Bacterial Endospores

Question 1

What are endospores

Answer 1

Dormant structures formed by bacterial cells in unfavourable environments

Question 2

What genera of species can form endospores

Answer 2

• Gram-positive

- Mostly bacillus and clostridium

Question 3

How can cells be determined by their endospores

Answer 3

Endospore position is variable and characteristic for different cell types.

Question 4

Briefly explain the process of sporulation

Answer 4

1. Spore septum begins to isolate newly replicated DNA and small portion of cytoplasm
2. Plasma membrane starts to surround DNA, cytoplasm and membrane from step 1
3. Spore septum surround isolated portion forming forespore
4. Peptidoglycan later forms between membranes
5. Spore coat forms
6. Endospore is freed from cell

Question 5

Describe the structure of an endospore

Answer 5

Endospores are composed of a central spore surrounded by

• Exosporium: thin covering made of proteins
• Spore coat: highly cross linked keratin laters of spore specific enzymes
• Cortex: Loosely linked peptidoglycan
• Core: condensed chromosome, packaging proteins and spore specific compounds

Question 6

What causes sporulation?

Answer 6

Sporulation is a stress, last ditch attempt for survival that can only occur in active cells. Nutritional signals and population density can be triggers.

Question 7

Under what circumstances does activation / germination occur

Answer 7

Spores can be activated by heat and / or simple chemicals (e.g. L-alanine initiates germination on B. subtilis)

Question 8

What are the advantages and disadvantages of sportualtion

Answer 8

Advantage: Endospores can persist for a long time in an inert state.
Disadvantage: Germination is not guaranteed and is dependent on environmental signals

Question 9

What are endospores resistant to

Answer 9

Pressure
Vacuum
Dessiccation
Irradiation
Antibiotics
Chemical disinfectants
Extremes of pH
Heat