Satellite colonies in pGLO E. coli culture

[darylc123]

Hi,

I am planning to conduct an experiment involving satellite colonies. The experiment is based off the pGLO transformation lab that inserts an ampicillin resistance gene, araC, and GFP gene into E. coli. Once grown in LB/amp/ara culture, the transformed E. coli secrete beta lactamase, which breaks down the surrounding ampicillin and allows non-transformed "satellite" bacteria to grow around it.

I'm having some trouble coming up with a suitable experiment to research the satellites. So far my ideas are to investigate the correlation between the ampicillin concentration and number/amount of satellite colonies. So if the ampicillin is increased, the number of satellites should go down. But how would I measure the satellites? Should I count them, measure the radius of the whole colony, or test for the presence of beta lactamase?

If you have any ideas, please help! Thanks!

[JackBean]

And do you need to measure them? Isn't just "present/absent" good enough?

[darylc123]

They're present at all concentrations.

[JackBean]

Well, than I don't understand the principle :-/

[BEKK]

In my grade 12 biology class we just did a lab consisting of DNA strands with the ampicillin resistence and the green gene. We saw after our procedure that there were colonies of E. coli which were green, and then little satellites around them that were NOT green. This would show you that they the satellites were not transformed. Also, after the first few days sitting at room temp we didn't find many satellite colonies and we could barely see them, but after being in the incubator for 24 hours we could clearly see them. Not sure if this will help...but if you want the procedure let me know