Bioremediation of PCB & Pesticide Contaminated Soils Utilizing Gene Expression Factors

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 Abstract

Historically soils contaminated by persistent organic compounds such as pesticides and PCBs were not considered good candidates for bioremediation due to the simple fact that the chemical industry designed these compounds to withstand the destructive effects of natural attenuation through weathering and microbial activity. Although the chemical industry has long appreciated the benefits of persistence afforded by chlorinating a chemical product, the industry failed to appreciate the long-term environmental and potential human health consequences of producing millions of tons of toxic materials that were essentially immune to natural breakdown. Today PCBs and pesticides are ubiquitous in the environment and while there is little qualified dispute as to the harmful effects of these toxins, there is also a growing body of scientific and medical research that point to a causal relationship between these persistent toxins and human disease.

Early in 1992, Dr. Ellis L. Kline expanded his research in microbiology to include genetic studies of indigenous soil microorganisms. In his study of soils contaminated by PCBs and pesticides, Dr. Kline found that viable populations of soil microorganisms are able to survive in contaminated soil but that the organisms are incapable of biologically degrading the pollutants. Additional studies revealed that the presence of chlorinated compounds in the soil has the effect of inhibiting or repressing the microbial genes responsible for enzyme production. As an essential element in the biological reduction of organics for mineralization and reproduction, it became clear that it is the inability of soil microorganisms to produce reductive enzymes that permit PCBs and pesticides to resist biological breakdown.

For the first time, the physiological mechanisms of designed persistence were becoming known. With this knowledge Dr. Kline and his research team launched a focused effort to develop a method by which chemically repressed genes could be de-repressed thereby promoting microbial enzyme production and the destruction of the target pollutant. In 1994, the research team succeeded in developing the first Microbial Gene Expression Factor designed to negate chemically induced gene repression and to promote rapid microbial destruction of persistent organic chemicals in treated soils.

This report provides a brief synopsis of four laboratory bench scale and field studies that illustrate the effectiveness of FACTOR TREATMENTS in biologically reducing and eliminating PCBs and pesticides. In addition to the effectiveness of the treatments, the principals of RTE believe that the economics of Factor Treatments will motivate owners of contaminated sites to take a pro-active position relative to site remediation. Initial modeling suggests potential savings of up to 75% over conventional disposal methods.

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