Mycoplasma contamination of cell cultures has been a concern for decades. Contamination is often not visually apparent, and antibiotics commonly used in tissue culture are ineffective against the bacterium. A study of cell samples used in gene-expression experiments during 2012 and 2013 examined the cells’ RNA sequence data for Mycoplasma DNA sequences. Of the over 9,000 samples studied, 11% were contaminated. Researchers found that expression levels of 61 genes in one of their datasets were affected by the bacterium. These results point to the high cost of contamination, consuming time and resources as experiments need to be repeated. One of the study’s authors estimated one-third of his lab expenses are for tissue culture. The bacterium is typically introduced by researchers or by sharing cell lines, but cell lines from official suppliers have not been found to be infected. Researchers are encouraged to obtain cells from these suppliers and to test their cultures for contamination.

Source: Nature