Gram-positieve bacteriën: Bacilli en Mycoplasma

The phylum Tenericutes — commonly known as mycoplasmas — includes a single class, Mollicutes. These bacteria lack cell walls and are among the smallest known organisms.

Mycoplasmas often live in close association with animal or plant hosts in diverse environments.

Despite the lack of cell walls, mycoplasma membranes are resistant to osmotic lysis partly due to the presence of sterols and lipoglycans.

Mycoplasmas exhibit pleomorphic forms, with cultures often showing small coccoid cells, large swollen cells, and filamentous forms that may be branched.

Genus Spiroplasma is helical or spiral-shaped. It lacks cell walls and flagella yet exhibits motility through screw-like motion or slow undulations.

Spiroplasma species are found in various places, from the external surfaces of insects and plants to their internal tissues.

One notable species, Spiroplasma citri, causes citrus stubborn disease in citrus plants.

Other species, such as Mycoplasma pneumoniae, Ureaplasma urealyticum, and Metamycoplasma hominis, are pathogenic to humans.