Rhizosphere Microbial Communities of Herbicide-Tolerant Plants As Potential Bioremedients of Soils Contaminated with Agrochemicals

Abstract

Plant roots influence the soil in which they grow in a variety of ways, making the soil more conducive for microbial growth and activity, as well as cometabolic reactions. Studies examining the fate of pesticides in plant-soil systems have revealed a marked decrease in persistence of these compounds. Additionally, similar observations have recently been made for oil residues, polycyclic aromatic hydrocarbons, trichloroethylene, and surfactants. These previous studies suggest that the root zone could potentially be managed to effect bioremediation of surface soils containing hazardous organic compounds through enhanced biochemical transformation of these organic constituents at waste sites by indigenous rhizosphere microorganisms. In order to further test this hypothesis, a study was initiated using soil and vegetation from an existing pesticide-contaminated site in Iowa. Initial characterization of this site revealed several herbicide-tolerant plant species including Kochia sp., knotweed (Polygonum sp.), and crabgrass (Digitaria sp.). Experiments testing the influence of these tolerant varieties on microbial degradation of a mixture of herbicides are reported. By facilitating microbial degradation of pesticide wastes, vegetation could provide a cost-effective and ecological approach to restoration of contaminated surface soils in situ.

Herbicides and Pesticides as Potential Pollutants: A Global Problem

“…Herbicide and pesticide contamination is usually too expensive to clean up with current mentioned technologies. Studies have shown that certain tolerant plants and microbes can be used in biological remediation which can be cost-effective and simpler, due to the in-situ advantage, pollution can be exacerbated by the pesticides/herbicides involved, but these, too can be remediated through biological remediation (Perkovich et al 1996;Kruger et al 1997;Anderson et al 1995). Most of the naturally occurring microorganisms are selected on conventional culture media which has many drawbacks for the selection.…”

The fate of methyl bromide, ethylene glycol, and propylene glycol in soil and surface water: influence of soil variables and vegetation on degradation and offsite movement

“…Accelerated mineralization of pesticides has also been found in the rhizosphere of plants from pesticidecontaminated sites. Anderson and co-workers [22,53] Wetland plants may also be utilized to remediate contaminated water and soil. Like terrestrial plants, aquatic macrophytes are capable of taking contaminants up in their tissues and enhancing biodegradation in the rhizosphere.…”