Lecture notes in Microbiology

Bacterial Endospore: Definition, Characteristics, Structure and its Formation


Bacterial Endospore

Bacterial Endospores
(Structure, Characteristics, Significance, Formation and Germination of Bacterial Endospores)

What are Endospores?

Bacterial endospores are special tough, dormant and resistant spores produced by some Gram-positive bacteria of Firmicute family during unfavorable environmental conditions. Endospores are developed within the vegetative cells (hence the name, endo = inside). They help the bacteria to endure the unfavorable environmental conditions. Another importance of endospores is that it can be easily dispersed by wind, water and through the gut of animals. Bacillus and Clostridium are the most studied endospore forming bacterial genera. Bacillus enters into endospore formation cycle when the carbon or nitrogen source is getting limited in the growing medium.

Who discovered endospores

John Tyndal (source cc wikipedia)

Who discovered the endospore?

Endospores were discovered by John Tyndall, a 19th century physicist. He discovered endospores as the heat resistant spores of bacteria which survived even after 100oC. He also discovered a simple cost effective process to kill bacterial endospores called Tyndallization.

What are the characteristics of Endospores?

The endospores are structurally, metabolically and functionally very different from bacterial vegetative cells. The main characteristics of bacterial endospores are giving below:

Learn more: Difference between Endospore and Vegetative Cells

Ø  Endospores are exceptionally resistant to stressful environmental conditions such as heat, ultraviolet radiation, gamma radiation, chemical disinfectants and desiccation.

Ø  Most of the endospores are viable for many years, even for 10, 000 years or more.

Ø  Due to this long viability and their adaptations to stress conditions, most of the endospores producing bacteria are notorious pathogens.

Ø  Wiping with alcohol or hydrogen peroxide or boiling at 100oC will not kill the bacterial endospores.

Ø  However, endospores can be killed by autoclaving (at 121oC).

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