Coal fired electric plant mercury pollution and lax enforcement of EPA rulings have left most Alabama waterways with a high level of mercury.
The Alabama Department of Public Health 2010 Fish Consumption Advisories states
“Beginning with the 2007 advisories, ADPH adopted a contaminant level for mercury in fish that would protect those who might consider eating more than one fish meal per week. The new U.S. Environmental Protection Agency (EPA) standards are four times more protective than Food and Drug Administration (FDA) levels previously used. After the lower, more protective limit was adopted in 2007, an increasing number of waterbodies around the state received advisories for mercury in fish as they were tested. Newly issued advisories will be represented as the safe number of meals of that species of fish that can be eaten in a given period of time, such as meals per week, meals per month or no consumption. A meal portion consists of 6 ounces of cooked fish or 8 ounces of raw fish.”
Research published at the Public Library of Science on March 14, 2011, details the genetic modification of one species of bacteria to produce a super mercury consuming species that is designed for bioremediation of mercury contaminated waters.
There is no way that Alabama government will abide by the Clean Air and Water Act as long as Alabama Power funds the politicians campaigns so maybe the state could pop for some bacteria to clean up the mess.
Characterization of the Metabolically Modified Heavy Metal-Resistant Cupriavidus metallidurans Strain MSR33 Generated for Mercury Bioremediation
Luis A. Rojas 1,2
Carolina Yáñez 1, Myriam González 1, Soledad Lobos 2, Kornelia Smalla 3, Michael Seeger 1*
1 Laboratorio de Microbiología Molecular y Biotecnología Ambiental, Departamento de Química and Center for Nanotechnology and Systems Biology, Universidad Técnica Federico Santa María, Valparaíso, Chile
2 Laboratorio de Espectroscopía, Facultad de Farmacia, Universidad de Valparaíso, Playa Ancha, Valparaíso, Chile
3 Julius Kühn-Institut, Federal Research Centre for Cultivated Plants (JKI), Institute for Epidemiology and Pathogen Diagnostics, Braunschweig, Germany
Mercury-polluted environments are often contaminated with other heavy metals. Therefore, bacteria with resistance to several heavy metals may be useful for bioremediation. Cupriavidus metallidurans CH34 is a model heavy metal-resistant bacterium, but possesses a low resistance to mercury compounds.
To improve inorganic and organic mercury resistance of strain CH34, the IncP-1β plasmid pTP6 that provides novel merB, merG genes and additional other mer genes was introduced into the bacterium by biparental mating. The transconjugant Cupriavidus metallidurans strain MSR33 was genetically and biochemically characterized. Strain MSR33 maintained stably the plasmid pTP6 over 70 generations under non-selective conditions. The organomercurial lyase protein MerB and the mercuric reductase MerA of strain MSR33 were synthesized in presence of Hg2+. The minimum inhibitory concentrations (mM) for strain MSR33 were: Hg2+, 0.12 and CH3Hg+, 0.08. The addition of Hg2+ (0.04 mM) at exponential phase had not an effect on the growth rate of strain MSR33. In contrast, after Hg2+ addition at exponential phase the parental strain CH34 showed an immediate cessation of cell growth. During exposure to Hg2+ no effects in the morphology of MSR33 cells were observed, whereas CH34 cells exposed to Hg2+ showed a fuzzy outer membrane. Bioremediation with strain MSR33 of two mercury-contaminated aqueous solutions was evaluated. Hg2+ (0.10 and 0.15 mM) was completely volatilized by strain MSR33 from the polluted waters in presence of thioglycolate (5 mM) after 2 h.
A broad-spectrum mercury-resistant strain MSR33 was generated by incorporation of plasmid pTP6 that was directly isolated from the environment into C. metallidurans CH34. Strain MSR33 is capable to remove mercury from polluted waters. This is the first study to use an IncP-1β plasmid directly isolated from the environment, to generate a novel and stable bacterial strain useful for mercury bioremediation.
Citation: Rojas LA, Yáñez C, González M, Lobos S, Smalla K, et al. (2011) Characterization of the Metabolically Modified Heavy Metal-Resistant Cupriavidus metallidurans Strain MSR33 Generated for Mercury Bioremediation. PLoS ONE 6(3): e17555. doi:10.1371/journal.pone.0017555