checking on GFP expression

Following up on yesterday’s results, we came up with an experiment plan to see how the GFP expression is turned on by the addition of arabinose to the bacteria. What we want to investigate is:

  • in what stage of bacteria growth does the arabinose have the most effect
  • what amount of arabinose is needed
  • what starting amount of bacteria yields the best results

All this in the context of the bacteria being grown inside the agar medium itself, not on top.

Thus we came up with creating the following:

  • LB agar, 20 ml /plate
  • carbenicillin, 50μg/ml concentration
  • bacteria liquid cultures at:
    • 0.55 ml / plate
    • 1.1 ml /plate
    • 2.2 ml / plate

We put these plates into an incubator, and each our we get a different plate, and drop different concentration of arabinose on them, making three 5μl drops each:

  • 1000μg
  • 125μg (1/8 of the original)
  • 15.625μg (1/64 of the original)
  • 1.95μg (1/512 of the original)

So now, every hour we’re taking a set of plates, and dropping different concentrations of arabinose on them. We’re also checking to see of course if last hour’s drops have made any effect already. After the first hour, there was no effect yet. Maybe GFP expression is turned on slower than that…

But then again, we might have killed all the bacteria by mixing them into too hot LB agar (though we could hold it in our hands, so it was surely colder than 50 °C). And we didn’t really dilute the LB agar either.

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