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Introductory Microbiology

Microbial cells:

bacterial endospores

A bacterial superpower that

only a few types possess!

A few species of bacteria can produce tough

endospores.

https://commons.wikimedia.org/wiki/File:OSC_Microbio_02_04_Endospores.jpg

Stained

Endospores are highly resistant to

radiation, desiccation (drying out),

high temperatures, freezing, and

chemical disinfectants.

Endospores are produced by only a few types

of bacteria, including Bacillus and Clostridium

species.

Courtesy of the Public Health Image Library (Images),

Centers for Disease Control and Prevention

p://en.wikipedia.org/wiki/File:Bacillus_subtilis_Spore.jpg

Pathogenic Clostridium species:

C. botulinum (botulism)

C. tetani (tetanus)

C. perfringens (gas gangrene)

C. difficile (“C diff” - diarrhea)

Pathogenic Bacillus species:

B. anthracis (anthrax)

B. cereus (food poisoning)

Brock Biology of Microorganisms. Fig.2.

central endospore

terminal endospore

lateral

endospor

e

We see various morphologies of endospores

forming in different types of bacteria.

Mothe

r cell

Forespore

(developing

Endospores have different layers and

characteristics compared to vegetative cells.

Exosporium

DNA repair

enzymes

Nucleoid

Modified from

http://library.open.oregonstate.edu/microbiology/chapter/bacteria-internal-components/

& Core Wall/Spore Cell Wall

Endospores are dormant,

highly-resistant

Endospores have different layers and

characteristics compared to vegetative cells.

Modified from

http://library.open.oregonstate.edu/microbiology/chapter/bacteria-internal-components/

Exosporium

DNA repair

enzymes

Nucleoid

Dehydration

Lowered pH

Dormant (metabolically inacti

& Core Wall/Spore Cell Wall

http://library.open.oregonstate.edu/microbiology/chapter/bacteria-internal-components/

Sporulation is a complex developmental process

that results in an endospore.

It’s

challenging

to

control/kill

endospores.

Endospores have been best studied (and are of

most interest) in Bacillus and Clostridium species.

Courtesy of the Public Health Image Library (Images),

Centers for Disease Control and Prevention

http://en.wikipedia.org/wiki/File:Bacillus_subtilis_Spore.

Some endospore forming bacteria:

Bacillus, Clostridium, Geobacillus, Sporolactobacillus,

Sporosarcina, Thermoactinomyces.

(include pathogens: B. anthracis, C. botulinum, C.

difficile, C. perfringens, C. tetani)

Gram positive rod-shaped bacter

There are a small number of exceptional/unusual

Gram negative bacteria that produce endospores.

Metabacterium polyspora

Gastrointestinal symbiont

of the guinea pig

(E) Epulopiscium-like, and (F) Epulopiscium

Gastrointestinal symbionts of certain fish.

Hutchison, E. A., Miller, D. A., & Angert, E. R. (2016).

Sporulation in bacteria: beyond the standard model. In

The Bacterial Spore: from Molecules to Systems (pp. 87-

102). American Society of Microbiology.

https://micro.cornell.edu/research/epulopi

scium/metabacterium-polyspora/

These bacteria are MUCH larger than most, may produce

multiple endospores, and sporulation triggers appear to

differ from what’s been observed in most sporulating

bacteria. Generally, when discussing endospore-formers, we are

looking at Gram positive rods.

https://www.smithsonianmag.com/smithsonian-institution/anthrax-letters-terrorized-nation-now-decontaminated-public-