YEAST MOLD PLATES - sterlization (Aug/26/2005 )

In our lab we pour yeast/mold plates for resale. We are having troubles with sterilization in the lab, and keeping these plates from growing in the field. Can anyone give me some tips on how to keep our work area sterile? (We autoclave all our items that we use for pouring, we buy sterile plates, we sanitize the area that we're going to be pouring in, vents are closed off, foot traffic minimized...)
Can someone also tell me why exactly you want to store the plates upside down after they're dry? I understand it's to keep condensation from dripping onto the agar, but is there any other explanation as to why you would do this? Why does that condensation cause growth on the agar?

Thanks!!

Hi I don't know for yeast/mold plates, but for some sensitive bacterial media, the best way to avoid contamination is to pour them under a sterile cabinet. UV are run for at least 20 minutes before use with ventilators running and then plates can be poured safely.

For the upside down conservation, it's not that water cause growth on the plates, it's that having when you have water on the plate bacteria "swim" in it and you cannot see any more individual colonies on it. Plus when you are plating , the less liquid on the surface, the faster it is absorbed into the plate, which makes plating faster and easier.

Hope this help.

Patrick