Biodegradation Of Triphenyltin In Water And Sediment By Klebsiella Pneumoniae

The biodegradation of triphenyltin by Klebsiella pneumoniae was studied in the research, including biodegradation capability of triphenyltin in water and sediment, effect of heavy metal ions on triphenyltin enzymatic degradation and biodegradation mechnisam.Klebsiella pneumoniae, a triphenyltin degrading bacteria, was obtained from the long-term triphenyltin polluted sediment. The effect of environmental factors on degradation efficiency of TPhT was investigated. The results showed that NaCl concentration, H2O2 concentration, nutrient salts, biosurfactant rhamnolipid were the important factors on triphenyltin degradation. The strain was able to tolerate NaCl of high concentrations. Adding nitrogen and phosphorous into medium can promote the process of strain growth and metabolism. Biosurfactant rhamnolipid was added in the process of degradation by K. pneumoniae, the result displayed that rhamnolipid could accelerate the degradation process. The strain was able to tolerate Cu2+, Cd2+, Pb2+ and Zn2+ into medium.Adding Cu2+,Zn2+ into medium promoted the degradation of TPhT, while Cd2+ and Pb2+did not show obvious effect on degradation processes.In water and sediment system, the removal percentage of TPhT was up to 55% in the process of degradation by K. pneumoniae and indigenous microorganism, The degradation efficiency of TPhT was up to 80.06% when sediment content was 10g/L. Repid and slow stages of TPhT degradation occurred during 0-9d period.The optimum conditions for triphenyltin degradation was temperature 30℃, pH 6,and the strain was able to remove TPhT at high NaCl concentrationon.The influence of different metal ions and ways of adding metal ions on triphenyltin enzymatic degradation was investigated using enzyme obtained from K. pneumoniae. The strain was able to tolerate K+, Mg2+, Cu2+, Ca2+and Fe3+ at high concentrations. High concentrations of Zn2+ and Fe2+ had some toxic effects on the strain, thus affecting its growth. The endoenzyme activity was enhanced by metal ions such as K+, Mg2+, Zn2+, Cu2+ and Fe2+ at certain concentrations. In the presence of 30 mg/L Mg2+, the removal percentage of TPhT was up to 77.22%. Fe3+ restrained the enzyme activity at certain concentrations. Adding K+, Mg2+, Zn2+, Cu2+ into medium promoted the enzyme activity, among which Mg2+ demonstrated removal percentage of TPhT up to 85.66%. Calculated by Lineweare-Burk plot, the constant Km and Vmax were 0.06 mmol/L and 0.02 mg/L/min, respectively, which indicated good affinity of endoenzyme to TPhT.Mechanism studies confirmed that the structure of K. pneumoniae mainly include-OH, N-C=O,-CH3,-CH2 and-COOH. Proteins and carbohydrate were the principal components of the stain. The components and structure of the stain remain intact after TPhT degradation. TPhT was transferred to SnCl2,SnO2 after 5d degradation. Flux and active transport of organism and ions during the experimental process were observed.Baeterial cells of K. pneumoniae tended to aggregate together in TPhT polluted envirotunent.TPhT were utilized after coming into cells as nutrition.