|MadSci Network: Environment & Ecology|
Amna – That is a tougher question than it sounds – especially since this isn’t really my field of expertise. There are a wide range of chemicals that you might want to break down using bioremediation and each one will have its own set degradation steps. Most bioremediation relies on microbes using the compound of interest as a carbon source. As a result, microbes use all of the enzymes that they would use to break down normal organic matter – basically any enzyme you can name that breaks a bond. Texts on the subject (see below) usually concern themselves with the degradation pathways and likely products. The enzymes involved in all of the steps aren’t even necessarily known. Usually the most important step is the one that causes a big reduction in the toxicity. This can be any of a wide range of reactions: hydrolysis, dehalogenation, ester cleavage, ether cleavage, deamination, methylation/demethylation, hydroxylation, nitro-reduction, nitrile to amide conversion or conjugation.
Here are some enzymes associated with the degradation or detoxification of a number of well known organic compounds:
Polychlorodibenzodioxins -- lignin peroxidases
Organophosphates -- carboxyesterase (Malathion), Parathionhydrolase (Diazinon), phosphotriesterase
Aromatic hydrocarbons (some) -- catechol 1,2 dioxygenase
DDT -- dehydrodechlorinase
Methylbenzimidazol 2-yl carbamate -- MBC hydroxylate
The enzymes used in waste water treatment would be exactly the same for the organics. Many waste water plants add carbon to anoxic water to encourage bacteria to use nitrate reductase to convert NO3- to N2 gas.
I would check out the EPA’s site cleanup site: http://www.clu-in.org/
I hope this helps.
Bioremediation : science and applications by H.D. Skipper and R.F. Turco (1995) Madison, Wis. : Soil Science Society of America.
Biodegradation and Bioremediation by M.Alexander (1999) San Diego : Academic Press
Van Eerd, L. L., R. E. Hoagland, et al. (2003). “Pesticide metabolism in plants and microorganisms.” Weed Science 51(4): 472-495.
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