Zahra Masoumalinejad - Dept. of Microbiology, Sirjan Branch, Islamic Azad University, Sirjan, Iran
Mohammad Reza Zinatizadeh - Dept. of Genetics, Faculty of Science, Tonekabon Branch, Islamic Azad University, Mazandaran, Iran
Najmeh Tahmasebiabdar - Dept. of Microbiology, Sirjan Branch, Islamic Azad University, Sirjan, Iran

Mycoplasma are small, cell-free bacteria enclosed by a membrane. These bacteria belong to the class of Mollicutes, the order of Mycoplasma tales, and the genus of Mycoplasma. There are more than ۱۰۰ identified species of mycoplasma. The ratio of cytosine to guanine in its DNA is ۲۳–۴۰% and its genome size is ۱۳۵۰–۶۰۰ kb. Mycoplasma require cholesterol to grow, and the temperature suitable for the growth of this bacteria is ۳۷°C. Mycoplasma cause contamination and infections in humans and animals. Some mycoplasma species are seen only in animals. In general, mycoplasma are colonized at the surface of the mucus, and most species are non-invasive. Five main species of mycoplasma have been identified in laboratory mice, including: M.arthritidis, M.collis, M.muris, M.neurolyticum, and M.pulmonis. These species generally require protein-rich environments that contain ۱۰–۱۵% of the animal's serum, and their growth requires nicotinamide adenine nucleotide (NAD), which is commonly used to cultivate mycoplasma in mice. Laboratory research has found that mycoplasmas contamination has an adverse effect on animals. Therefore, it is important that health monitoring programs are implemented as a quality control for animals used in laboratory research.

Mycoplasma, Arthritidis, Muris, Neurolyticum, Pulmonis