Index of Typical Cell Culture ContaminantsTrouble-shooting Guide: If you have a contamination problem, select what you believe to be the organism from the short descriptions below and click on the image to go to a more detailed page.
Bacterial contamination is usually manifest by a sudden change in pH, cloudiness in the medium, sometimes with a slight whiteish film on the cell surface of plates, dishes, or on the bottom of bottles of medium that typically dissipates when the vessel is moved. Under low power (100x) spaces between cells will appear granular or you may see very small black dots. In some cases under higher magnification (400x) cocci or “rods” may be distinguished and there may be motibility of the bacteria.
Bacteria can usually be distinguished from media components such as serum protein by the regular particulate morphology of the organism versus an irregular shape in the case of serum protein cryoprecipitates.
Mycoplasmas cannot be detected by the naked eye or even by typical light microscopy. Therefore, mycoplasma contamination must be detected by alternative testing methods. The image provided here is of a mycoplasma “colony” after being propagated on special agar. The colony has a typical “fried egg” appearance.