Learning Objective:

Describe the structure, function, and resistance mechanisms of bacterial endospores

Organisms that form endospores:

• Bacillus
• Clostridium

Primary Function

Endospores are survival structures, not reproductive forms.

• 1 bacterium → 1 endospore → 1 bacterium
• Designed to withstand extreme environmental stress, including:
  • Chemical exposure
  • Desiccation (drying)
  • Radiation
  • Freezing
  • High temperatures

Activity

Mechanisms of Resistance

Endospore resistance is due to several structural and biochemical adaptations:

• Synthesis of new enzymes
  • Dipicolinic acid synthetase
  • Heat-resistant catalase
• Alteration of metabolic enzyme activity
  • Selective increase or decrease in enzyme function
• Core dehydration
  • Presence of calcium dipicolinate reduces water content
  • Enhances thermal resistance
• Thick keratin-like spore coat
  • Provides physical and chemical protection

Activity

Note

Fungal spores serve a reproductive function, unlike bacterial endospores.

Activity