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-t ransferase genes from Escherichia coli and Schistosoma mansoni, respectivel y. This method enabled strains containing simultaneously mer and glutathion e S-transferase genes to grow in high concentrations of mercuric chloride ( 30 mu g/ml) and to volatilize part of the mercury (248 mu g/g cell dry wt.) present in the culture medium, while strains bearing only a single gene, d id 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 prelim inary, the genetically engineered strain containing simultaneously the mel and glutathione S-transferase genes show a great potential for bioremediati on. It may be used in a closed system to remove by volatilization, and reco ver mercury (Hg-0) from contaminated effluents, such as industrial effluent , for instance. (C) 2000 Published by Elsevier Science B.V. All rights rese rved.