Cell Culture FAQ: Sources of Mycoplasma - Where do they come from?

This article was published first in "Inside Cell Culture" , the monthly newsletter for cell culture professionals. Find more interesting articles about CO₂ incubators on our page "FAQs and material on CO₂ incubators" .

A frequent source of this invisible plague are previously contaminated cultures that are used in the same laboratory. When a new cell line from an outside source arrives, it should be quarantined until the absence of mycoplasma and any other type of contaminant is proven.
Mycoplasma can be transferred from infected reagents via aerosols which are created when pipetting warm liquids. Using filter tips and working with one cell line at a time in the biosafety cabinet reduces the risk of spreading the contamination throughout the cell culture laboratory.

A major source of mycoplasma are the people working with the cells. One of the most predominant mycoplasma species isolated from cell cultures is Mycoplasma orale, which is commonly found colonizing the human oral cavity and oropharynx. By sneezing, coughing and talking, mycoplasma can find their way into our cell cultures. Therefore, avoid speaking when sitting at the cleanbench or standing in front of the open incubator and strictly follow recomendations for aseptic techniques.

As mycoplasma are very small and flexible due to their lack of a cell wall, they are able to penetrate membrane filters used for sterilization of cell culture media, sera, and other reagents, especially when filtering under pressure conditions. Furthermore, mycoplasma are able to survive in a dried state for several days and can easily be transferred in the shape of aerosols and particles. In case of an acute mycoplasma contamination in the laboratory, you should consider all surfaces, personal protective equipment and lab equipment as potentially contaminated and take strict disinfection measures.