Isolation And Characterization Of Polychlorinated Biphenyls-degrading Bacterium And Its Applications

The toxicity, carcinogenicity, persistence and tendency of polychlorinated biphenyls(PCBs) to bioaccumulate are of globle environmental and health concern. Bioremediation of contaminated soil is green, economical and promising, which can make up for the deficiency of physical and chemical technology.In this study, an enrichment culture is domesticated from soil and sediment contaminated by PCBs and high-efficiency degradation strains were isolated. The patterns of the degradation of biphenyl and PCBs in the water by enrichment culture and PCBs-degrading bacteria were studied afterwards. Meanwhile the degradation of PCBs in the polluted soil adding the exterior microorganism was studied by lab simulation as well as field investigation. It can provide theory basis and experience about engineering application for bioremediation of PCBs polluted sites. The main results of this research are as follows:(1) The analytical methods of biphenyl and PCBs in the water was established based on constructive sampling, liquid-liquid extraction, GC-MS and GC-ECD. The recovery rate of the methods is89.3%-97.7%and91.8%-105.9.(2) A biphenyl and PCBs-degrading strain was isolated. By morphology analysis, carbon utilization analysis, physiology and biochemistry analysis and16s rRNA sequencing, the strain was identified as Sphingobium fuliginis and named HC3. Stain HC3can degrade biphenyl completely in48h and the optimal environment conditions for degradation is:pH7.0,30℃,(3) A stable biphenyl and PCBs-degrading enrichment BP-Y was obtained via continuous domestication and passage.. In the degradation process of biphenyl, enrichment BP-Y can produce a yellow Intermediates. It can probably be2-hydroxy-6-ox-6-enylhexa-2,4-dienoate (HOPDA), which has the largest absorption peak of340nm on the UV-VIS spectra when pH is6.2. Enrichment BP-Y can degrade biphenyl completely in36h.(4) Sphingobium fuliginis HC3and enrichment BP-Y has high degradation ability for commercial PCBs mixtureAroclor1242. When the initial concentration of Aroclor1242is10mg/L, Sphingobium fuliginis HC3and enrichment BP-Y can degrade70.9%and97.9%di-CBs in120h. Sphingobium fuliginis HC3and enrichment BP-Y can degrade81.5%and78.7%tri-CBs in120h. Sphingobium fuliginis HC3and enrichment BP-Y can degrade83.3%and39.3%di-CBs in120h. Degradation trend of low chlorinated PCBs is obvious and the maximum amount of degradation happened within the first24h. What is more, Degradation trend of high chlorinated PCBs by Sphingobium fuliginis HC3and enrichment BP-Y is hard to see.(5) In lab simulation, the degradation percentage of∑PCBs by Sphingobium fuliginis HC3and enrichment BP-Y was28.1%and29.1%after5days, and45.4%and59.2%after10days. The degradation effect was significant. In field investigation, the degradation percentage of∑PCBs by Sphingobium fuliginis HC3and enrichment BP-Y was28.1%and29.1%after5days, and45.4%and59.2%after10days, while the degradation percentage of control was11.8%. The degradation effect of the experiment group doubled compared with control group. It is indicated that strain HC3and enrichment BP-Y both have great potential for remediation of contanminated soil..