Autoclaving Media Versus Sterile Filter - (May/07/2008 )

In my old lab the technicians would make up PBS and use the Corning bottle top filters for sterilization. Now that I am setting up my own lab - and considering those filters are rather pricey - I'm wondering if we can just autoclave the media in the bottles. What are the advantages/disadvantages? What do you folks do? Are there certain types of media that autoclaving is ok, but not others? I would assume proteinacious media would not be autoclaveable. Is that correct? Thanks, for any advice.

PBS can be safely autoclaved. It only contains inorganic salts, which are quite heat-stable. AFAIK media can not be autoclaved, because there are many different (organic) compounds in them, which would be lost because of the heating. One way you can save money, is to prepare media from powder, sterile filter large amounts (like 20 l or so) with one bottletop filter and store in 1 l sterile bottles. You have to add (sterile) glutamine and FBS (and whatever else you want) when you open the bottle.

We also use autoclaved PBS for the cell culture. We make a big stock (for ~20 0.5lt glass bottles), fill up 0.5 lt bottles and autoclave it. Then the bottles are kept at 4 C degree.

What I don`t like about it is that one usually sees some kind of dust (I don`t know how to call it) in the bottle. It is not contamination but it looks like growth. It is probably some dust or fibers coming from the stock but makes me a bit nervous every time.

We also autoclave it for use in plant pathology lab.
Good luck!

mdfenko is right. The cap should be loose. The same with all liquid stuff you autoclave in a bottle (plastic and glass). After autoclaving you close it tightly.