Does anybody knows why my worms like digging into the agar? Thank you.

Hi, there,

   As the title, it's a really weird thing that my worms (N2) are keen to dig into the agar, no matter how many food left on the surface. My plates are NGM seeded with OP50. 
   I think there are several possibilities leading to this. But I am not sure whether or not it's true. 
   1. We changed the agar brand recently, and the agar seems softer than before. 
   2. The OP50 we use may be mutate.

   So, If anybody meet the same problem before or know the reason. Please help me. Thank you:)

you may try to increase the agar concentration


it’s worms nature to crawl and dig :slight_smile:
putting aside the mutation & other possibilities, i would give several suggestion on the handling part:

  1. yes, you may increase the agar concentration. 1.7% works fine to us at all time, you may try 3%.
  2. do not let the agar air-dried over long period – the cracking on surface allow worms to burrow.
  3. seed ample OP50 – we always find that the worms starts digging and burrowing when food depleted – since you said there are food left, so this will not be the cause

that’s all i could think of. Good luck

With uncontaminated food and high-quality plates (which I admit I can’t define - it has something to do with sufficiently good agar with a high enough concentration), N2 should often refrain from digging even after it exhausts its food source, at least for a while (CB4856 digs more, possibly because breaks in the agar form at the worm aggregates). I don’t know how much of a contribution to the prevention of burrowing comes from the agar source (I’ve never varied this, but have heard anecdotes claiming it makes a big difference), but I would definitely make sure you’ve cleaned your strains and are using bacteria grown from a single colony. As Tyrael says, you should also avoid cracks (which can happen as plates that are too thin or too old become dry) and avoid breaking the agar with your pick.

switch back to the old agar brand.

if all else fails, 10 mM sodium azide will prevent all future burrowing problems.

Sigma A1296 or bust! Not very cost effective, but it’s lovely.

Agar at a concentration of 20 g/L works very well for our lab to prevent digging problems :slight_smile: We have noticed that if you don’t stir your NGM/Agar straight after it comes out of the autoclave, then some of the agar doesn’t fully dissolve and effectively lowers the concentration. So stir it while it’s still really hot too.

Hi yichangchen,

  1. the tried and tested method described in the Wormbook (methods);

when followed carefully works…EVERY TIME. I have never found it to be problematic in terms of worms digging in, sloppy agar, weird colony growth etc.

  1. We use an agar-agar (Kobe I) from a local distributor and this is also fine…Sigma agar has a fancy price but does not improve on our agar (we tested this).

  2. 17gL-1 agar is all you need, you’re making NGM plates not hockey pucks.

  3. Missing out the cholesterol (you didn’t did you?) would also make the worms dig in.

  4. If you have agar that is visibly weaker then change back. Assuming that it was cost that made you change in the first place, you have more than made up the difference in price by the amount of time you are wasting trying to find out what is wrong.

  5. (for jmg326) If you have undissolved agar at the end of the autoclaving step then either;

(i) your autoclave is not reaching 121 degrees C/1 atm during its cycle, or,

(ii) your cycle is too short, or,

(iii) you dumped your agar in at the start and autoclaved the NGM mix (without stirring for a couple of minutes). Even if this was so, the NGM mix is stirred afterwards during the addition of the cholesterol, Mg etc.


we also use agar agar, one with high gel-strenght. works fine!