| The bioremediation methods occupy dominant position in heavy metals pollution control due to its economy, ecological benefits and other advantages. As the main body of ecological remediation, microorganism play an important role in heavy metals pollution control.In this paper, we got the experimental soil sample from the root of tolerant lead & zinc plant Nerium indicum Mill which grew well in pot experiment about Hunan Zixing lead-zinc mine.Some charicteristics of screening and acclimation resulting strains were studied, such as tolerance, physiological and biochemical characteristics.Besides, taxonomic identification, SEM and FTIR was researched in this paper.The specific experimental conclusions are summerized as follows:(1) After a series of separation, screening and acclimation experiment, we obtained 26 strains of lead and zinc tolerant bacteria, No. B1-B26. By comparing the OD600 about 26 strains bacteria in the culure medium which were on the design of different concentration gradient of Pb (Ⅱ), Zn (Ⅱ), we identified B1, B4, B14 as the dominant strains because of their higher growth. The Pb (Ⅱ) and Zn (Ⅱ) maximum tolerated concentration of B1, B4, B14 was up to 800mg/L,800mg/L,600mg/L.(2) After studing on the enrichment characteristics of three strains of dominant bacteria we found that:at temperature of 30 ℃, the initial concentration of 50 mg/L, the rate of the shaker at 180 r·min-1, pH5.0, the cultured time of 50min, the initial bacteria amount of 0.06g, the removal efficiency of B1 could reach 84.22% and 70.66%; at temperature of 30℃, the initial concentration of 50 mg/L, the rate of the shaker at 180 r·min-1, pH6.0, the cultured time of 50min, the initial bacteria amount of 0.18g, the removal efficiency of B4 could reach 72.63% and 54.17%; at temperature of 30℃, the initial concentration of 50 mg/L, the rate of the shaker at 180 r·min-1, pH4.0, the cultured time of 60min, the initial bacteria amount of 0.10g, the removal efficiency of B14 could reach 77.56% and 50.63%.The above results show that these strains of dominant bacteria have a good application prospect in repairing lead and zinc contaminated soil and the treatment of wastewater containing Pb (Ⅱ) and Zn (Ⅱ)(3) These strains of dominant bacteria were examined for colony morphology, gram staining and 16S rDNA molecular identification.Through blast comparing of 16S rDNA sequence inputting NCBI obtained with the highest homology with known sequences of the bacterial 16S rDNA sequences.According to the morphology of the colony, gram staining and 16S rDNA molecular identification.Finally, B1 was identified as Bacillus cereus or Bacillus anthracis, B4 was identified as Aneurinibacillus aneurinilyticus, B14 was identified as Micrococcus luteus.(4) Scanning electron microscopy revealed that, in the culture medium containing Pb (Ⅱ) and Zn (Ⅱ), distortion occurs over the medium cell, some of cells ruptured part or aggregation.And a large number of crystals and floc or spherical precipitation were produced on the cell surface. Analysis of the FTIR indicated that cells of B1, B4, B14 were rich in -OH,-N-H, alkyl, CONH-, OC-O-,-PO43-and any other active groups. By comparing the infrared spectrogram of mycelium on before and after the adsorption, we found that -O-H,-N-H, alkyl, CONH- were the main active groups that adsorpting, complexing or chelating metal ions or atoms.The binding reaction between heavy metals and active groups on strain surface is the main mechanism that adsorpted Pb (Ⅱ) and Zn (Ⅱ)... |
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