Study On Co-Degradation Of Benzo[a]Pyrene And Their Synergy By White Rot Fungi And Bacillus Sp.

In this study,fungi and bacteria were taken as the research objects,and the purpose of microbial degradation of PAHs in soil was studied.The resistant strains to PAHs were isolated,screened and acclimated from soil to explore the removal efficiency of benzo[a]pyrene by microorganisms under different ratios and culture conditions,and the relationship between biodegradation and biosorption in the removal process.The main research results are as follows:(1)Two strains with tolerance to benzo[a]pyrene were isolated from the contaminated soil around an abandoned pharmaceutical factory in Xuzhou.After enrichment and domestication,they were identified as Bacillus sp.by16 Sr DNA.Within15 days,the removal rates of PAHs reached 56.3% and 60.2% respectively.(2)Removal efficiency of benzo[a]pyrene by mixed bacteria with different proportion and different amount of bacteria.When the inoculation volume ratio of fungi to bacteria is 1:1 and the amount of bacteria was 10% of the volume of culture medium,the removal rate of benzo[a]pyrene reached to 80.12%,the highest in 15 days.The results showed that the activity of manganese peroxidase was higher than that of the other two enzymes.In the enzyme system secreted by bacteria,the activity of ophthalate oxygenase was the highest.The degradation process of benzo[a]pyrene was roughly inferred by determining the possible intermediate products of PAHs in the degradation solution.(3)Single factor experiments were conducted to determine the effect of microbial removal of benzo[a]pyrene under different conditions.On the basis of single factor experiment,Plackett Burman experiment was carried out by selecting six factors including p H,temperature,shaking speed,PAHs concentration,microbial proportion and inoculation amount.The results showed that p H,temperature,shaking speed and PAHs concentration had significant effects on the removal rate of benzo[a]pyrene.The results showed that the optimal combination was p H 7.5,temperature 28?,rotational speed 170 r/min,PAHs concentration 26 mg/L,and the predicted degradation rate of benzo [a] pyrene was 82.01%.(4)The relationship between biodegradation and adsorption of benzo[a]pyrene by microorganisms was studied.Under the condition of mixed bacteria,biosorption plays a major role in the early stage and biodegradation plays a major role in the later stage.It was found that the pseudo second order kinetic model could better describe the biosorption process and the pseudo first order kinetic model could better describe the biodegradation process.