I am a new person to this forum and also to the C.elegans filed. I had a problem with the E.Coli OP50. After seeding E.Coli OP50 onto the plates, I found some different spots (or colonies) on the E.Coli lawn (i think that were bacillus).
Therefore, I do not know whether I had problem with E.Coli OP50 stock or there were something contaminated during E.Coli preparation stage.
Does anyone have any ideas for my situation? Now I consider to check whether I have problem with E.Coli stock or not?
In case you aren’t already doing so, you should be inoculating the bacterial culture you use to spot your plates from a single colony, after streaking out your OP50 for the purpose. If you still get contamination or variability from plate to plate, at least you’ll have a better idea of when it happened.
Thank you very much for your suggestion! I am sorry for my late reply! :-[
I received new E.coli OP50 stock from other C.elegans lab (they are using this stock and everything is OK) and made new plates. However, there were just some plates contaminated
with the same condition! (strange spots on the plate). Although I was carefully this time, I don not know the reason.
Now another lab’ member will make new plates with this stock again and I am waiting the result!
When you say “strange spots on the plate”, it’s a bit different from what you said before (“different spots on the lawn”). Are the spots confined to the lawn, or are they beyond the lawn on the surface of the plate? Do you see bacterial inclusions growing within the media (usually disc shaped)?
Basically, the question is whether it’s your plates that are contaminated, or your benchtop, or your bacterial broth. It’s not that hard to tell which is happening, which can tell you exactly where the problem is. But in any case, the solution is the same: double-check you’re using sterile technique, adding properly sterilized solutions to the cooled autoclaved media, using a homogenous bacterial broth to spot the plates, etcetera.
