I am hoping someone can shed some light on this matter, as I am new at this:
I poured some NGM + carb plates and not long after, the entire plate had crystals all through it (visible to the naked eye). Are these still usable? And, any ideas on how to prevent this in the future?
Thanks.
In general, crystals in NGM are likely to be phosphate salts precipitating out. This problem seems to be exacerbated by use of low-grade chemicals and definitely also by addition of the phosphate buffer when the media is too warm. If the crystals form only in the carb plates and not in regular NGM, I am not sure what it might be.
In my experience, the crystals will not kill the worms. I would not use these plates for generating data, however.
I find that solutions that have been re-autoclaved many many times tend to lead to plates that have lots of crystals in them. I agree that the chances of crystal formation is increased if you add the solutions when the media is too hot.
From my experience as well, the crystals will not kill the worms and the plates are still usable.
Thanks for the insight!
Also, did you use too high carb concentration by mistake perchance?
That would also cause crystals.
Crystals are generally calcium phosphate. They will frequently form at low level regardless, but we’ve found that we can mitigate this by giving the NG agar a good swirl between addition of each salt post autoclaving. I think that without swirling, one can get large local increases in salt concentration, and thus precipitation.
PS I concur that crystals don’t affect worm growth. For most applications they are no problem at all.