Mycoplasma General Account

Mycoplasma is the smallest organism without having cellwall

1. Presented To- Pro. HK Kehri Faculty of Botany University of Allahabad Presented by- Salman khan MSc-3 rd SEM Topic- General Account of Mycoplasma

2. Mycoplasmas are the smallest, and unicellular prokaryotes belonging to class-Mollicutes. Mycoplasma have no cell wall that is they are pleomorphic. It is sensitive to osmotic shock / detergents. They are also sensitive to antibiotics such as tetracyclin chloramphenicol. They are smallest bacteria that the capability of autonomous growth. They are gram positive bacteria. Mycoplasma are the facultative anaerobes or obligatory anaerobes. They have low G+C percent that is about 23-41%. Introduction of Mycoplasma: -

3. History of Mycoplasma:- Discovered by Pasture in 1843. Isolated from pleural fluid of cattle. It was called as Mycoplasma mycoides. Nocard and Roux first cultured Mycoplasma in 1898. In 1929 Nowak called them PPLO.

4. They are unicellular, smallest, non-motile and prokaryotic organisms forming fried egg-shaped colonies. They may be rod like, ring like, globoid or filamentous. The filaments are of uniform diameter (100-300 nm) and vary in length from 3 nm to 150 nm. Some mycoplasma predominantly assumes spherical shape (300-800 nm in diameter). Morphology of Mycoplasma:-

5. Chemical composition of Mycoplasma: - Composition Percentage (%) Protein 40-60% Carbohydrate 0-1% DNA content 3-7% Lipid 8-10%

6. Structure of Mycoplasma: - The cells are small, and the diameter of the cells range between 0.3 and 0.9 µm. These are prokaryotic and do not contain a true nucleus. Each cell is covered with a unit lipoprotein cytoplasmic membrane which is 7.5 – 10 µm thick. The cytoplasm contains genetic material (nucleoplasm like material) and ribosomes. Both DNA and RNA act as genetic materials. It is usually half that usually occurs in other prokaryotes. The DNA amounts to 4 per cent and RNA about 8 per cent. Mycoplasmas are non-motile but show gliding slow movements.

7. Structure:-

8. Reproduction of Mycoplasma: - Mycoplasmas reproduce by budding and or by binary fission. Cells of mycoplasmas divide unevenly into very minute bodies or minimal reproductive unit. These are formed inside the large body or mature cell Their size varies from 330 nm to 450 nm. These bodies are the smallest independent living entities so far known.

9. Transmission: - Mycoplasma like organisms (MLO) or phytoplasmas are usually present in phloem of the host plants and are transmitted from host to another host by leaf hoppers but some are transmitted by psyllids, treehoppers, plant hoppers and some possibly by aphids and miles.