Research On The Heavy Metals Bloaccumulation By Jujubel Metallothionein(MT) Engineering Beacteria System

Scale experiments were made on culturing jujube metallothionein engineering bacteria (pGEX-ZjMT-B).But the resach of applying these engineering bacteria to different kinds of heavy metals ion bioaccumulation is only in its infancy and theory can’t into practice,so study in a deep-going way on the heavy metals ion bioaccumulation properties by these engineering bacteria is very important.This resach started with the basic theories, applied pGEX-ZjMT-B to heavy metals ion removal processes, observated these processes and made a deep study of the influencees which were produced by pH value, coexistence metals ion, complexing agent, temperature and so on, put forward the theoretical and experimental data support for treatmenting the heavy metal ions in wastewater of industry.This thesis has three parts:Part one:observate the toxicity function of Pb2+,Mn2+,Cd2+,Cu2+,Ni2+,Zn2+and Hg2+seven kinds of heavy metals ion towards pGEX-ZjMT-B. add Pb2+,Mn2+,Cd2+,Cu2+,Ni2+and Zn2+of different concentrations in the culturemedium to study the toxicity function of the heavy metal ions towards pGEX-ZjMT-B. choose Pb2+,Cd2+,Mn2+and Ni2+for enrichment rate and enrichment of quantity test.Part two:In the experiment of Pb2+and Cd2+’s enrichment in simulated wastewater by pGEX-ZjMT-B,resach on the influencees which were produced by ph value,coexistence metal ions,temperature and so on seven factorsPart three:In fore kinds of actual wastewater,observate the enrichment circumstances of heavy metal ions by pGEX-ZjMT-B.The first part of the experimental results are as follows:1)In high concentration of Pb2+,Mn2+,Cd2+,Cu2+,Ni2+and Zn2+pGEX-ZjMT-B can grow well all. No significant impact was measured, the toxicity function of the six heavy metals ion towards pGEX-ZjMT-B is little.but the toxicity function of Hg2+towards pGEX-ZjMT-B is big.2) Change the concentration of Pb2+and Cd2+, no significant affect on the growth of pGEX-ZjMT-B. change the concentration of Mn2+,and Ni2+,the affect on the growth of pGEX-ZjMT-B is followed.change the concentration of Cu2+and Zn2+, the affect on the growth of pGEX-ZjMT-B is bigger.3)For Cd2+, Mn2+and Ni2+, the enrichment rates are fast all,and over90%enrichment of quantity is finished in ten minutes basically. the enrichment rate for Pb2+is slow relatively,but it have higher bioaccumulation capacities and the enrichment rate is over90%.4)PGEX-ZjMT-B showed high accumulation ability of Pb2+, the accumulation ability of Cd2+is followed.so choose Pb2+and Cd2+conduct the next experiments.The second part of the experimental results in simulated wastewater are as follows:1)Change pH Value, the bioaccumulation capacities of Pb2+and Cd2+by PGEX-ZjMT-B have no significant fluency.but the best pH extent are5-7. 2)The common metal ions Na+、Ca2+、Mg2+have positive effect on Pb2+bioaccumulation and Cd2+bioaccumulation under low concentration.3)The influence of coexistence metal ions for Pb2+bioaccumulation is Zn2+>Ni2+>Cu2+>Mn2+, and for Cd2+, the influence of coexistence metal ions is Mn2+>Ni2+>Zn2+>Cu2+4) Complexing agents EDTA and citric acid have positive effects on Pb2+bioaccumulation, but have adverse effects on Cd2+bioaccumulation.and for positive effects on Pb2+bioaccumulation or for adverse effects on Cd2+bioaccumulation, the effects of EDTA are bigger than citric acid.5)Both glucose and lactose have adverse effects on Pb2+bioaccumulation and Cd2+bioaccumulation.6)The increased concentration of bacteria can affect Pb2+bioaccumulation and enrichment rate increases with the increased concentration of bacteria,but no significant affect on Cd2+bioaccumulation.7)The change of temperature has an influence on Pb2+bioaccumulation and Cd2+bioaccumulation, and both have the biggest enrichment rate at17℃.The third part of the experimental results in actual wastewater are as follows:1)In actual wastewater, heavy metals Pb2+,Cd2+,Ni2+,Mn2+,Zn2+,Hg2+Cr3+can be concentrated by pGEX-ZjMT-B to a certain degree,and in high heavy metals ion concentration of Percolates wastewater and Ore-dressing wastewater, the enrichment rate is bigger than in low heavy metals ion concentration of Northwest river wastewater and Jinyang Lake water.2)Engineering bacteria pGEX-ZjMT-B have good bioaccumulation effect on Pb bioaccumulation,especially in high heavy metals ion concentration of Percolates wastewater, the enrichment rate can reach100%.