aromatica strain RCB is the only organism in pure culture that can oxidize
benzene in the absence of oxygen (5). It can also oxidize aromatics such
as toluene, benzoate, and chlorobenzoate. D. aromatica couples growth
and benzene oxidation to the reduction of either O2, chlorate, or nitrate
(5). Benzene is completely mineralized to CO2. Benzene contamination is
a significant problem worldwide. It is widely used in various manufacturing
processes and is also a primary component of petroleum-based fuels. Benzene
is a highly soluble, mobile, toxic, and stable hydrocarbon especially in
ground and surface waters. It is poorly biodegraded in the absence of oxygen.
The pathway of benzene degradation in D. aromatica is unknown, however,
preliminary studies suggest that it has both a diooxygenase-based aerobic
pathway and an as yet uncharacterized anaerobic pathway (5) (J.D. Coates,
unpublished). The dioxygenase-based pathway is used by the organism when
growing with O2 or chlorate as the electron acceptor. With chlorate as the
electron acceptor, the oxygen required by the dioxygenase is supplied as
a result of chlorite dismutation (J.D. Coates, unpublished). When anoxic
aquatic sediments containing [14C]-labeled benzene were inoculated with
D. aromatica, the benzene was rapidly oxidized to CO2 (R. Chakraborty,
unpublished). These results demonstrate the applicability of D. aromatica
to the engineered attenuation of benzene in-situ.
summary, the Dechloromonas represents a unique genus with a broad
range of novel metabolic capabilities and bioremediative applicability.
Although this genus was only recently described (1), there are now several
members in pure culture (1, 8). In addition, screening studies of a broad
diversity of environments utilizing specific molecular probes (7) (L.A.
Achenbach, unpublished) have demonstrated the ubiquity of this group of
organisms. Although the role of Dechloromonas species in the environment
has yet to be determined, as our studies indicate these organisms have
a diverse range of metabolic capabilities to exploit. These unique metabolic
capabilities foretell the likelihood of a significant number of novel
genes, thus expanding the database for genomic and proteomic studies.
Sequencing of the D. aromatica genome will greatly enhance our
understanding of this unique group of organisms and thereby increase their
applicability to bioremediation and biotechnology.
- Achenbach, L. A.,
R. A. Bruce, U. Michaelidou and J. D. Coates. 2000. Dechloromonas
agitata N.N. gen., sp. nov. and Dechlorosoma suillum N.N.
gen., sp. nov. two novel environmentally dominant (per)chlorate-reducing
bacteria and their phylogenetic position. Int J. of Syst. Bact. 51:
- Achenbach, L. A.
and J. D. Coates. 2000. Disparity between bacterial phylogeny and physiology.
ASM News 66: 714-716
- Bruce, R.A., Achenbach,
L.A., Coates, J.D. (1999). Reduction of (per)chlorate by a novel organism
isolated from a paper mill waste. Environ Microbiol 1:319-331.
- Chaudhuri, S. Lack,
J.G. and Coates, J.D. (2001). Biogenic magnetite formation through anaerobic
biooxidation of Fe(II). Applied and Environmental Microbiology 67:2844-2848.
- Coates, J.D., Chakraborty,
R., Lack, J.G., OConnor, S.M., Cole, K.A., Bender, K.S., and Achenbach,
L.A. (2001) Anaerobic benzene oxidation coupled to nitrate reduction
in pure culture by two novel organism. Nature 411: 1039-1043.
- Coates, J. D.,
R. A. Bruce and J. D. Haddock. 1998. Anoxic bioremediation of hydrocarbons.
- Coates, J. D.,
R. A. Bruce, J. A. Patrick and L. A. Achenbach. 1999. Hydrocarbon bioremediative
potential of (per)chlorate-reducing bacteria. Bioremed J 3:323-334.
- Coates, J. D.,
U. Michaelidou, R. A. Bruce, S. M. O'Connor, J. N. Crespi and L. A.
Achenbach. 1999. The ubiquity and diversity of dissimilatory (per)chlorate-reducing
bacteria. Appl Environ Microbiol 65:5234-5241.
- Goldberg, S. 1989.
Interaction of aluminum and iron oxides and clay minerals and their
effect on soil physical properties: A review. Commun. in Soil Sci. Plant
- Lack, J. G., S.
K. Chadhuri and J. D. Coates. 2000. Radionuclide immobilization mediated
by anaerobic biooxidation of Fe(II). Appl Environ Microbiol. (in press)
- Michaelidou, U.,
Achenbach, L.A., and Coates, J.D. (2000). Isolation and characterization
of two novel (per)chlorate-reducing bacteria from swine waste lagoons.
In Perchlorate in the Environment (E. Urbansky, ed)
- Ryan, J. N. and
P. M. Gschwend. 1990. Colloid mobilization in two Atlantic coastal plain
aquifers: field studies. Wat. Resour. Res. 26:307-322.
- Stucki, J. W.,
P. Komadel and H. T. Wilkinson. 1987. Microbial reduction of structural
iron (III) in smectites. Soil Sci. Soc. Am. J. 51:1663-1665.
- van Ginkel, C.,
G. Rikken, A. Kroon and S. Kengen. 1996. Purification and characterization
of chlorite dismutase: a novel oxygen-generating enzyme. Arch. Microbiol.
- Wu, J., C. B. Roth
and P. F. Low. 1988. Biological reduction of structural iron in sodium-nontronite.
Soil Sci. Soc. Am. J. 52:295-296.