re-growing and preparing for on/off

Yesterday and today with Maarten de Smit we’ve prepared an experiment that we can do tomorrow, and see if we can really turn the glow in the bacteria on and off – thus creating a bio-pixel.

Meanwhile, Jos Arents at the University of Amsterdam as preparing the first plates with the bacteria that could have the same effect – but triggered by light. He’ll have the plates grow out hopefully tomorrow as well.

Here at Leiden University, we’ve prepared two different kinds of environments for the bacteria, based on earlier results. The major difference is that one has a lot more arabinose in it, which is the ingredient that triggers the DNA added to the bacteria to produce fluorescent proteins.

This was done as it turned out that the Wilks article mentions two orders of magnitude less arabinose than what we’ve used in the BIO-RAD kit (31μg/ml vs. 4800μg/ml). And the latter was glowing way brighter.

So the resulting plates contained the following at the end:

carbenicillin arabinose
low arabinose plate base 50μg/ml 31μg/ml
high arabinose plate base 50μg/ml 4800μg/ml
low arabinose plate lawn 50μg/ml 390μg/ml
high arabinose plate lawn 50μg/ml 6200μg/ml


Also, we’ve prepared bacteria lawns – that is, not bacteria that grow out in separate colonies, but bacteria that would grow in a uniform manner, and thus create a layer filled with bacteria. How this is done is that we’ve put bacteria in a liquid LB base yesterday, and have it grow there for a day at 37°C. After that, the liquid LB with lots of bacteria was mixed with LB containing all the goodies (see above) and agarose, so that it will solidify. And the whole thing was poured over a regular LB agarose plate.

Additionally, we’ve prepared some pGLO colonies on high arabinose plates, so as to see if they will glow as brightly as the original results of the BIO-RAD Kit experiment.

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