BACTERIAL SPORE

• Bacterial spore means sporulation of bacteria ( formation of bacterial spore).

• Bacterial spore are the most dormant form of bacteria.

• Gram positive bacteria are the best known for producing intracellular spores called endospores.

• Bacterial spore is small, round or oval body that form in bacteria due to cytoplasmic dysfunction during unfavourable condition.

• Bacterial structure are remarkable structure enabling bacteria to survive extreme environmental condition.

• Spore play a significant role in food microbiology to ensuring the safety and shelf life.

• Spore are resistant to nutrition starvation temperature extreme ph, antibiotic, etc.

Structure and composition of bacterial spores

1. Exosporium:

· The exosporium is the outermost layer of the spore

· It is composed of protein and glycoprotein

· Provide protection

· Composition is different in different bacterial species.

2. Coat:

· Lies beneath the exosporium and surround the spore coat

· Consist of several level of protein

· Provide structural integrity

· Contains enzyme involved spore germination

3. Cortex:

· Located after the coat

· Cortex is the thick layer of peptidoglycan

· Provide protection against lytic enzyme during germination

4. Core:

· Inner most layer of spore

· Contain spore genetic material and essential component

· Consist of DNA, Ribosomes, Enzymes, etc

Sporulation process

Initiation of sporulation:

· When bacteria sense unfavourable condition like nutrient scarity or environmental stress they start the sporulation process.

Septum formation:

· The bacterial cell divide into two compartment a smaller one called the spore and a larger one called the mother.

Asymmetric division:

· The mother cell wraps around the spore forming a double layered membrane.

Cortex and coat formation:

· The cell deposit layer of tought material around the forespore providing protection.

Maturation:

· The spore mature by dehydrating making it resistant to heat, radiation and chemical

Spore release:

• Eventually the mother cell release the mature spore into the environment.

Shape and position of bacterial spore

· Spore may be central, terminal and sub-terminal

· Shape – oval or spherical in shape

· The diameter of spore may be same or less than the width of bacteria or may be wider than the bacillary body producing a distension or bulge in the cell.

Resistance

· Bacterial spores are extremely resistant to ordinary boiling, disinfectant and heating.

· Spores of all medically important bacteria are destroyed by autoclaving at 121 C for 15 minutes.

Spore germination

• Endospore remain dormant for year. But under favourable condition each endospore germination to give rise to a vegetative cell.

• Spore germination involve three stages.

1. Activation

2. Germination

3. Outgrowth

Demonastration

1. Gram staining: spore appear as an unstained refractile body within the cell.

2. Modified ZN stain

Uses of spores

· Indicator for proper sterilization.

Example- Bacillus sterothermophilus