The sulfate-reducing bacterium Desulfovibrio desulfuricans ND132 as a model for understanding bacterial mercury methylation
- Smithsonian Environmental Research Center, Edgewater, MD
- ORNL
- University of Missouri, Columbia
- University of Missouri
We propose the use of Desulfovibrio desulfuricans ND132 as a model species for understanding the mechanism of microbial Hg methylation. Strain ND132 is an anaerobic dissimilatory sulfate-reducing bacterium (DSRB), isolated from estuarine mid-Chesapeake Bay sediments. It was chosen for study because of its exceptionally high rates of Hg methylation in culture and its metabolic similarity to the lost strain D. desulfuricans LS, the only organism for which methylation pathways have been partially defined. Strain ND132 is an incomplete oxidizer of short-chain fatty acids. It is capable of respiratory growth using fumarate as an electron acceptor, supporting growth without sulfide production. We used enriched stable Hg isotopes to show that ND132 simultaneously produces and degrades methylmercury (MeHg) during growth but does not produce elemental Hg. MeHg produced by cells is mainly excreted, and no MeHg is produced in spent medium. Mass balances for Hg and MeHg during the growth of cultures, including the distribution between filterable and particulate phases, illustrate how medium chemistry and growth phase dramatically affect Hg solubility and availability for methylation. The available information on Hg methylation among strains in the genus Desulfovibrio is summarized, and we present methylation rates for several previously untested species. About 50% of Desulfovibrio strains tested to date have the ability to produce MeHg. Importantly, the ability to produce MeHg is constitutive and does not confer Hg resistance. A 16S rRNA-based alignment of the genus Desulfovibrio allows the very preliminary assessment that there may be some evolutionary basis for the ability to produce MeHg within this genus.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- DE-AC05-00OR22725
- OSTI ID:
- 1018977
- Journal Information:
- Applied and Environmental Microbiology, Vol. 77, Issue 12; ISSN 0099--2240
- Country of Publication:
- United States
- Language:
- English
Similar Records
Bacterial Growth Phase Influences Methylmercury Production by the Sulfate-Reducing Bacterium Desulfovibrio desulfuricans ND132
Bacterial Growth Phase Influences Methylmercury Production by the Sulfate-Reducing Bacterium Desulfovibrio desulfuricans ND132
Related Subjects
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
AVAILABILITY
BINDING ENERGY
CARBOXYLIC ACIDS
CHEMISTRY
DESULFOVIBRIO
DISTRIBUTION
ELECTRONS
MASS BALANCE
MERCURY
METHYLATION
METHYLMERCURY
OXIDIZERS
PARTICULATES
PRODUCTION
SEDIMENTS
SOLUBILITY
STRAINS
SULFIDES
VALENCE
Mercury
Hg
SFA