Microphotograph series of growing microcultures of different strains of PPLOs, L-form bacteria and, as a control, a Micrococcus species (dividing by binary fission) have been presented. Additionally, electron microscopic studies have been performed. Phylogeny
Previously, Mycoplasma species (often commonly called "mycoplasmas", now classified as Mollicutes) were sometimes considered stable L-form bacteria or even viruses, but phylogenetic analysis has identified them as bacteria that have lost their cell walls in the course of evolution.The genus Mycoplasma as originally described is highly paraphyletic, as such it was redescibed by Gupta et al. 2018 and its emendation was accompanied by the removal of 78 species. The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI)
Unassigned species:

Laboratory contaminant
Mycoplasma species are often found in research laboratories as contaminants in cell culture. Mycoplasmal cell culture contamination occurs due to contamination from individuals or contaminated cell culture medium ingredients. Mycoplasma cells are physically small – less than 1  µm, so are difficult to detect with a conventional microscope.Mycoplasmae may induce cellular changes, including chromosome aberrations, changes in metabolism and cell growth. Severe Mycoplasma infections may destroy a cell line. Detection techniques include DNA probe, enzyme immunoassays, PCR, plating on sensitive agar and staining with a DNA stain including DAPI or Hoechst.An estimated 11 to 15% of U.S. laboratory cell cultures are contaminated with mycoplasma. A Corning study showed that half of U.S. scientists did not test for Mycoplasma contamination in their cell cultures.
They have been found in the pleural cavities of cattle suffering from pleuropneumonia. These organisms are often called MLO (mycoplasma-like organisms) or, formerly, PPLO (pleuropneumonia-like organisms). Important characteristics of Mycoplasma species
Cell wall is absent and plasma membrane forms the outer boundary of the cell. Due to the absence of cell walls these organisms can change their shape and are pleomorphic. Lack of nucleus and other membrane-bound organelles. Genetic material is a single DNA duplex and is naked. Ribosomes are 70S type. Possess a replicating disc at one end which assists replication process and also the separation of the genetic materials. Heterotrophic nutrition. Some live as saprophytes but the majority are parasites of plants and animals. The parasitic nature is due to the inability of mycoplasmal bacteria to synthesise the required growth factor. Cell and colony morphology
Due to the lack of a rigid cell wall, Mycoplasma species (like all Mollicutes)  can contort into a broad range of shapes, from round to oblong. They are pleomorphic and therefore cannot be identified as rods, cocci or spirochetes.Colonies show the typical „fried egg” appearance (about 0.5 mm in diameter). Reproduction
In 1954, using phase-contrast microscopy, continual observations of live cells have shown that Mycoplasma species ("mycoplasmas", formerly called pleuropneumonia-like organisms, PPLO, now classified as Mollicutes) and L-form bacteria (previously also called L-phase bacteria) do not proliferate by binary fission, but by a uni- or multi-polar budding mechanism.