Endospore Flashcards
Describe the structure of a bacterial endospore.
The spore is surrounded by the exosporium, a thin delicate covering (Willey, et al., 2011, pp.81-84).
A coat made up of several layers of protein lies beneath (Willey, et al., 2011, pp.81-84).
The next layer is a cortex made up of peptidoglycan (Willey, et al., 2011, pp.81-84).
The core wall inside cortex surrounds the core (Willey, et al., 2011, pp.81-84).
The inner membrane separates the cortex from the core (Willey, et al., 2011, pp.81-84).
The core contains normal cell structures but is metabolically inactive and has very low water content (Willey, et al., 2011, pp.81-84).
References: Willey, J.M., Sherwood, L.M., Woolverton, C.J. (2011) Prescott’s Microbiology. 8th edn. New York: McGraw-Hill.
Describe the steps in sporulation.
Endospore formation has seven steps (Willey, et al., 2011, pp.81-84).
The first step is axial filament formation (Willey, et al., 2011, pp.81-84).
Next, the forespore filament is formed by the cell membrane folding inward and enclosing some DNA (Willey, et al., 2011, pp.81-84).
The forespore is then engulfed by a second membrane (Willey, et al, 2011, pp.81-84).
The cortex is formed next and calcium and dipicolinic acid are collected.
The fifth step is coat synthesis, followed by the maturation of the endospore (Willey, et al., 2011, pp.81-84).
Finally, lysis of sporangium occurs due to the activity of lytic enzymes causing spore liberation (Willey, et al., 2011, pp.81-84).
References: Willey, J.M., Sherwood, L.M., Woolverton, C.J. (2011) Prescott’s Microbiology. 8th edn. New York: McGraw-Hill.
Describe the steps in germination.
Endospore germination has three steps (Willey, et al., 2011, pp.81-84).
First is activation, where the spore is prepared for germination (Willey, et al., 2011, pp.81-84).
It can be caused by treatments such as heating (Willey, et al., 2011, pp.81-84).
Next is germination, where the spores dormant state is broken (Willey, et al., 2011, pp.81-84).
In this step, the spore either swells, ruptures or the spore coat is absorbed (Willey, et al., 2011, pp.81-84).
Heat resistance and refractility are decreased, and the spore contents are released (Willey, et al., 2011, pp.81-84).
The metabolic activity increases (Willey, et al., 2011, pp.81-84).
The final step is outgrowth, where new components are synthesised by the spore protoplast (Willey, et al., 2011, pp.81-84).
The spore protoplast emerges from the spore coat remains and develops into an active bacterium (Willey, et al., 2011, pp.81-84).
References: Willey, J.M., Sherwood, L.M., Woolverton, C.J. (2011) Prescott’s Microbiology. 8th edn. New York: McGraw-Hill.
How does the low water content of the spore contribute to its dormancy?
A low water content ensures the spore remains metabolically inactive as many enzymes function in an aqueous environment (Willey, et al., 2011, pp.81-84).
References: Willey, J.M., Sherwood, L.M., Woolverton, C.J. (2011) Prescott’s Microbiology. 8th edn. New York: McGraw-Hill.
Why are SASP’s important?
SASP’s are acid-soluble DNA binding proteins (Willey, et al., 2011, pp.81-84).
They are important as they protect the spores DNA (Willey, et al., 2011, pp.81-84).
References: Willey, J.M., Sherwood, L.M., Woolverton, C.J. (2011) Prescott’s Microbiology. 8th edn. New York: McGraw-Hill.
Describe how an endospore gains heat resistance.
The various layers of the endospore contribute to the endospores resistance to heat and other lethal agents (Willey, et al., 2011, pp.81-84).
For example, the exosporium and spore coat protect spore from chemicals (Willey, et al., 2011, pp.81-84).
The spore coat is also impermeable to toxic molecules (Willey, et al., 2011, pp.81-84).
The inner membrane is impermeable to various chemicals (Willey, et al., 2011, pp.81-84).
The core contributes to resistance by having a low water content, increased levels of dipicolinic acid complexed with calcium ions and decreased pH levels (Willey, et al., 2011, pp.81-84).
The core also contains SASP’s which saturate spore DNA (Willey, et al., 2011, pp.81-84).
References: Willey, J.M., Sherwood, L.M., Woolverton, C.J. (2011) Prescott’s Microbiology. 8th edn. New York: McGraw-Hill.
