Petroleum hydrocarbons enzymes

Organic contaminants such as petroleum hydrocarbons or chlorinated solvents can be directly metabolized by proteins and enzymes, leading to the degradation, metabolism, or mineralization of the contaminants. Furthermore, many of these contaminants can be broken down into harmless products or converted into a source of food and energy for the plants or soil organisms.50... 

Bio-Spin is an ex situ, bioremediation technology that treats soils contaminated with petroleum hydrocarbons. According to the vendor, the Bio-Spin system first screens and separates oversized debris. Then the system adds enzymes, uses rotation to mix the enzymes and contaminated soil, and then discharges the treated soil into a stockpile. The treated soil is kept separate from surrounding soils until bioremediation is complete. 

Provides extracellular enzymes that initiate the breakdown of petroleum hydrocarbons, enhancing bioremediation. 

Long-term exposure of microbial populations to certain toxicants often is necessary for adaptation of enzymatic systems capable of degrading those toxicants. This was the case with the Exxon Valdez oil spill in Alaska in 1989. Natural microbial populations in Prince William Sound, Alaska, had developed enzyme systems that oxidize petroleum hydrocarbons because of long-term exposure to natural oil seeps and to hydrocarbons that leached from the pine forests in the area. Growth of these natural microbial populations was nutrient limited during the summer. Thus the application of nutrient formulations to the rocky beaches of Prince William Sound stimulated microbial growth and helped to degrade the spilled oil. 

Studies have been carried out on a number of animals, particularly species of crab, lobster and zooplankton, and on the in vivo metabolism of a wide range of xenobiotics. Cytochrome P-450 and the MFO system, and to a lesser extent glutathione S-transferase, have been characterized most. Much less is known of other enzymes and of mechanisms of xenobiotic activation and toxicity. Aspects reviewed include cytochrome P-450 monooxygenases (Bend et al. 1981 James 1989b), and petroleum hydrocarbon metabolism in marine plankton (Corner 1978). 

Lee RF, Singer SC (1980) Detoxifying enzymes system in marine polychaetes increases in activity after exposure to aromatic hydrocarbons. In McIntyre AD, Pearce JB (eds) Biological effects of marine pollution and the problems of monitoring. Rapp P V Reun Cons Int Explor Mer 179 29-32 Lee RF, Sauerheber R, Benson AA (1972) Petroleum hydrocarbons uptake and discharge by the marine mussel Mytilus edulis. Science 177 344-346... 

The MFO system is also known as the aryl hydrocarbon hydroxylase (AHH) or drug-metabolizing system in mammals. In fish, as in mammals, most MFO activity is localized in the liver (2.404 /imoles of B[a]P hydroxylase = AHH) and in minor amounts in kidney (0.026) and heart (0.006) (Pederson etaL, 1974). Many studies have shown the presence of various oxygenases in fish (Bend etal, 1977 Stegeman, 1978). AHH is present in many marine fish species from different habitats and life stories (Payne, 1977). Several fish species including rainbow trout can hydroxylate benzo[a]pyrene and naphthalene. Quantitative data on AHH activity based on B[a]P hydroxylase activity, benzphetamine demethylase activity, 7-ethoxycoumarin deethylase activity, and cytochrome P-450 content in vertebrates, crustaceans, and bivalves are available in the literature (Vandermeulen and Penrose, 1978 Philpot etaL, 1976). Specific enzyme activities derived from single substrate measurements are limited in their application to complex mixtures of petroleum hydrocarbons (Malins, 1977a, b). MFO absence or activity could determine hydrocarbon retention in... 

Excretion of the electrophilic intermediates as conjugated derivatives has been well identified in terrestial mammals as well as in marine species. All marine species investigated are able to conjugate the oxide intermediates to GSH-derivatives (Bend etaL, 1977). Generally, invertebrates show lower activity than vertebrates. In addition, wide variation in glutathione-S-transferase activity has been observed beween species and substrates used. Reasonable experimental evidence now exists for the enzyme-mediated biotransformation of petroleum hydrocarbons in several marine fish and invertebrate species. 

Immunoassay techniques have been approved for the determination of numerous analytes commonly found in hazardous wastes. Where the EPA method numbers are given in parentheses, these include pentachlorophenol (4010), 2,4-dichlorophenox-yacetic acid (4015), polychlorinated biphenyls (4020), petroleum hydrocarbons (4030), polycyclic aromatic hydrocarbons (4035), toxaphene (4040), chlordane (4041), DDT (4042), TNT explosives in soil (4050), and hexahydro-l,3,5-trinitro-1,3,5-triazine (RDX) in soil (4051). Enzyme-linked immunosorbent assays have been reported for monitoring pentachlorophenol, BTEX (benzene, toluene, ethylbenzene, and o-, m-, and /7-xylene) in industrial effluents. 

Exposure of various invertebrate species to high concentrations of petroleum did not induce mixed function oxidase activity. Enzyme activity was stimulated, however, in a number of fish tissues by petroleum. Different permutations can be addressed as to the significance of basal or induced levels of mixed function oxidases and hydrocarbon toxicity. AHH may have a physiological role in enhancing hydrocarbon clearance but may also increase the mutagenic-carcinogenic potential of hydrocarbons. Both of these concepts have been demonstrated in studies with fish (29,30). Induced AHH levels may permit a more rapid oxidative transformation with concomitant "disappearance" of parent hydrocarbons, but potentially toxic metabolites could be retained in tissues for longer periods (31). It is likely that at the enzymic level the... 

Induction did not occur under our exposure conditions in fish exposed to water saturated with a variety of pure hydrocarbons. The compounds studied are commonly found in other pollutants besides petroleum. It is reasonable to speculate that enzyme induction may not be a common response of fish in the environment to various pollutant hydrocarbons which may be available in the water column for short periods. 

However, there are some potential effects of spilled oil on fish. The impacfs on fish are primarily to fhe eggs and larvae, wifh limited effecfs on fhe adulls. The sensitivity varies by species pink salmon fry are affected by exposure to water-soluble fractions of crnde oil, and pink salmon eggs are very tolerant to benzene and water-soluble petroleum. The general effects are difficnlt to assess and document quantitatively, dne to the seasonal and natural variability of the species. Fish rapidly metabolize aromatic hydrocarbons, due to their enzyme system. 

At the initial stages of a release, when the benzene-derived compounds are present at their highest concentrations, acute toxic effects are more common than they are later. These noncarcinogenic effects include subtle changes in detoxifying enzymes and liver damage. Generally, the relative aquatic acute toxicity of petroleum will be the result of the fractional toxicities of the different hydrocarbons present in the aqueous phase. Tests indicate that naphthalene-derived chemicals have a similar effect. 

The vertical distribution of oxidizing bacteria in the soil profile during the degradation of petroleum substances is dependent on several factors on the content of organic compounds, on the soil type, on the amount of hydrocarbons released in soil air and on the partial pressure of oxygen present in particular soil layers. The development of microorganisms in the soil is conditioned by the temperature, content of gases and pH of the soil. At a low temperature and pH, the formation of enzymes of soil bacteria is reduced. 

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