autoclave time - (Mar/15/2010 )

Hi,
In the textbook, it usually requires to autoclave medium 15 min, 15psi, 120 degrees.

While I think it depends on the volume of medium autoclaved. But what is the boundary for the time? If the bottle or flask contains only 1/3 volume medium, we can just autoclave 15min, is that right? How about 1/2 volume medium?

Thank you very much!

I would personally suggest you to read through the concept of autoclave.
The pressure 15psi, 121C and 15 minutes is needed to destroy all the living organism (with the exception of strain 121). It doesn't matter if you are half bottle full or full bottle.

just do add to adrians post: depends on the volume of medium. if autoclaving more than 3L in one bottle we increase the time to 20-30 minutes to ensure that the whole liquid is at 121°C for at least 15 min.....you can call it overcautious, but we get less contaminations with this tactic

Well is there such a thing as over-autoclaving? Sometimes i leave my agar for an extra 5 or 10 mins...just to be sure

Yes, you can over-autoclave and "caramelize" your media. I don't think an extra 5 or 10 minutes would matter.