The life time of Luria Broth(LB) media with Ampicillin ?

[Lee Daesang]

Dear netter,

I wonder the life time of Luria Broth( LB ) containg ampicillin (50ug/ml).

Two months age, i made the LB-ampicillin stocks and have stored it in 

cold room ( about 4 ¡£C). At that time it worked good in expressing the 

foreign protein in E. coli as inclusion body, but noedays it doesn't.

I also wonder about the life time of the Ampicillin powder at 4 ¡£C.

If you have any idea about those things, please  dont't hesite to

 write a reply mail.

Thanks in advance.