Field of Science


I came in this morning, all bright and ready for phage propagation (harvesting phages from plates is actually quite fun) and what did we find? All the plates from yesterday were bad. To make a phage plaque you plate out a smooth 'lawn' of bacteria onto an agar plate and then pour phage over it. Where one phage lands it kills and multiplies until it forms a little clear spot or 'plaque' on the plate. (you can't see the phage plaques very well in the picture, but you can see the bacterial lawn)

This morning, all our plates had little fuzzy marks on them. Which is fine, could be phages did the control plate. The control plate had no phage on it at all, it was meant to have just the bacteria but itstead it too had little fuzzy marks.


Without good controls you can't trust your results. At first we thought it was just badly grown host until my supervisor noticed that the tryptone we'd been working with (tryptone broth is one medium that you can grow the bacteria in) was cloudy. Not good. If a substance that is usually clear starts looking cloudy then it means it's got bacteria in it.

Our plates were all contaminated. The fuzzy marks were phage, bad host and/or another bacterial contaminant. Basically we have to do all of yesterdays work all over again today and we need a lot more media (agar for plates, tryptone for bacteria, etc).

Guess who gets to make up all the new media?

I do love working in labs. But it can sometimes be the more frustrating thing on earth. And media pouring is just mindnumbingly boring and faintly awkward. Which is why, of course, the lab rat gets to do it.

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