I am observing black dots (as you can see in the empty spaces where there are no cells) in my cell culture as attached in the picture. I think they are motile. The media has not become turbid or changed colour. I am seeing this in MDCK and HEK cells. Is it contamination?
Hello Sharmada Swaminath
It has been proposed that these black swimming dots are non-living inorganic nanoparticles yet should be derived from an unidentified pathogen which should have the following characteristics: airborne transmitted; cell-dependent; insensitive to antibiotics; filterable through 0.1 μm membrane.
This needs to be further investigated.
You can refer to the article below for more information on this.
https://www.biorxiv.org/content/10.1101/366906v1.full
You can also refer to the article below.
Article Got black swimming dots in your cell culture? Identification...
Best Wishes.
Hello Sharmada
The black swimming dots could be anything from cell debris (organic leftovers of dying or dead cells) to microbes. Since you say they are motile, observe these particles carefully. See if you are facing any issues with cell growth. From the pictures that you have shared, they don't look like microbes. Most probably, they are cell debris or black dots (their source is still unknown).
Also, since you say that the media hasn't turned turbid, chances of contamination is less. Keep an eye on growth of cells. If the growth is normal, then you should not be worried about these black particles.
Thank you Abu Sufiyan Chhipa !!! The growth of the cells were normal neither did the color of the media change.
You should also check for mycoplasma contamination. The fact that the cytoplasm of your cells is grainy could indicate intracellular infection.
@Sharmada Swaminath This is very common in cell culture, no need to worry as it does not affects growth of cells. These granules can be seen because of cellular debris( small vibrating particles around the periphery of cell) and cellular secretions which usually get washed off with 1X DPBS, so if its bothering you then proceed with a wash of 1XDPBS (although not really required).
These are actually not normal and may require the use of gentamycin to remove them. Please fix the cells and stain with DAPI to see if your cells are contaminated or not, it will be very helpful to perform this screen as you will be sure to perform your experiments on good healthy cells.
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