How can you detect mycoplasma contamination in your cell cultures?
Unfortunately, it is challenging to quickly and reliably detect mycoplasma contamination in cell cultures. One reason is that mycoplasma contamination does not typically trigger the turbidity changes that are common with other types of bacterial or fungal contamination. In addition, the bacteria are too small to observe using optical microscopy without the need for specific labeling.
However, cell cultures can show subtle changes as a result of mycoplasma contamination, meaning careful analysis can provide some insight. For example, as the mycoplasma will compete with your cells for nutrients in the culture medium, one of the first visible signs of contamination is a reduced rate of cell proliferation. Other indications of contamination include cell aggregation, morphological changes, and poor transfection efficiencies (which can be easier to spot when you are working with cells that used to show high transfection efficiencies in the past).
The only way to detect mycoplasma species is to explicitly test for them. There are several different techniques to identify if your cell cultures are contaminated with mycoplasma. These include histochemical staining, ELISA, DNA fluorochrome staining, microbiological culture, biochemical / bioluminescence methods, and PCR. A research group even managed to show the presence of Mycoplasma species by light microscopy using oblique illumination, which renders the mycoplasma cells visible as white foci due to light scattering.
The best mycoplasma assays are highly sensitive and specific, but can also be performed quickly. Based on these criteria, we discuss the most commonly used assays below.
