Screening Lead-resistant Strains From Highways Of Chengdu And Exploring Biological Character

The research got the soil from the vicinity of chengyu,chengmian, chengya,chengguan and chengnan highways.Diluted the leachate.Got strains by the 200mg/L concentration of Pb²⁺ and marked them. By increasing concentrains in turn,got the highest Pb²⁺ concentrains of lead-resistant strains of the five highways,compared the results.The results indicated that lead-resistant level was relate to the polluted time.According to the results of the comparison ,screened and got the strain of the highest lead-resistant. Analysed the morphologic characters, biophysical and biochemical characters of the strain.By the accurate appraisal of 16sDNA,confirmed it as Bacillus subtilis of Bacillus Cohn.Measured the biological activity:the strain entered into the stationary stage after be cultivated after 18 hours ,and after 30 hours entered into the contabescence stage.So the best cultivation time is between 18-30 hours.And the optimum growth temperature was 37℃, optimum pH was 8, Optimum Inorganic Salt Concentration was 3%。Inoculated the strain in the liquid culture medium of respective Pb²⁺ concentrains, measured the effects of Pb²⁺ concentrains to the activity of the strain. The result indicated that the activity of the strain fell along with the Pb²⁺ concentrains.Because of the situation of the many heavy metal mixed in actual contaminated situation, streaked cultivate into single Cu ²⁺,Zn²⁺,Cd2+,Ni²⁺å’ŒMn²⁺ and the five heavy metals compound culture medium,observed that the srains had definite resistance to the other heavy metals,specially still grew well in many heavy metal compound culture medium.The research emphasized the adsorption effect of the strain to the Pb²⁺. Respectivly measured the removal efficiency of Pb²⁺ under the condition of different adsorption time ,microbial Populations, pH value ,Carbon source and Nitrogen source.The result indicated that the best adsorption condition : microbial Populations was 1g/L,time was 20min, pH was 5.5, Carbon source was sucrose and Nitrogen source was (NH4)2SO4.The best adsorption efficiency was abourt 85.25%.Despite the strain had definite resistance to the other heavy metals,the influence of many heavy metals to the adsorption efficiency was the actual practical value.Added Fe3+,Cd²⁺,Al3+,Mn²⁺, Cu²⁺,Zn²⁺ and the mixed fluid into the 100mg/L of Pb²⁺ concentrains.Absorpted under the best condition. The result indicated that besides the adsorption efficiency under condition of Cd²⁺, Zn²⁺ had tiny improvement ,the others both fell.Specially under mixed condition ,the adsorption efficiency fell abourt 10%.So when using the strain into asorption ,should deal with the sample and wipe off some other heavy metals,in order to reduce the interference to the adsorption.After above the experiments ,got some basic situation of the adsorption,and the research wanted to get a strains of better adsorption effect by NU mutagenesis,DES mutagenesis and mutagenesis complex. Firstly observed the surviving situation under the NU mutagenesis of five times.Choosed the surviving strain of the five times,measured each Pb²⁺ final concentrains (compared to the adsorption efficiency of the orginal strain).And finded that the strain by 1 min had a best removal efficiency:93.45%.But under the DES mutagenesis and mutagenesis complex had not get ideal strains.The experimental method and result of this article maked for the adsorption mechanism research of microbe to the heavy metals,and provided a effecive resolvent to the pollution of the Pb²⁺.The adsorption condition was help to put biosorption of heavy Metals apply into decontaminating the heavy metals contanmination.