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Shelf life of ampicillin in LB media?


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6 replies to this topic

#1 sagar

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Posted 10 March 2009 - 10:18 AM

we generally streak in ampicillin plate and keep it in incubator for overnight ie 15 hrs.does ampicillin degrade in the plate within that period of time?

#2 tuhin_genes

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Posted 10 March 2009 - 10:23 AM

we generally streak in ampicillin plate and keep it in incubator for overnight ie 15 hrs.does ampicillin degrade in the plate within that period of time?

hi sagar,
i am pretty sure ampicillin plates do not degrade overnight...for that reason we can effeciently carry out transformation.well things do not turn up good all the time. I can safely comment that it does not get degraded overnight.

Edited by tuhin_genes, 10 March 2009 - 10:25 AM.

tuhin k guha

#3 klinmed

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Posted 10 March 2009 - 10:44 AM

Amp should be stable overnight at 37 oC . However, colonies of resistant bugs can secrete beta-lactamase into the agar medium. Thus there will be an area around a resistant colony with little, if any, active amp. This can often be seen on transformation plates as small satellite colonies of non-resistant bugs circling a large resistant colony.

#4 tuhin_genes

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Posted 10 March 2009 - 10:56 AM

Amp should be stable overnight at 37 oC . However, colonies of resistant bugs can secrete beta-lactamase into the agar medium. Thus there will be an area around a resistant colony with little, if any, active amp. This can often be seen on transformation plates as small satellite colonies of non-resistant bugs circling a large resistant colony.

ya thats a nice answer to that. good
tuhin k guha

#5 sagar

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Posted 11 March 2009 - 01:44 AM

Amp should be stable overnight at 37 oC . However, colonies of resistant bugs can secrete beta-lactamase into the agar medium. Thus there will be an area around a resistant colony with little, if any, active amp. This can often be seen on transformation plates as small satellite colonies of non-resistant bugs circling a large resistant colony.

yah thanks.
logic is good.may be for that reason we get sometimes false colonies.

#6 isbow

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Posted 16 March 2009 - 04:19 AM

Hi!

I kept my Amp plates for almost 1 month at 4C and they stayed selective. Also incubation for more then 2 days at 30C did not influence selectivity so the antibiotic should be ok. Some papers say that you should not keep these plates for more than one week but from my experience they still work if you store them at 4C. Good luck!

#7 Replica

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Posted 16 March 2009 - 11:54 AM

As for me, I make new plates once in a few months and store them at -4C - and when I finally use it, Amp works perfectly. Never had a single problem with that.
I observed these little sattelite colonies klinmed had mentioned before, but it took them about a week to grow. One night at 37C is safe.
If you actually have troubles with selectivity, than perhapse you should increase Amp concentration.
Double Trouble




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