Introductory Microbiology

Endospores

 
• Certain species of bacteria produce spores, either within the cell (endospores) or external to the cell (exospores). The spore is a metabolically dormant form, which under appropriate conditions, can undergo germination and out growth to form a vegetative cell. Endospores help the bacterial cell to tide over unfavourable environmental conditions.
• Endospores are thick walled, lightly refractive bodies that are produced by Bacillus, Clostridium and Sporosarcina, Thermoactinomyces, and a few other genera. Endospores are usually produced by cells growing in rich media but which are approching the end of active growth. They are extremely resistant to desiccation, staining, disinfecting chemicals, radiation and heat.
• All endospores contain large amounts of dipicolinic acid (DPA) accounts for 10-15% of the spores dry weight and occur in combinations with calcium and probably located in the core i.e., central part of the spore. The Ca-DPA complex may possibly play a role in the heat resistance of endospores. Synthesis of DPA and uptake of calcium occur during advanced stages of sporulation.
• During germination, lose their resistance to heat and staining. Subsequently, out growth occurs characterized by synthesis of new cell material and development of the organism into growing cell.