Clumping and contamination in cell culture - (Apr/17/2008 )
I am currently growing U937 suspension cells. Recently, I noticed that my cells clump while growing. It never happen before. When I observed under the microscope, I can see that some vibrating dots, smaller size than my cells. Some of these dots seemed to be attached to the cells and some of it clumped together. I tried plating the clumping culture on LB agar and some yellowish colonies grew. Could it be mycoplasma contamination? Or is other microbes or fungus? I am very worry as now when I tried growing new vials, I can observed the same thing. Can anyone help me urgently? Thank you!
I'm unfamiliar with culture contaminations like this, but, if you plate another cell type onto ager, grown in the same incubator, do similar colonies grow? I believe there are test kits for mycoplasma. If it is bacterial, the media should become cloudy soon, and it will be obvious that something is terribly wrong. I am unsure what a fungal infection looks like, though. Maybe you will have to go to some lower passage cells, and hopefully this does not happen.
I did see that in my HeLa culture: the cell culture growth was arrested and they die within one day upon plating. Practically, this can't be mycoplasma, since you should not be able to see it due to extremely small size of the colony, recognizable only in the electrone microscope (from what I read). The only way to do the check is perhaps the PCR test. The interesting thing is that these grew despite the antibiotics added to the growth media. In my case it was easy - I just renewed the culture.