Isolation, Identification And Degradation Characteristics Of Two Bacterial Strains Degrading NP And BPA

Environmental hormone, was generally considered as the third generated environmental pollutants. NP and BPA were two representative EEDs. Biodegradation of NP and BPA was one of the most effective ways to remove NP and BPA in natural environment. Thus, it was an important meaning to conduct the research of biodegradation of NP and BPA. In this paper, bacterial strains designated as N1,N2,N3 and B2 were isolated, purified and sorted from acclimated activated sludge in oxidation ditch of Shanghai Tianshan Wastewater Treatment Plant with NP and BPA as the sole carbon and energy source respectively. The residual rate of NP and BPA was quantitative detected by uv spectrophotometry. The degrading characteristics were mainly discussed by orthogonal design. Monod equation was adopted as the kinetics model. The results mainly showed that:(1) The degrading conditions for strain N1,N2,N3 and B2 were optimized by tests in shaking flasks and orthogonal tests. The results showed that the optimum conditions for strain N1 degrading NP were 35℃, the initial pH 5.5, initial NP concentration 10 mg/L in salt medium, the degradation rate reached 79.64% in 24 h; the optimum conditions for strain N2 degrading NP were 30℃, the initial pH 7.0, initial NP concentration 10 mg/L in salt medium, the degradation rate reached 71.04% in 24 h; the optimum conditions for strain N3 degrading NP were 35℃, the initial pH 5.5, initial NP concentration 20 mg/L in salt medium, the degradation rate reached 67.55% in 24h; the optimum conditions for strain B2 degrading BPA were 30℃, the initial pH 7.0, initial BPA concentration 10 mg/L in salt medium, the degradation rate reached 78.68% in 24 h.(2) Based on the above optimal temperature and initial pH value, the kinetics analysis of strain N1,N2,N3 degrading NP and strain B2 degrading BPA under different initial NP and BPA concentrations respectively showed that the degradation reaction conformed to Monod equation when the initial substrate concentrations were 5～40mg/L and the kinetic parameters of Ks and um from Strain N1,N2,N3 and B2 for the model were 4.32,4.66,5.11,8.36 and 0.1778,0.1086,0.1823,0.1119, respectively.(3) Strain N1 and B2 were identified preliminarily as Citrobacter sp. and Bacillus sp. respectively according to their sequence analysis of 16S rDNA as well as morphological, physiological and biochemical characteristics. Such two strains with certain application value and the potential of extension were first reported.