Chromobacteria

Ok. I think I've got the whole idea figured out. Certain opportunistic bacteria species can sense the size of their population, such that they only produce pathogenic agents when there are enough bacterial cells. This communication is facilitated in the bacteria we were using by the AHL signaling molecule. The bacteria can then produce exoproteases in a coordinated manner.

We genetically modify the bacteria such that they also produce an enzyme which destroys the AHL signaling molecule. This causes the bacteria to become unable to communicate and produce the exoproteases. We then test for the presence of these exoproteases by using C. elegans, a kind of tiny worm thingy/nematode.

Because the exoproteases are present in the wild species, the nematodes die as they slowly get digested by the exoproteases. In the modified species, because the AHL they produce are immediately destroyed by the enzyme, the cannot communicate and don't produce the exoproteases. So the nematodes don't die.

The first part of the morning was spent preparing these biosensor arrays. It was meant to prove that the AHL signaling molecule is diffusible. So we used Chromobacteria to test for the presence of AHL. These bacteria produce a visible purple pigment when they detect AHL. So we cut the agar into strips, put the AHL producing bacteria at one end, and dotting the Chromobacteria on the entire length of the strip, to see how far AHL can diffuse. We compared both the wild and modified species of the AHL producing bacteria, in varying amounts. 

Then after that we did DNA purification to prepare the plasmids for calcium chloride induction (heat-shock), as an alternate method of genetic modification instead of the tri-parent induction. Its a rather long process, involving lots of centrifuging and filtering funnels. These are like tiny funnels that fit inside a microfuge tube. It uses a kind of foam polymer as the filter.

Then was lunch. This time I had lunch with Daryl... It was interesting, we talked about a lot of stuff :)

After lunch we did the calcium chloride induction. It took quite a while. Anyhow, the people from bench 1 were like racing the people from my bench for like the whole day. So they cheong all their purification and heat-shock procedures.... Anyway, they won because I was working with 6 people, and they had only 4 people, and we have to wait for everyone to pipette the reagents before we centrifuge all the tubes together..... Lolz....

We spent the in between time talking (alot :) ) to people. There were like these incubation or water bath time that are like 30 min and 45 min... XD So nothing to do just talk..... XD

Then went home.