Xenobiotics are foreign substances, synthetic and unnatural chemicals such as pesticides, solvents, herbicides, refrigerants and other organic compounds. These substances remain in the atmosphere for number of years and cause environmental degradation and ultimately affect the human beings by entering the food chain. This is known as Bioaccumulation.
Microbes transform the complex organic substances into relatively simpler non-toxic substances. This process is called as Biodegradation. The use of microorganisms to remove the environmental pollutants i.e. the toxic chemicals found in water, soil and air is called Bioremediation.
Sometimes, more than one strain of microbes is employed to degrade a single compound. There are several enzyme systems present in microbes for the degradation of chemicals. The genes encoding for the enzymes of the biodegradative pathway maybe present on the chromosomal DNA or more so on the plasmids.
Given below is a list of microbes used in the environmental degradation of chemicals:
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Name of Microbe
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Pollutant chemical degraded
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1.
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Pseudomonas
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Hydrocarbons including Benzene, xylene, toluene, organophosphates, Polychlorinated Biphenys (PCB’s )
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2.
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Streptomyces
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Halogenated hydrocarbons, phenoxyacetate
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3.
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Aspergillus
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Phenolic compounds
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4.
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Candida
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Polychlorinated Biphenlys (PCB’s )
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5.
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Xanthomonas
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Polycyclic hydrocarbons
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