Mercury and other heavy metals influence bacterial community structure in low-order Tennessee streams
- ORNL
High concentrations of the heavy metals U(VI) and Hg(II) as well as inorganic compounds including nitrate have contaminated streams located in the Department of Energy reservation in Oak Ridge, TN. Of particular concern is methylmercury (MeHg) as it is more neurotoxic than Hg0. Deltaproteobacteria including sulfate reducing bacteria (SRB) and iron reducing bacteria (IRB) have been generally identified as the primary methylators. In order to determine potential effects on microbial community composition by the contamination, surface stream sediments were collected 7 times during the year from 5 contaminated sites and 1 control site. Sixty samples were analyzed for bacterial community composition and geochemistry. Community characterization used GS 454 FLX pyrosequencing with 235 Mb of 16S rDNA sequence targeting the V4 region. Sorting and filtering of the raw reads resulted in 588,699 high quality sequences with lengths of >200 bp. The bacterial community was represented by 24 phyla and unclassified Bacteria including Proteobacteria (22.9-58.5%), Cyanobacteria (0.2-32.0%), Acidobacteria (1.6-30.6%), and Verrucomicrobia (3.4-31.0%). Redundancy analysis indicated there were no significant differences in the bacterial community structure between midchannel and near bank samples. However, significant correlations existed between the bacterial community and seasonal as well as geochemical variation. Further, several members of the community appear to be positively associated with MeHg including the Proteobacteria group that includes SRBs as well as Verrucomicrobia. This study is the first to indicate the influence of MeHg on an in-situ microbial community and suggests possible roles for each of these phyla in the Hg/MeHg cycle.
- 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:
- 1081649
- Journal Information:
- The ISME Journal: Multidisciplinary Journal of Microbial Ecology, Vol. 77, Issue 1
- Country of Publication:
- United States
- Language:
- English
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