| Research Abstract |
Cytochrome P450 (P450) are widely distributed in the biosphere and catalyze a remarkably broad range of chemical reactions on an equally broad range of substrates. Therefore, the P450-producing bacteria are good candidates for biodegradation of hazardous organochemicals.
In this study, 10 strains of P450-producing bacteria were isolated from M9 medium containing a P450-inducer as the sole carbon source from the environment. Strains EP1 to EP7 utilizing 2-ethoxyphenol as the sole carbon source were isolated from the soil of a weed-filled field, the water of a paddy field, laboratory effluent, domestic effluent, river water and activated sludge. Strain MP1 and MP2 utilizing 2-methoxyphenol were isolated from oil-polluted soil and activated sludge, respectively. Strain CP1 utilizing camphor was isolated from the soil of a weed-filled field. This suggests the distribution of P450-producing bacteria in the environment. Metyrapone (2-methyl-1, 2-di-3-pyridyl-1-propanone) inhibited the growth
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of P450-producing bacteria on the media containing a P450-inducer as the sole carbon source, strongly suggesting that the P450 is involved in the catabolism of the inducer.
2-Ethoxyphenol-induced P450EP1A from Rhodococcus sp. strain EP1 and P450EP4 from Gordonia sp. strain EP4 were purified to apparent homogeneity. The P45OEP1A and P450EP4 showed a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with molecular weight of about 45 kDa and 47kDa, respectively. The purified P450 degraded 2-ethoxyphenol in an assay system composed of spinach ferredoxin, spinach ferredoxin oxidoreductase and NADPH.In addition to 2-ethoxyphenol, the P450EP1A metabolized 2-methoxyphenol, 1, 1, 1-trichloroethane, carbon tetrachloride, benzene and toluene. P450EP4 metabolized not only 2-ethoxyphenol but also trichloroethylene, dichloroethane, 1, 1, 1-trichloroethane and chloroform. These P450s can display a remarkable chemical flexibility toward substrate. Thus, P450EP1A and P450EP4 may be useful for the removal of hazardous organochemicals from environment. Less
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