Screening Degradation And Kinetics Of Pyrene-degradation Fungi

Polycyclic aromatic hydrocarbons(PAHs),especially the high-molecular,is of herodo-toxicity to the organisms for its carcinogenic,teratogenic and mutagenic,which can also accumulate in the biological chain threatening human health.Most PAHs is difficult to be degraded for its structure stability.A large number of PAHs,which comes from sewage of oil and coal industry,atmospheric deposition and soil erodation,is brought into the water through different approaches,resulting in serious pollution.Therefore water PAHs-pollution has drew wide attention of scholars in the world.The principle processes for PAHs removal are currently believed to be microbial transformation and degradation for its economical and high efficiency.In this study,the typical high-molecular PAHs—pyrene was concerned.The study corvered screening of high efficiency microbial,biodegradation condition of the selected fungi and its different metabolic way of pyrene under optimal condition.The results are as follows:1.Under selective pressure of pyrene,six kinds of fungi was isolated from a diversity of PAHs-polluted samples and large fungi like mushroom?shii-take and trametes versicolor subjected to white-rot fungi.Through guaiacol color reaction for laccase production,a strain identified as Aspergillus oryzae HM064501.1 after morphology observation and Molecular biology identification was screened from contaminated soil of urban freeway.2.By measuring and comparing biomass and laccase activity of the fungi,a series of factors like medium,initial concentration of pyrene and environmental conditions are studied systematically.Results indicate that the inorganic salt medium can induce an earlier production of laccase and is identified as the appropriate medium for biodegradation experiment;The maximal biomass and laccase activity of Aspergillus oryzae was obtained under the optimal solution:30 degree,pH=7 and none aeration.And biomass and laccase activity can be better coordinated than the other concentration(30?50?100?150 mg/L)when the initial concentration of pyrene is 80mg/L.3.The single-matrix metabolism and co-metabolism system of glucose-pyrene,salicylic acid-pyrene and sodium succinate pyrene in different mass ratio was examined under the optimal condition in liquid culture.Compared to the 33%efficiency of single-matrix metabolism,co-metabolism can promote that efficiency as a whole.Among them the sodium succinate-pyrene group whose ratio is one got a high efficiency of 51.6%,exceeded all the others.The further analysis suggest glucose can promote proliferation,salicylic acid can induce laccase although a high concentration might infect the active cells and compete laccase.4.Under the optimal condition,a complex co-metabolic kinetics model derived by Criddle was applied to simulate the degradation process of single-matrix metabolism.The single-matrix degradation dynamic equation under lack matrix is Sc=80-Tcb*85.4*(1-e-0.027*t),and It turned out that the biotransformation capacity is 0.2875 and the endogenous inspiration rate is 0.027 after numerical simulation by the software lstopt when the initial concentration of pyrene is 80 mg·L-1 and the dosage of the strain is 85 mg·L-1.