As you know, mycoplasma can be very hard to deal with. They are resistant to some antibiotics, may be small enough to slip through typical lab filters, and they can linger on surfaces and equipment. Some potential sources of introduction are shared cell lines between labs, contaminated reagents such as serum or natural proteins, or they can even be transmitted by lab personnel. Therefore, it is possible that raw materials could be a source if the supplier isn’t diligent. At R&D Systems, we ensure that any serum used in our manufacturing process is tested free from mycoplasma. In addition, mycoplasma testing is part of our routine process for cell banks and bulk lots used for GMP manufacturing.