Team:HBUT-China/Demonstrate

Response to nickel ions：

We added nickel ions in the medium of strain K2304002. After 2h (200rpm, 37 ℃, LB), we centrifuged the culture medium at 12000 r / min. The red precipitate appeared at the bottom of the centrifuge tube，while the blank control group produced very little, or none of the red precipitation. This indicates that KL2304002 can be induced by Ni ions to produce RFP.

Specific response:

In order to detect whether strain K2304002 is also induced by other ions,

We mixed samples using Cd^{2 +}, Co^{2 +}, Cu^{2 +}, Fe^{3 +}, and Ni^{2 +}in LB medium, with a concentration of 0.01 mmol / L .

We cultured the samples at 200rpm, 37 ℃ overnight.

The next day we observed them with a fluorescence microscope. Excitation light is Blue background light.

Clearly, only the sample with Ni ions showed red fluorescence, the other groups had no red fluorescence. Note that the iron ions reacted with the substance in the culture medium，so that there is an impurity in the field of view.

Qualitative testing：

K304002 was cultured at different concentrations of nickel ions, and the fluorescence intensity was measured every hour. We found that different concentrations of nickel ions caused inconclusive differences in fluorescence intensity.

Therefore, we tried to find a way to perform qualitative testing. We used different concentrations of nickel ions to induce the strain in OD0.8, and detected the fluorescence intensity every other hour by fluorescence spectrophotometer. And finally we found with a nickel ion concentration of 10-6mmol / L to 10-4mmol / L, that the correlation between fluorescence intensity and nickel ion concentration is the highest. So it has the application value of qualitative detection.

This is the conclusion we have made so far, and if we continue to experiment, we believe we can find a better application mode, or an exact detectable interval. After that, we will be able to further study its measurement accuracy.

Application：

We designed a kit, including 10ml centrifuge tubes, filter columns (containing 0.22 M filter membrane), the national standard concentration of nickel ion solution 50ml(3μg/L), pure water 20ml, engineering bacteria 5ml.

Here is the Instructions：