storage of media with antibiotics at 4C.... - (Jan/04/2007 )

Is it ok to store LB for example with kanamycin inside at 4C? it takes some time to thaw antibiotic every time you need to culture.

i do it all the time, but i usually use up a 500mL bottle in less than a week. from what other people do, it seems ok to store it at 4'c for a couple of months ( )

V

I don't know about a couple of months... but I have stored LB+ antibiotics at 4 celsius for a couple of weeks (3wks) and that was fine.

It sounds OK to keep medium with antibiotics in the fridge few weeks.
If you have any doubt, inoculate non transformed bacteria in medium plus antibiotic and you will see that they do not grow.

i have never try this before, but isn't this going to affect their conformation since antibiotics are proteins ....i mean freezing-thawing..

We used to have a thawed aliquot of ampicillin or kanamycin in 4C till its used up. This way the LB with the antibiotic (ususllay for maxi's) is usually made fresh everytime.

But I make up small quantitites of LB with anitbiotics and store in 4C for a few weeks without problem.

We store LB + antibiotics at 4C for at least two months with no problems. Note that tetracycline, erythromycin and rifampicin are light sensitive, and should be stored in the dark. Most antibiotics are not proteins.

here in the lab we store antibiotics at -20C and thaw and freeze them many times. so i was thinking it will be better actually if i do freeze thaw them not from -20C but from 4C.