mycoplasmas A group of eubacteria that lack a rigid cell wall and are among the smallest of all living cells (diameter 0.1 μm–0.8 μm). They are either saprotrophic or parasitic and are found on animal mucous and synovial membranes, in insects, and in plants (in which they seem to inhabit sieve tubes). They cause a variety of diseases, including pleuropneumonia in cattle – hence they were formerly known as pleuropneumonia-like organisms (PPLO). Due to their small size and flexible cell wall they can pass through a 0.2-μm-diameter filter and they represent a major contaminant of biotechnological products, such as monoclonal antibodies and vaccines, and of other cell cultures, in which they may exist symbiotically with the cells. Eight genera have been described (including Mycoplasma) with over 120 species. Some authorities place them in the phylum Aphragmabacteria.

mycoplasmas
1. Bacteria of the class Mollicutes
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2. Bacteria of the genus Mycoplasma.