Methanotrophic-Mediated Methylmercury Transformation: Characterization of Products, Mechanism, and Environmental Significance (Final Technical Report)
Previous work in the laboratories of the PIs found that methanotrophs, through the production of a novel metal chelator called methanobactin (MB), can bind inorganic mercury (Hg[II]). By doing so, methanotrophs substantially reduce Hg[II] toxicity. We have also recently shown that MB can bind a much more toxic form of mercury, the neurotoxin methylmercury (MeHg). MeHg bioaccumulates and biomagnifies in biota such as fish, and is of significant concern. Further, certain methanotrophs expressing MB are able to demethylate significant amounts of MeHg despite lacking merB, the organomercurial lyase. Further, unlike the canonical organomercurial lyase, methanotrophs take up and degrade MeHg at environmentally relevant pH and Hg concentrations (i.e., picomolar to nanomolar), suggesting that methanotrophs likely play a critical role in controlling net MeHg production and toxicity in situ. However, although MB is necessary for methanotrophic-mediated MeHg degradation, it is not sufficient as purified MB binds, but does not degrade MeHg. That is, MB appears to serve as binding device leading to demethylation of MeHg by an as yet unknown mechanism. The major goals of this project were to extend this initial work and characterize the mechanism of methanotrophic-mediated MeHg demethylation and how methanobactin production may affect net methylmercury production in situ.
- Research Organization:
- Univ. of Michigan, Ann Arbor, MI (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER)
- Contributing Organization:
- Iowa State University
- DOE Contract Number:
- SC0018059
- OSTI ID:
- 1692379
- Report Number(s):
- DOE-MICHIGAN-0018059
- Country of Publication:
- United States
- Language:
- English
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