Capacity of mercury volatilization by mer (from Escherichia coli) and glutathione S-transferase (from Schistosoma mansoni) genes cloned in Escherichia coli

A study was carried out to evaluate the capacity for mercury volatilization by genetically engineered strains that express the mer and glutathione S-transferase genes from Escherichia coli and Schistosoma mansoni, respectively. This method enabled strains containing simultaneously mer and glutathione S-transferase genes to grow in high concentrations of mercuric chloride (30 μg/ml) and to volatilize part of the mercury (248 μg/g cell dry wt.) present in the culture medium, while strains bearing only a single gene, did not have the same behavior. Up to 70% of the total mercury of bacterial volatilization occurred in the first 4 h. Although the findings were preliminary, the genetically engineered strain containing simultaneously the mer and glutathione S-transferase genes show a great potential for bioremediation. It may be used in a closed system to remove by volatilization, and recover mercury (Hg 0) from contaminated effluents, such as industrial effluent, for instance.