高选择性基因工程菌E.coli SE5000生物富集水体中的镍离子

利用基因工程菌E．coli SE5000对水体中的镍离子进行富集研究．菌体细胞对Ni^2 的富集速率很快，富集过程满足Langmuir等温线模型．经基因改造的基因工程菌不仅最大镍富集容量与原始宿主菌相比增加了4倍多，而且对pH值的变化呈现出更强的适应性．对离子强度及其它共存重金属离子的影响的实验结果表明：Na^ ，Ca^2 ，Cd^2 ，Pb^2 的影响较小，但Mg^2 ，Hg^2 ，Cr^3 和Cu^2 所引起的负面效应较大．金属螯合剂EDTA的存在对基因工程菌的富集行为影响很大．

Bioaccumulation of nickel from aqueous solutions by genetically engineered Escherichia coli SE5000

A genetically engineered E.coli SE5000 strain which simultaneously expressed nickel transport system and metallothionine was used to accumulate Ni²⁺ from aqueous solution. Bioaccumulation process was rapid and followed linearized Langmuir isotherm. A more than four-folds increase of Ni²⁺ binding capacity was obtained by genetically engineered E.coli cells compared with original host E.coli cells. A pH assay showed that genetically engineered E.coli cells could accumulate Ni²⁺ effectively over a broad range of pH (4 to10) and the optimal pH was 8.6. The presence of 1000mg·L^-1 Na⁺ and Ca²⁺, or 50mg·L^-1 Cd²⁺ or Pb²⁺ did not have obvious effects on Ni²⁺ bioaccumulation, while Mg²⁺, Hg²⁺, Cr³⁺ and Cu²⁺ posed severe adverse effects on Ni²⁺ uptake by genetically engineered E.coli. The presence of EDTA could inhibit nickel uptake.