MYCOPLASMA

Mycoplasma are pleuro pneumonia like organism (PPLO) discovered by Nocard and Roux(1989). They were first isolated from bovine sheep suffering from pleuropneumonia. Originally Mycoplasma were included among bacteria and placed in the class Schizomycetes. But now they have been separated from bacteria and placed in separate class having following systematic position.

Class :Mollicutes
Order :Mycoplasmatales
Family :Mycoplasmatacae
Genus :Mycoplasma

Characteristics

1. They are bacteria without cell wall and are immotile.
2. They are called "Joker of the microbial world".
3. They require sterol [cholesterol] for growth in the culture medium.
4. They can be killed only by certain antibiotics like Tetracycline.
5. They are the smallest known cellular organisms with an average 0.1-0.15 micrometer.
6. They are completely insensitive to enzymes.
7. They reproduce by binary fission only.
   In plants they cause "Little leaf of brinjal" disease.
   In animals they cause Pleuropneumonia.In man they cause Human Infertility and abortions due to infection in the urinogenital tract

A well defined cell wall is lacking in Mycoplasma ,so a three layered plasma membrane forms the outer boundary of the cell. They lack organised nucleus , plasmids, lysosomes, endoplasmic reticulam, mitochondria, golgy complex, centriole, flagella. The genetic material is represented by single DNA duplex which is naked because of the absence of the histone association. DNA lies coiled throughout the cytoplasm. Ribosome is 70s type. Enzymes lies both freely in the cytoplasm as well as associated with the plasma membrane.