I know that beta lactamase produced by the colonies will degrade the ampicillin in vicinity where spurious satellite colonies can grow but how long can unused plates of Luria Bertani Agar media with Ampicillin be stored at 4 degree celsius? Does it spontaneously get degraded at 37? Among commonly used antibiotics like Kanamycin, chloramphenicol which one is more stable?
Well what is reported is that Ampicillin stock solutions are stable at 2-8 degree Celsius for around 3 weeks. If long term storage is needed -20 degree could help. At 37 ampicillin won't last more than 3 days. The stability is also dependent on pH.
https://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/Sigma/Product_Information_Sheet/a0166pis.pdf
Although, we always prefer to use the fresh LB agar plates (not more than 3 days), but it happened that we kept LB-Amp/Carb/Gm plates in 4°C for two weeks at a time, and the antibiotics seem to work still fine.
Dear Tia's,
Can you tell at which step u r really stuck? May be we can help u.
http://www.protocol-online.org/biology-forums/posts/9503.html
This guy seems to have a similar experience to what I have - up to a few months is totally fine. If needed a small amount of extra antibiotic can be added.
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