We are using typical Op50 to feed worms. From the beginning we had a problem with those ,droplets". We were ordering OP50 from CGC and we are using typical media for worms, NGM. Do someone knows what it can be?
It seems likely to be contamination (another bacteria entirely, or I suppose it’s conceivable it’s a mutant derived from OP50). You should always streak out your bacterial food source, and grow a bottle or tube of food from a single colony.
If you did streak it out and pick a single colony, I’d still suggest contamination is the culprit, and that something isn’t properly sterilized.
If you really want to get to the bottom of the problem, you could streak out the bacteria from a plate like the one pictured, and get some 16S sequence from colonies of different morphology. I suspect though that the identity of the contaminant would not be that interesting, it’s more important just to stop seeing it.
Thank you very much for your answer. We did all the things that you said. Now we will send it to sequencing. I was just looking for another solution to get rid of it. Everything is clean. Plate from CGC is always open under the hood. We don’t have any idea from where that came and how to eliminate this.
I don’t understand:
- Why would the plate ever be open, for longer than it takes to get some bacteria off of it?
- What purpose is the hood serving? A reasonably clean bench should be fine.
- Why are you doing much of anything with the plate from the CGC? As soon as it arrives you should use it to make frozen stocks and streak out its bacteria for single colonies, which should then be used to seed plates for worms and also to make additional frozen stocks. There should be little or no reason to return to the original plate.
We were doing like you said. On bench, fire around but those droplets were appearing thats why we decided to keep everything as clean as possible
Have you tried replicating the entire process, start to finish, except instead of inoculating the growth media from a single streaked colony of OP50 you don’t inoculate it at all? See if you still get these scattered large colonies?
Also, are the colonies restricted to the bacterial lawn?