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Scientists target microorganisms to break down toxic pesticide

17.01.2003

Using biological means to detoxify large, contaminated sites is receiving high praise as an alternative to incineration or landfill methods

A pesticide used extensively all over the world is receiving attention these days more for methods being used to clean it up than for its use as chemical to control insects and mites.

Endosulfan, classified as an organochlorine (the same family as DDT), is registered for use as a pesticide on 60 U.S. crops. Its residues have been found in the atmosphere, soils, sediments, surface and ground waters, and food. It is one of the most commonly detected pesticides in U.S. water (38 states) and is rated by the Environmental Protection Agency as a Category 1 pesticide with extremely high acute toxicity. Endosulfan affects the central nervous system, kidney, liver, blood chemistry and parathyroid gland and has reproductive, teratogenic and mutagenic effects.

Total average annual use of endosulfan is estimated at approximately 1.38 million pounds of the active ingredient. Endosulfan and its breakdown products are persistent in the environment with an estimated half-life of 9 months to 6 years. Because it is a persistent organic pollutant (POP) that enters the air, water, and soil during its use and manufacture, scientists have been researching ways to safely and effectively breakdown this neurotoxin.

Researchers from the University of California-Riverside and the University of Agriculture, Faisalabad, Pakistan, recently identified specific microorganisms which can breakdown the toxicity of endosulfan. Detoxifying pesticides through biological means is receiving serious attention as an alternative to existing methods, such as incineration and landfill, which are not sufficient for large, contaminated sites. By identifying microorganisms to specifically degrade endosulfan, these researchers were able to drastically reduce the toxic residues in the soil. The results of this study are published in the January-February issue of the Journal of Environmental Quality.

Various environmental samples were collected from different polluted sites to identify and isolate microorganisms for their ability to breakdown endosulfan. Out of 10 microorganisms isolated and screened, two proved successful in degrading endosulfan: Fusarium and Pandoraea spp.

Project leader William T. Frankenberger, University of California-Riverside, states, “Pollutants can be degraded by microorganisms when they use the toxin as a carbon and energy source. We have been successful in isolating two strains that have immense potential for endosulfan degradation.”

The results of this work suggest these novel strains are a valuable source of endosulfan-degrading enzymes and may be used for the detoxification of endosulfan in contaminated soils, wastedumps, water bodies, industrial effluents and unused or expired stockpiles of the pesticide.

The Journal of Environmental Quality, http://jeq.scijournals.org is a peer-reviewed, international journal of environmental quality in natural and agricultural ecosystems published six times a year by the American Society of Agronomy (ASA), Crop Science Society of America (CSSA), and the Soil Science Society of America (SSSA). The Journal of Environmental Quality covers various aspects of anthropogenic impacts on the environment, including terrestrial, atmospheric, and aquatic systems.

The American Society of Agronomy (ASA) www.agronomy.org, the Crop Science Society of America (CSSA) www.crops.org and the Soil Science Society of America (SSSA) www.soils.org are educational organizations helping their 10,000+ members advance the disciplines and practices of agronomy, crop, and soil sciences by supporting professional growth and science policy initiatives, and by providing quality, research-based publications and a variety of member services.