Induction Of Cytochrome P450 And Preliminary Study On Biodegradation Of Pentachlorophenol By White-rot Fungus

Refractory organics are the toxic compounds which can't be degraded or can be degraded very slowly by microorganism. They can exist in the environment persistently and be accumulated in the animals'fat. Refractory organics have become one of main problems in environmental protection. White-rot fungus is the hotspot of the study on the biodegradation of pollutants internally and externally due to its powerful degrading ability and special metabolic type. White-rot fungus P. chrysosporium is the model fungus about the metabolism of lignin and refractory organics. It offers foundation for studying the function of P450 more to ascertain the inductive ability of some refractory organics to P. chrysosporium's cytochrome P450. Pentachlorophenol is the model compound about the degradation of chlorophenol by white-rot fungus. It's good for ascertaining the mechanism of degradation of refractory organics by white-rot fungus and helping engineering apply as theoretical basis to study the metabolites of PCP.The reduced P450-CO difference spectrum was used to determine the content of P450.It was explored to determine PCP quantitatively by high-performance liquid chromatograph (HPLC) and to judge PCP, tetrachlorohydroquinone qualitatively by gas chromatograph (GC). The change of concentration of PCP was determined by HPLC. The metabolites of PCP in high nitrogen culture were identified by the HPLC, GC, GC-MS.The main results of study are below. P450 could be induced clearly by the proper dosages of benzoate acid, naphthalene and PCP except o-, m-, p- dichlorophenol. P. chrysosporium depended on the intracellular enzymes to degrade PCP on the nonligninolytic condition, but on the ligninolytic condition, it could degrade PCP more effectively by the extracellular lignin-degrading enzymes and the intracellular enzymes. PCP was initially metabolized to pentachloroanisol by intracellular enzymes and wasn't oxidized to tetrachlorohydroquinone by a monooxygenase. It showed that the initial degradation of PCP probably had no relationship with P450. The novel findings were lead to by the study: 1) The cytochrome P450 can be induced by PCP, but its initial degradation probably had no relationship with P450. 2) On the nonligninolytic and ligninolytic condition, the intracellular enzymes of P. chrysosporium can degrade PCP, and the initial metabolite is pentachloroanisol methylated from PCP.