My lab has quite a puzzle on our hands. We seem to have a bacterial contamination in our cell lines and need to figure out where it is coming from and how to get rid of it. its a lot of information so:
- multiple cell lines infected: PC3, 293, U2OS, etc.
- seems to grows in the presence of pen/strep, zeocin, and gentamicin
- tried treatment with Normocure and if anything they're growing faster
- cleaned out hood, water bath, and all parts of the incubator with ethanol; didn't help
- got new medium, trypsin, and PBS; no luck
- examined the medium (new and old); no sign of bacteria
- cells taken from stock in the liquid nitrogen tank show contamination after 1-2 days when grown in new medium even when grown in a different incubator
- it seemed to begin a few days after adding new (autoclaved) water to the humidifier unit in the incubator
- autoclaved pipette tips sometimes show condensation after being removed from the autoclave
- lab, which only shares our microscopes and autoclave, say they are beginning to show signs of contamination
We are trying to figure out where the contamination is coming from and how to save the cells. The cell lines are mutants and took us quite some time to get them so we really, really don't want to toss them out unless we absolutely must. Any ideas?