Team:SDU-Denmark/project-p

From 2010.igem.org

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(Experiment 2)
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==== Experiment 2====
==== Experiment 2====
The experiment described above was repeated in a more controlled environment. This means that there were no changes as to how the plates or bacterial cultures were prepared, so we refer again to [http://2010.igem.org/Team:SDU-Denmark/protocols#Photosensor_characterisation PS1.1] in regards to how this was done. The difference lies in the setup of the light-controlled environment. What we did this time was that the plates was illuminated from above by a single light source in an otherwise completely dark environment, we prepared a cut-out so that the light would only hit one half of our plates and the other half would remain in the dark. Since the problem with the last experiment was that the light source was just normal white light (which contains a lot of different wavelengths), this time around we used an optical filter so that only light with a wavelength of around 470nm could pass through, which resulted in a blue light shining down on the plates. The light-source itself was a run-of-the-mill flashlight, with a blue light filter installed in front of the lens. To eliminate the effect of temperature gradients inside the incubator, the three samples were placed in a triangle formation in the center of the incubator. <br>
The experiment described above was repeated in a more controlled environment. This means that there were no changes as to how the plates or bacterial cultures were prepared, so we refer again to [http://2010.igem.org/Team:SDU-Denmark/protocols#Photosensor_characterisation PS1.1] in regards to how this was done. The difference lies in the setup of the light-controlled environment. What we did this time was that the plates was illuminated from above by a single light source in an otherwise completely dark environment, we prepared a cut-out so that the light would only hit one half of our plates and the other half would remain in the dark. Since the problem with the last experiment was that the light source was just normal white light (which contains a lot of different wavelengths), this time around we used an optical filter so that only light with a wavelength of around 470nm could pass through, which resulted in a blue light shining down on the plates. The light-source itself was a run-of-the-mill flashlight, with a blue light filter installed in front of the lens. To eliminate the effect of temperature gradients inside the incubator, the three samples were placed in a triangle formation in the center of the incubator. <br>
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[[Image:Lightbox5k.gif|210px| Schematic over plate positioning and areas exposed to light.]]
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[[Image:Lightbox5k.gif|210px|thumb|left| Schematic over plate positioning and areas exposed to light.]]
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Another deviation from the protocol is that the culture was inoculated at the center of the plate, instead one colony each was inoculated in the center of the light exposed and dark half respectively. This would give us more information on how the bacteria would behave when directly exposed to either the dark or light surroundings, instead of the gradient that was present in the first experiment.<br>
Another deviation from the protocol is that the culture was inoculated at the center of the plate, instead one colony each was inoculated in the center of the light exposed and dark half respectively. This would give us more information on how the bacteria would behave when directly exposed to either the dark or light surroundings, instead of the gradient that was present in the first experiment.<br>
From the results of the first experiment we expected the culture containing K343007 to spread out in the dark and not to spread when exposed to light. The wildtype bacteria should spread out evenly no matter if exposed to light or not and the non-motile strain (DH5alpha) should not move regardless of the light conditions. Our expectations from the first experiment were fulfilled, as the bacteria behaved exactly as expected. This made it possible to conclude that the photosensor has an effect on the bacteria's tumbling frequency, but if it does in fact reduce the tumbling is not possible to say, since both an increased and reduced tumbling frequency will look alike.<br><br>
From the results of the first experiment we expected the culture containing K343007 to spread out in the dark and not to spread when exposed to light. The wildtype bacteria should spread out evenly no matter if exposed to light or not and the non-motile strain (DH5alpha) should not move regardless of the light conditions. Our expectations from the first experiment were fulfilled, as the bacteria behaved exactly as expected. This made it possible to conclude that the photosensor has an effect on the bacteria's tumbling frequency, but if it does in fact reduce the tumbling is not possible to say, since both an increased and reduced tumbling frequency will look alike.<br><br>
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''From left to right: MG1655 (Wildtype), Photosensor (Bacteria containing K343007), DH5alpha (non-motile strain)
[[Image:Team-SDU-Denmark-MG1655.JPG|210px|MG1655]]  
[[Image:Team-SDU-Denmark-MG1655.JPG|210px|MG1655]]  
[[Image:Team-SDU-Denmark-Photosensor.JPG|210px|Photosensor]]  
[[Image:Team-SDU-Denmark-Photosensor.JPG|210px|Photosensor]]  

Revision as of 03:38, 27 October 2010