Eliminate E.coli from C.elegans stocks

Hi everyone!
I like to remove E.coli OP50 because I am working with other bacterias. I made a gravid synchronized, but it did not work.
I want to know which way is more effective to remove E.coli from C.elegans stocks.

Thanks a lot!

Did you try a bleach / egg prep of those gravid adults and let them hatch into M9 buffer? That usually works. You could try adding antibiotics to that if you think there is residual bacteria.

It could also be ‘slime’ which is not a bacteria and thus is quite hard to get rid of even after bleaching. Many worm strains you receive from other labs (less so from CGC) can be contaminated with slime. It can usually be seen as these little round balls on edges of nearly starved plates. It can also look like trails of bacteria that never seem to go away. It can eventually overgrow the plate and form a hard shell. The worms love it, even though it kills them, so it’s hard to get rid of. I recommend bleaching a gravid adult on the edge of the plate, letting the worms crawl out to the lawn of food, and then moving those L1’s gently to fresh plates every few hours over a couple of days. Alternatively, you can just move the adults until the slime is flushed from their system, but even then it’s hard to really get rid of it.

A tweak from our worm cleaning protocol for your consideration:

  1. Make worm cleaning bleach solution (500 ul):
    H2O 367 ul
    10N NaOH 32.5 ul
    NaOCl (bleach) 100 ul

  2. Transfer 50ul of the bleach solution that was freshly made onto the clean agar area outside of the bacteria lawn of a new passage plate (with whatever bacteria you want to feed the worms with).

  3. Move as many adult worms carrying eggs as possible to the bleach solution drop before it becomes dry (about 5-10 worms).

  4. On the second day, check if worms alive on the new plate. If so, cut the area that once had bleach on it.