Mollicutes (Latin mollis = " soft", cutis = " skin," the soft-skinned ) refers to a class of bacteria. They belong to the phylum Firmicutes usually gram-positive, gram- negative but are themselves because they have no cell wall. They represent the smallest and simplest known organisms, and they live as parasites of other cells. The tiny Mollicutes are seated on or in its host cells and remove many of these compounds that they need to live. Especially in the family of mycoplasma find pathogens. The genome of Mollicutes is very small and can be numerous genes for the synthesis of vital molecules are missing (such as amino acids). This is based - just like the lack of a cell wall - on the adaptation to the parasitic lifestyle.

Representatives of Mollicutes are in research laboratories dreaded contaminants of cell cultures because they can happen due to their small size and flexible cell structure bacteria-proof filter. On average, 30 % of all cell cultures should contain mycoplasmas. The most common contaminants are Mycoplasma hyoorhinis, M. arginii, M. orale and Acholeplasma laidlawaii. The mycoplasma can alter physiological and morphological parameters of the infected cells and thus affect the results of different experiments. Cell cultures must therefore be checked regularly for contamination.


The class includes orders:

  • Mycoplasmatales
  • Entomoplasmatales
  • Acholeplasmatales
  • Anaeroplasmatales