Bioremediation of polyaromatic hydrocarbons

Intrinsic remediation depends on natural processes such as biodegradation by indigenous microorganisms, dispersion, volatilization and adsorption to remove contaminants in soil and groundwater. Biodegradation is the most important process, in the natural attenuation of many contaminants such as petroleum hydrocarbons. It is generally accepted that contaminated areas rapidly become anoxic and, of the terminal electron acceptors, which can be used under these conditions, Fe(III) is the most abundant in soils. Fe(III) presents a challenge as it is extremely water insoluble and may not be bioavailable in soils and groundwater but indirect geochemical evidence indicates the substantial Fe(III) reduction does occur. We are attempting to elucidate the mechanism(s) by which microbes may access Fe(III) as a terminal electron acceptor in hydrocarbon degradation. This may involve the use of siderophores, electron shuttling agents, direct contact of the microorganisms with the insoluble Fe(III) or a combination of the three. A longer-term goal is to develop a gene probe to determine the presence of these Fe(III)-reducing microorganisms in the environment.

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