VMC 211: General Veterinary Microbiology (1+1)

STRUCTURE OF ENDOSPORE

• Endospores are made up of a central spore cell, which is surrounded by various layers. The outermost layer is the exosporium - a thin protein covering.
• Below this is the spore coat which is composed of highly cross-linked keratin and layers of spore-specific proteins. The cortex consists of loosely cross-linked peptidoglycan and contains dipicolinic acid (DPA), which is particular to all bacterial endospores.
• Core - The core contains the cell wall and, cytoplasmic membrane, nucleoid, and cytoplasm. The core only has 10-30% of the water content of vegetative cells; therefore the core cytoplasm is in a gel state. The low water content contributes to the endospores success in dry environments. However, the low water concentration and gel cytoplasm contributes to the inactivity of cytoplasmic enzymes. Small acid soluble spore proteins (SASPs), are formed during sporulation and bind to DNA in the core. SASPs protect the DNA from UV light, desiccation, and dry heat. SASPs also serve as a carbon energy source during germination.