penicillin/streptomycin in cell culture - (Jul/23/2013 )

Hi
Does penicillin/ strepromycin go off after some time after being using to prepare cell culture media and stored in the fridge/ used at 37 every now and then?
I will be grateful for your help
Angelika

Yes it degrades over time.

Thank you. After how much time does it need to be replaced?

The period is dependent on the time at room temp/37 and light exposure.

In most instances (exceptions are selection for an introduced marker and primary cultures), you shouldn't need antibiotics in your cultures if your sterile technique is adequate.