Part:BBa_K3036005:Experience

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Applications of BBa_K3036005

As for the killing switch, we refer to the arabinos-induced suicide system of 2019-BNU_China, which uses arabinos-induced promoter (pBAD) to express the toxic protein MazF. So when the patient takes in arabinos, the engineering bacteria will commit a suicide. When we repeat the experimental methods provided by 2019-NEU_China, we found that the results are not good. We repeat 5 times and no expected outcome was achieved. As we thought maybe we failed to build the part, our advisor Xiaoting Luan reminded us that our bacteria grow very fast——2h to achieve the logarithmic phase, 4h to reached the plateau phase, 6h to recession phase.

We also got in touch with 2019-BNU_China and discussed the method. So we shorten the experiment time and after we did that, the outcome proved that our part was effective.

Bacteria are in the logarithmic phase. It can be seen that the CFU of bacteria decreased significantly after arabinose induction.

Bacteria are in the logarithmic phase. It can be seen that the CFU of bacteria decreased significantly after arabinose induction.

Bacteria are in the logarithmic phase. It can be seen that the CFU of bacteria decreased significantly after arabinose induction.

Normal bacteria entered the decay stage, but arabinose cut down the quantity of the bacteria and in turn delayed the decay stage, so there were colonies in the induction group and no colonies in the normal group.

User Reviews 2021NJMU-China

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User Reviews 2022NJMU-China

To validate the function of our arabinose-induced kill switch, we inoculated 3% fresh bacterial solution in the culture medium and added 0 mM and 10 mM arabinose respectively as the control and experimental groups. Every 1 hour, 2 hours, and 4 hours, we draw 100 ul of bacteria to the smear plate and cultured at 37 ℃ overnight. The colony counts are shown below.

colony count in the kill switch verification after dilution (the dilution multiple is 109) (A) 1h. (B) 2h. (C).3h

kill switch verification

As shown in the figure above, in one, two, and four hours, the numbers of colonies with arabinose induction are all lower than that without arabinose induction. This indicated the effectiveness of our kill switch.