The Study Of Screening, Identification And Degradation Characteristics Of A DEHP Aerobic Degrading Bacterial Strain

Phthalic acid esters (PAEs) are a class of refractory poisonous deleterious organic compounds. Di-(2-ethylhexyl) phthalate (DEHP) is widely used and baneful for people's health among all the PAEs. Currently, the research on biodegradation of DEHP has become a hot topic at home and abroad. The study covers screening of degrading strain, fitting of kinetic model and application in sludge-amended soil. However, the study of the optimum culture conditions for specifically degradation stain at high concentrations of DEHP and the various forms fitting in the kinetic model for degradation are relatively small.This thesis is part of National Nature and Science Foundation Project《The Study of Bacterial Strains Screening and Degradation Characteristics in PAEs Wastewater Biological Treatment》(Project No.50778036). In the study, DEHP was took as the experimental pollutant, and an aerobic degrading bacterial strain Y-1 that could degrade DEHP strongly was screened and isolated from the activated sludge at Jilin chemical factory sewage treatment plant using the gradient acclimatization technique. Orthogonal experiment was set up to access the optimum experimental conditions. The results showed that the temperature (A), pH value (C) and oscillation rate (D) had highly significant effect on the degradation of DEHP.In addition, at the optimum conditions, the biodegradation characters of the strain Y-1 at the conditions of different initial concentrations of DEHP and the adding of glucose carbon resource were also studied. The results showed that the biodegradation ratios of strain Y-1 at different initial concentrations of DEHP were between 0.8572-0.9814, which was a high degradation efficiency range. Meanwhile, the remaining degradation concentration data were fitted in the linear, exponential and corrected first-order reaction models by the SPSS software and the data fitted the third model's kinetics characteristics. When adding different concentrations of glucose carbon source, the biodegradation ratios of strain Y-1 at 1000mg/L DEHP were 0.7499 and 0.6183, also the degradation data were fitted in the models and the results showed that adding a small amount of glucose carbon resource could reduce the uncertain factors in the degradation of DEHP, while overusing it would depress the degradation of DEHP.At last, 16S rDNA gene of the strain Y-1 was amplified from the genomic DNA by PCR. The strain is identified as Rhodococcus. It was registered into the GenBank,and the accession number is HM008918.