I am stuck in trouble while pouring LB agar onto my petri dishes. I had to add kanamycin to my plates just before it started to solidify, out of forgetfulness, which I tried to mix using the tip. The plate was such a disaster! Is there a way to melt the agar in the plate and re-solidify it evenly.
I use falcon sterile plastic petri dish.


1 Answer 1


Yes. It is quite simple actually. Do this inside a clean laminar hood:

  • Take a clean sterile scalpel blade or any other sterile long object. 1ml pipette tip would also do.
  • Cut the agar on your plate. Scrape off cleanly.
  • Put it in a sterile glass bottle.
  • Heat in microwave
  • Add kanamycin
  • Pour back

Another solution is to coat the agar surface with kanamycin just like spread plating. Check the appropriate concentrations.

  • $\begingroup$ If the agar has solidified with a nice surface, I would prefer the spreading technique. Works pretty nice and is definitely much less hassle (and contains less contamination problems) than removing and remelting. Before spreading, dry the plates open so they can take up the liquid. $\endgroup$
    – Chris
    Jul 23, 2014 at 15:51

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