Structure of Mesosome in Bacteria

Structure of Mesosome:

The mesosome arises as an investigation of the plasmalemma and may become quite a complex whorl of convoluted membranes. The structure of mesosomes is a matter of conjecture. It is believed that mesosomes are active in cell wall synthesis and in the secretion of extracellular substances. It has been shown that transforming DNA taken up by whole cells of Bacillus Subtilis apparently enters the cell via the mesosomes. There is considerable evidence that the bacterial nuclear body is attached to a mesosome.

A few bacteria have been shown to have another granular inclusion, volutin. It is an inorganic metaphosphate related to ribonucleic acid in the cytoplasm and some of the larger sulfur-oxidizing bacteria contain sulfur. The cytoplasm contains many types of inclusions:

1. Vacuoles: The vacuoles may or may not be present. It depends upon the physiological state of the cell. The vacuoles if present remain surrounded by a membrane. It may contain cell sap, volutin, or sometimes lipid and sulfur.

2. Liquid Globules: The droplets of liquid occur as refractile globules. Sometimes it constitutes 25% of the total weight.

3. Metachromatic Granules: They are also known as ‘volutin granules’. They occur widely in the cytoplasm. They occur in about 40% volume of the cell. They are composed of polymetaphosphate and increase in number towards late in their growth.

4. Glycogen Granules: The glycogen and other polysaccharide granules occur in some forms towards the polar region of the cell.

5. Mitochondria: The mitochondria have been recorded from Mycobacterium, Streptomyces, and others in the form of lamellated structures. They have been found to be centers of oxidation and reduction.

6. Chromatophores: The chromatophore have been reported from the cells of autotrophic bacteria. These photosynthetic pigments are certainly different from those of higher plants.