, Volume 26, Issue 6, pp 1023–1031 | Cite as

The impact of ionic mercury on antioxidant defenses in two mercury-sensitive anaerobic bacteria



While the toxicological effects of mercury (Hg) are well studied in mammals, little is known about the mechanisms of toxicity to bacterial cells lacking an Hg resistance (mer) operon. We determined that Shewanella oneidensis MR-1 is more sensitive to ionic mercury [Hg(II)] under aerobic conditions than in fumarate reducing conditions, with minimum inhibitory concentrations of 0.25 and 2 μM respectively. This increased sensitivity in aerobic conditions is not due to increased import, as more Hg is associated with cellular material in fumarate reducing conditions than in aerobic conditions. In fumarate reducing conditions, glutathione may provide protection, as glutathione levels decrease in a dose-dependent manner, but this does not occur in aerobic conditions. Hg(II) does not change the redox state of thioredoxin in MR1 in either fumarate reducing conditions or aerobic conditions, although thioredoxin is oxidized in Geobacter sulfurreducens PCA in response to Hg(II) treatment. However, treatment with 0.5 μM Hg(II) increases lipid peroxidation in aerobic conditions but not in fumarate reducing conditions in MR-1. We conclude that the enhanced sensitivity of MR-1 to Hg(II) in aerobic conditions is not due to differences in intracellular responses, but due to damage at the cell envelope.


Shewanella oneidensis Geobacter sulfurreducens Mercury Glutathione Antioxidant Lipid peroxidation Thioredoxin 

Supplementary material

10534_2013_9679_MOESM1_ESM.ppt (150 kb)
Supplementary Fig. 1Growth of MR-1 under aerobic conditions (a) or fumarate reducing conditions (b) in the presence of Hg(II). Thick line 0 Hg(II); open circles 0.1 μM Hg(II); open triangles 0.25 μM Hg(II); open squares 0.5 μM Hg(II); open diamonds 1 μM Hg(II); filled triangles 2 μM Hg(II); filled circles 5 μM Hg(II). Symbols represent the mean of triplicate cultures. Error bars represent standard deviation of the mean (PPT 146 kb)
10534_2013_9679_MOESM2_ESM.ppt (92 kb)
Supplementary Fig. 2Growth of PCA in the presence of Hg(II). Thick line 0 Hg(II); open circles 0.5 μM Hg(II); open squares 1.0 μM Hg(II); open triangles 5.0 μM Hg(II); closed squares 10 μM Hg(II); closed circles 25 μM Hg(II). Symbols represent the mean of triplicate cultures. Error bars represent standard deviation of the mean (PPT 89 kb)


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Copyright information

© Springer Science+Business Media New York 2013

Authors and Affiliations

  • Yingjiao Wang
    • 1
  • Tyler Robison
    • 1
  • Heather Wiatrowski
    • 1
  1. 1.Department of BiologyClark UniversityWorcesterUSA

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