Bacterial Spore Formation

Sporulation Process in Bacteria

Vegetative Phase

  • Bacteria grow as vegetative cells.

  • Cells divide by binary fission when:

    • Nutrients are available.

    • Environmental conditions are favorable.

Initiation of Sporulation

  • Triggered by:

    • Nutrient depletion.

    • Adverse environmental conditions.

  • Mother Cell Formation:

    • DNA condenses and aligns in the center.

    • The vegetative cell becomes the mother cell.

Development of the Spore

  1. DNA Division:

    • DNA divides into two complete copies.

  2. Membrane Invagination:

    • Mother cell membrane invaginates, forming the developing spore.

    • The membrane engulfs the developing spore, resulting in two membrane layers around it.

Formation of the Cortex

  • Peptidoglycan Layer:

    • Laid down between the two membranes.

  • Dipicolinic Acid:

    • Formed inside the spore.

  • Calcium Incorporation:

    • Calcium enters from the outside, leading to water removal.

  • Protein Coat Formation:

    • Forms exterior to the cortex, leading to maturation.

  • Some spores may develop an exosporium (additional layer).

Final Stages

  • Mature Spore:

    • Resistant to harsh environmental conditions.

  • Release:

    • Lytic enzymes destroy the mother cell, releasing the mature spore.