Contamination or not? - Cell Culture Contamination (Nov/07/2007 )
Hey there,
I was wondering how you can tell if a contaminant is actually a contaminant and not cell debris/etc. I have HEK-A2b cells which have "black spot"-like "contaminants" in the dishes. The spots are large (the size of the cells or larger, so not bacteria, at least not individual backteria), appear to be immotile, and do not seem to grow over time. However, they do not go away either, despite filter-sterilizing the media, replacing the media in all dishes, and rinsing dishes with HBSS inbetween removal of old media and putting in filtered media. They look irreular in shape, almost like a mass of smaller parts, and very dark. Anyone know what I might be looking at? How do I know if it's cell parts or something else innocent? Also, the "black spots" occur in test media dishes (dishes with JUST media) as well as cell dishes DESPITE filtering the media, so it makes me wonder if they might be something that can be passed in the incubator or somehow staying in the media despite filtering.
Anyhow, any ideas as to what it is/how to get rid of it would be much appreciated 
Thanks,
Christie
I was wondering how you can tell if a contaminant is actually a contaminant and not cell debris/etc. I have HEK-A2b cells which have "black spot"-like "contaminants" in the dishes. The spots are large (the size of the cells or larger, so not bacteria, at least not individual backteria), appear to be immotile, and do not seem to grow over time. However, they do not go away either, despite filter-sterilizing the media, replacing the media in all dishes, and rinsing dishes with HBSS inbetween removal of old media and putting in filtered media. They look irreular in shape, almost like a mass of smaller parts, and very dark. Anyone know what I might be looking at? How do I know if it's cell parts or something else innocent? Also, the "black spots" occur in test media dishes (dishes with JUST media) as well as cell dishes DESPITE filtering the media, so it makes me wonder if they might be something that can be passed in the incubator or somehow staying in the media despite filtering.
Anyhow, any ideas as to what it is/how to get rid of it would be much appreciated
Thanks,
Christie
Dear Christie,
We really need to see pictures of the debris you are trying to describe. They maybe protein crystals that form from the FBS/FCS. Normally if they are Fungal, the amount of debris increases with time. It is definitely not bacteria if the black spots are the size of cells.
In normal culture cells will die and turn into "ghost cells" which are the same size if not bigger than normal cells. However these ghost's can be easily filtered through a "sterilising" 0.2uM filter. Also some cell lines can produce debris over time in culture i.e. Caco 2 and DLD-1 cells.
Hope this is useful, please put some phase contrast images on this site for us to see.
Kindest regards
Rhombus