol. 43: 393-409.
Jannasch HW, Wirsen CO (1979) Chemosynthetic primary production at East
Pacific sea floor spreading centers. BioSci. 29: 592-598
Jannasch, H., Wirsen, C., Nelson, D., and Robertson, L. (1985) Thiomicrospira
crunogena sp. nov., a colorless, sulfur-oxidizing bacterium from a
deep-sea hydrothermal vent. Int. J. Syst. Bacteriol. 35: 422-424.
Kelly, D.P., and Wood, A.P. (2001). The chemolithotrophic prokaryotes.
URL http://80-link.springer-ny.com.ezp2.harvard.edu/link/service/books/10125/
Kuenen, J.G., and Bos, P. (1989) Habitats and ecological niches of chemolitho(auto)trophic
bacteria. In Autotrophic Bacteria. Schlegel, H.G., and Bowien, B. (eds).
Madison: Springer-Verlag, pp. 117-146.
Muyzer, G., Teske, A., Wirsen, C., and Jannasch, H. (1995) Phylogenetic
relationships of Thiomicrospira species and their identification
in deep-sea hydrothermal vent samples by denaturing gradient gel electrophoresis
of 16S rDNA fragments. Archives of Microbiology 164: 165-172.
Reysenbach, A.-L., Longnecker, K., and Kirshtein, J. (2000) Novel bacterial
and archaeal lineages from an in situ growth chamber deployed at a Mid-Atlantic
Ridge hydrothermal vent. Appl. Environ. Microbiol. 66: 3798-3806.
Timmer-Ten Hoor, A. (1975) A new type of thiosulphate oxidizing, nitrate
reducing microorganism: Thiomicrospira denitrificans sp. nov.
Netherland Journal of Sea Research 9: 344-350.
Watanabe, K., Watanabe, K., Kodama, Y., Syutsubo, K., and Harayama, S.
(2000) Molecular characterization of bacterial populations in petroleum-contaminated
groundwater discharged from underground crude oil storage cavities. Appl
Environ Microbiol 66: 4803-4809.
Wirsen, C.O., Brinkhoff, T., Kuever, J., Muyzer, G., Jannasch, H.W., and
Molyneaux, S.J. (1998) Comparison of a new Thiomicrospira strain
from the mid-atlantic ridge with known hydrothermal vent isolates. Applied
and Environmental Microbiology 64: 4057-4059.
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