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Microbial adaptation to degradation of natural and synthetic organo halogens: Effects on ecosystem acclimation and natural bioremediation of polluted sites

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Enzymes remove pollutants from soil and groundwater

An ecological line of action for treating pollution is one that facilitates and enhances natural biodegradation of the polluting compounds. Intense bio-mediation is triggered by aerobic micro-organisms and microbial communities. Their presence catalyses and greatly accelerates chemical decompositions. The objective of the current research project has been to investigate and analyse the ways these micro-organisms adapt and degrade soil and water pollutants.


Novel organisms have been observed to possess the remarkable property of degrading recalcitrant halogenated environmental pollutants like chrolomethane, dibromoethane and dichloropropene. Biological clean-up methods, if well understood can and will offer substantial assistance in the international effort for a better and cleaner environment. Laboratory research conducted by a collaboration of environmental research institutes has shown that organisms producing dehalogenating enzymes detoxify samples of agricultural soil contaminated with 1,3 dichloropropene and 1,2 dichloroethane as an inoculum. The enzymes separate the carbon-chlorine and carbon-bromine bonds and in this way detoxify the pollutants. The results indicate that enzyme-producing organisms occur at higher frequencies in soils that have a history of pollution with halogenated compounds. These specific contaminants 1,3 dichloropropene and 1,2 dichloroethane were thought to be recalcitrant to biodegradation but now degradation pathways have been established and the dehalogenating enzymes involved in the process have been identified and characterised. Furthermore these novel organisms have the ability to even utilise natural or xenobiotic halocydrocarbons as a growth substrate. Research partners have also studied the halocarboxylic acid dehalogenases, a diverse class of enzymes that detoxify chlorinated compounds. Instead of using traditional methods of classification like activity profile and/or molecular weight, this time enzymes were classified according to a method that uses sequence comparisons. The microbial processes that are important for adaptation to synthetic compounds were also investigated. It has been demonstrated how these processes are influenced by environmental factors. Moreover, generic methods for stimulating indigenous microbial populations have also been developed. The insight gained into the molecular mechanisms that underlie the dehalogenation reactions and those which can be used for the development of molecular probes that will assess the degradation potential of contaminated sites. The current research has produced important results that will pave the way for better exploitation of natural biodegradation processes.

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