There is no doubt that heavy metal contamination has detrimental effects on our environment and our health.For the sake of solving this challenging problem,our team comes up with the idea of this case.In our project,we intend to construct two plasmids to carry some specific elements and flocculation gene into the E.coli host,so that we can detect whether the environment is contaminated with heavy metal ions and report the concentration of them.Owing to the flocculation gene,we can collect the reconstructed bacteria just in case of repeated pollution.We focus on trace contaminates detection and set the goal of standardizing the whole detection protocol.