Inorganic inclusion bodies:
Polyphosphate granules orMetachromatic granules:
Linear polymer of organo phosphates joined by ester bonds. Reservoirs for phosphate, an important component of cell nucleic acids and also energy reserves. Represents a reserve of inorganic phosphate (polyphosphate) that can be used in the synthesis of ATP. Stain red with certain blue dyes, such as methylene blue, and are collectively known as volutin. Found in algae, fungi and protozoans, as well as bacteria. These granules are quite large and are characteristic of Corynebacterium diphtheriae, the causative agent of diphtheria, thus they have diagnostic significance.
Sulphur granules:
Sulphur bacteria, which belong to the genus Thiobacillus, derive energy by oxidizing sulfur and sulfur containing compounds. These bacteria may deposit sulfur granules in the cell, where they serve as an energy reserve. Purple photosynthetic bacteria use H2S as electron donor and accumulate resulting sulfurin either the periplasmic space or in special cytoplasmic globules.
Magnetosomes:
Not for storage, but these are used by some bacteria to orient in the earth's magnetic field. These inclusion bodies contain iron in the form of magnetite (greigite or pyrite) (Fig. 13). Ex. Aquaspirillum magnetotacticum. Also present in heads of birds, dolphins, and turtles etc which aid in navigation.
Fig. 13. Magnetosomes
Endospores “An escape pod for DNA”
Endospores are a survival mechanism:they are triggered to form during adverse environmental conditions. They are NOT reproductive structures as only one cell gives rise to one spore and endospores can be identified with special stains and differentiated from the vegetative cell (Fig. 14). Endospores are resistant to: heat: withstand boiling for over one hour; desiccation, UV radiation and chemical disinfectants. The resistance of these spores has serious consequence and some very pathogenic bacteria have the ability of produce such spores
Fig. 14. Endospore formation
REFERENCES:
Text Books:
1. Jeffery C. Pommerville. Alcamo's Fundamentals of Microbiology (Tenth Edition). Jones and Bartlett Student edition.
2. Gerard J. Tortora, Berdell R. Funke, Christine L. Case. Pearson - Microbiology: An Introduction. Benjamin Cummings.
Reference Books:
1. Lansing M. Prescott, John P. Harley and Donald A. Klein. Microbiology. Mc Graw Hill companies.