Elimination of mercury and organomercurials by nitrogen-fixing bacteria
- Univ. of College of Science, Calcutta (India); and others
Bacteria isolated from mercury-polluted environments are often resistant to mercuric ions (Hg{sup 2+}) and organomercurials. Plasmids determining mercury resistance have been well characterized in gram-negative system. However, in Staphylococcus aureus mercury resistance has been found to be chromosomally determined. The known mechanism of bacterial Hg{sup 2+}-resistance is detoxification of the toxic Hg{sup 2+} by its enzymatic transformation by mercuric reductase to Hg (o). Organomercurial lyase mediates the degradation of organomercurial compounds to Hg{sup 2+}. Mercury and organomercurial resistances have been studied in different bacterial genera. There is little information on Hg-resistance in N{sub 2}-fixing soil bacteria, however, in many developing countries, including India, mercury pollution is still a problem because Hg-based pesticides and fungicides are still used routinely as seed-dressers in agriculture to control soil-borne and seed-borne fungal diseases. Volatilization of Hg from laboratory media by mercury-resistant bacteria containing low levels of mercury has been reported by several workers. It is interesting to note that N{sub 2}-fixing, Hg-resistant soil isolates could volatilize Hg from medium containing very high amounts of HgCl{sub 2}. In the present paper we report the volatilization patterns of five N{sub 2}-fixing bacterial strains, the effect of different inducers on mercuric reductase, and the pattern of substrate utilization by organomercurial lyase. In the presence of a low concentration of HgCl{sub 2}. enzymatic detoxification is sufficient to combat the adverse situation created by the presence of Hg{sup 2+} ions. In the presence of a high concentration of HgCl{sub 2}, intracellular sequestration by Hg{sup 2+} binding components may play an additional role in counteracting Hg-toxicity.
- OSTI ID:
- 530480
- Journal Information:
- Bulletin of Environmental Contamination and Toxicology, Journal Name: Bulletin of Environmental Contamination and Toxicology Journal Issue: 6 Vol. 58; ISSN 0007-4861; ISSN BECTA6
- Country of Publication:
- United States
- Language:
- English
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