An Enzyme to Protect Waterways from the Herbicide, Atrazine
Farmers around the world depend on herbicides as part of efficient and economic primary production. One of the most highly effective groups of herbicides is the 1,3,5-triazines which includes the widely used atrazine. They have been used extensively to control broadleaf weeds since 1958. However, atrazine also has the potential to contaminate surface and groundwater even when used at the recommended levels. Because of this, triazine use in the sugar cane growing region of Australia and in the Great Barrier Reef catchment area has been identified as a threat to significant freshwater wetlands as well as marine ecosystems in the Great Barrier Reef World Heritage Area. There have been attempts to use bioremediation (the use of biological agents to clean up contaminants) to remove triazine herbicide residues from the environment which relied on the use of genetically modified organisms. One of the attempts involved the use of the bacterium, Escherichia coli, and another used transgenic rice, but neither approach is likely to go further because of the high level of regulation around the release of genetically modified organisms. Because of this, CSIRO Entomology scientists have been looking at an alternative, enzyme-based remediation approach, which does not involve the use of live organisms. A large scale field trial in the sugar growing areas of north Queensland has shown that an enzyme-based product developed by this group can remediate water bodies contaminated with atrazine. The CSIRO group looked for bacteria that 'feed' on atrazine, then identified the enzymes in the bacterium which reduced atrazine to non-active products. These were the enzymes that were potentially useful for atrazine bioremediation and the group then focussed on one enzyme that acts on a broad range of triazines. While the enzyme selected was perfectly suited to the bacterium's needs, it was not efficient enough to use as a bioremediation product, so the group modified it to one that was suitable for large scale use and mass production.
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Document Type: Research Article
Publication date: 2009-08-01
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