Researchers have shown that a genetically modified (GM) tobacco plant successfully transforms levels of 2,4,6-trinitrotoluene (TNT) found in contaminated soil. Neil Bruce and colleagues at the University of Cambridge and the Defence Science and Technology Laboratory at Fort Halstead in the United Kingdom report that transgenic tobacco seedlings growing in a 0.25 millimolar solution of TNT gained 18% in wet biomass weight over seven days, while wild-type plants lost 34% weight. Moreover, no TNT was extracted from the transgenic seedlings, indicating that the explosive was completely transformed or stored as an inextractable form in the plant.

Unexploded TNT in soil poses a safety hazard and a serious toxic environmental threat to groundwater and soil health. Incineration, the current best remediation procedure, can lead to other environmental problems, such as air pollution from incomplete combustion. Thus, a phytoremediation approach that can fully transform TNT significantly reduces the safety and environmental problems in cleaning up this contaminant.

To modify tobacco to handle TNT, the scientists introduced a gene encoding for a nitroreductase enzyme that converts TNT to aminonitrotoluene compounds, which can then undergo further reactions. The nitroreductase gene, known as nsfI, was taken from the bacteria Enterobacter cloacae. (Nat. Biotechnol. 2001, 19, 1168–1172) —RACHEL PETKEWICH