Introduction

1. Why do we detect mercury?

   Normally, there wont be such amount of heavy metal be contained in edible oil. Edible oil excessive mercury is because methyl mercury will be hoard in animal internal organs after eating by them. And recycled oil was made from animal internal organs . After we eat recycled oil into our body, it wont be metabolized easily and lead to serious disease. Due to the reasons above, we decided to detect this heavy metal.[1]

2. The harm of mercury

   It's common knowledge that Methyl mercury is neurotoxin . It represses cell division and restricts motility of electronic ions. It can also interfere with growing brain structure. Besides, methyl mercury can also result in cardiovascular disease like myocardial infarction, Ischemic Heart Disease，hypertension and irregular pulse.[2]

3. Taiwanese regulations
   • Edible Fat and Oil Sanitary Standards Article 2: The maximum allowance for Heavy Metal and Erucic acid: Mercury 0.05 ppm
   • Edible Rice and Heavy Metal Restriction Standard Article 2: permissible percentage limits for edible rice and heavy metal: less than 0.05ppm

Circuit Design

MerB can turn Methyl mercury into Hg2+.MerR can combine with Hg2+ and change the structure of DNA. And DNA can be trancripted easier. PmerT is controlled by MerR. PmerT cannot be transcripted because MerR changes the shape of PmerT. In short, the whole reaction will continue if MerR combines with Hg2+.[3][4]

Result

1. Whether Mercury can enter e.coli or not
   1. Method

      Detection of the amount of toxins in the e.coli.

      1. Add 100μl of DH5α and 900μl of LB broth into the tube and incubate for 1hr.
      2. Centrifuge at 4000rpm for 3min and clicard 800μl of the supernatant

      3. Plate each 100μl of the bacteria onto the dishes and spread.

         Incubate the plates at 37℃ overnight

      4. Prepare each concentration of the toxin.

         Statutory standards *100 / *10 / *1 / *0.1 / *0.01

      Next day

      1. Prepare 16 microcentrifuge tubes.(5 kinds of concentration *3 timings+control)

         Add 500μl of DH5α to each tube.

         Centrifuge all tubes at 4000rpm for 3min.

         Remove the supernatent.

      2. Add 1000μl of the toxic solution each time.

         Follow the concentration and 3 timings(0.5hr / 1hr / 1.5hr).

      3. 1. Add 0.5cc of ddH₂O and mix with the bacterias
         2. Centrifuge at 13000rpm for 30 sec
         3. Remove the water
         4. Repeat step1~step3 for three times

      4. Add 1cc of ddH₂O and mix with the bacterias

         Centrifuge at 13000rpm for 30sec.

         Remove 700μl of the supernatant

      5. Kill the bacteria:

         1. Put all the tubes in the Liquid nitrogen
         2. When they freeze,heat them at 100℃
         3. Repeat step1~step2 for 3 times
   2. Result
   3. Discussion
2. Whether e.coli is alive in the poisons, condition or not
   1. Method
   2. Results
   3. Discussion
3. The relation between the concentration of Mercury and illumination of RFP
   1. Method
   2. Results
   3. Discussion

Reference

• [1]J. Agric. Food Chem., 1975, “Metabolism of mercury, administered as methylmercuric chloride or mercuric chloride, by lactating ruminants”.23 (4), pp 803–808,DOI: 10.1021/jf60200a013 Publication Date: July 1975
• [2]Knowledge、Attitude、Practice and risk assessment of mercury exposure through the consumption of fish from the mercury containminated area邱宇昕,JULY/2007
• [3]Brown, N. L., J. V. Stoyanov, et al. (2003). "The MerR family of transcriptional regulators." FEMS Microbiol Rev 27(2-3): 145-163.
• [4]Park, S. J., J. Wireman, et al. (1992). "Genetic analysis of the Tn21 mer operator-promoter." J Bacteriol 174(7): 2160-2171.