Endospore
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Bacterial spores are dormant, resistant structures formed by certain bacteria under stressful conditions. They have a thick coat that allows them to survive extreme heat, lack of water, toxins, and radiation. There are two types of spore formation: endospores form inside the parent cell while exospores bud off externally. Endospores contain dipicolinic acid which makes them highly resistant. Germination occurs in three stages - activation by damage to the coat, initiation by effectors in a rich environment, and outgrowth involving degradation of spore layers and emergence of a new vegetative cell.
Endospore
- 1. Dr. B. Lal Institute of Biotechnology Bacterial spores By :- Mumal Kanwar Mertiya From :- b.sc. Biotech part 1st Teacher in-charge :- Miss Rinki Sharma Ma’am
- 2. Contents:- *Definition *Structure *Formation * Germination of bacterial spores..
- 3. What is bacterial spores…? Bacterial spores are the dormant forms of bacterial structure which are thick walled , highly refractile and resistant.
- 4. Spore structure : Spore formation is a means by which some bacteria haulting their vegetative phases produces structure that are able to survive in extremely harsh environmental conditions.
- 5. Shapes • Spherical , oval or elongated in shape. • May be narrower or broader(bulge) than parent cell. (1) (2)
- 6. Bacterial spores undergoes two types of formation :- Bacterial spores Endospore Exospore
- 7. o Endospore; Endospores are highly durable dehydrated cells, which can survive extreme heat, lack of water, freezing and exposure to many toxic chemicals and radiation. Endospores also called as “resting cells”. Formed outside the vegetative cell by budding at one end of the cell. Formed inside the parent vegetative cell. The Exospore do not contain dipicolinic acid. They can resist desiccation and heat. o Exospore ;
- 8. Formation : Exospores are formed external to the vegetative cell by budding at one end of the cell . Members of the genus methylosinus and strains of the photosynthetic bacterium rhodomicrobium produce exospores .these are heat dessication and UV resistant . Is initiated by the appearance of the bud like enlargement and surrounding capsule at one end .
- 9. • Endospore formation : When certain essential elements like carbon ,nitrogen and phosphorus are limited or completely depleted or when water is unavailable certain gram (+) bacilli from specialized resting cells called endospores. These endospores are highly durable dehydrated cells which can survive extreme heat, lake of water, freezing and exposure to many toxic chemicals and radiation . The genera of bacteria giving rise to endospore
- 10. Germination The germination process occurs in three stages: ◦Activation ◦Initiation ◦Outgrowth.
- 11. Activation Even when placed in an environment that favors germination (eg. nutritionally rich medium) bacterial spores will not germinate unless first activated by one or another agent that damages the spore coat. Among the agents that can overcome spore dormancy are heat, abrasion, acidity, and componds containing free sulfhydryl groups.
- 12. Initiation Once activated, a spore will initiate germination if the environmental conditions are favorable. Different species have evolved receptors recognise different effectors as signaling a rich medium. Binding of the effector activates an autolysin that rapidly degrades the cortex peptidoglycan. Water is taken up, calcium dipicolinate is released, and a variety of spore constituents are degraded by hydrolytic enzymes.
- 13. Degradation of the cortex and outer layers results in the emergence of a new vegetative cell consisting of the spore protoplast with its surrounding wall. A period of active biosynthesis follows. This period, which terminates in cell division, is called outgrowth. Outgrowh requires a supply of all nutrients essenial for cell growth. Out growth