Molecular Mechanisms of Bacterial Mercury Transformation

Summers, Anne O.¹  Smith, Jeremy C.² 

[1]Univ. of Georgia, Athens, GA (United States). Dept. of Microbiology

[2]Univ. of Tennessee, Knoxville, TN (United States). Dept. of Biochemistry and Cellular and Molecular Biology

关键词: mercury;    methylmercury;    mercury resistance;    metallobiology;   

DOI  :  10.2172/1248536
RP-ID  :  DOE-UGA--395
PID  :  OSTI ID: 1248536

学科分类：生物科学（综合）

美国|英语

来源: SciTech Connect

【 摘 要 】

Hg is of special interest to DOE due to past intensive use in manufacture of nuclear weapons at the Oak Ridge Reservation (ORR). Because of its facile oxidation/reduction [Hg(II)/Hg(0)] chemistry, ability to bond to carbon [as in highly toxic methylmercury: MeHg(I)] and its unique physical properties [e.g., volatility of Hg(0)], Hg has a complex environmental cycle involving soils, sediments, waterways and the atmosphere and including biotic and abiotic chemical and physical transport and transformations. Understanding such processes well enough to design stewardship plans that minimize negative impacts in diverse ecological settings requires rich knowledge of the contributing abiotic and biotic processes. Prokaryotes are major players in the global Hg cycle. Facultative and anaerobic bacteria can form MeHg(I) with consequent intoxication of wildlife and humans. Sustainable stewardship of Hg-contaminated sites requires eliminating not only MeHg(I) but also the Hg(II) substrate for methylation. Fortunately, a variety of mercury resistant (HgR) aerobic and facultative bacteria and archaea can do both things. Prokaryotes harboring narrow or broad Hg resistance (mer) loci detoxify Hg(II) or RHg(I), respectively, to relatively inert, less toxic, volatile Hg(0). HgR microbes are enriched in highly contaminated sites and extensive field data show they depress levels of MeHg >500-fold in such zones. So, enhancing the natural capacity of indigenous HgR microbes to remove Hg(II) and RHg(I) from soils, sediments and waterways is a logical component of a comprehensive plan for clean up and stewardship of contaminated sites.