I have been culturing lymphoblastoid cells and have been observing these small, black particles for over a month now.
The particles are smaller than the LCL single cells, they do not move but vibrate slightly. The number of black dots increases as you leave the culture to grow, and the media becomes acidic and turns yellow but no turbidity is observed.
We have tested on chocolate agar (negative), thioglycolate (negative), mycoplasma (negative). Treating the cells with 1% and 3% PenStrep, helped cells proliferate again, but did not remove the particles. We also tried with piperacillin-tazobactam, which also didn't get rid of these particles.
Cell proliferation has ceased although cells appear to form healthy clumps as per their characteristics. We have sterilized our entire cell culture room barring the incubators.
We now think maybe it might be intracellular bacteria, or simply stress particles releasing from the cells. Does anyone have any leads?
Hello Anushka Banerjee
Please refer to the articles below. It may be helpful.
Article Got black swimming dots in your cell culture? Identification...
https://www.biorxiv.org/content/10.1101/366906v1.full
Best.
I have my thoughts, but to confirm, run antibody staining with either CEA-CAM-1 (all species) or CD66e (human). If negative, maybe as Malcolm Nobre postulated. But if positive, then get back to me.
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