Bacterial Endospores

Abstract

The spores of bacteria formed mainly by members of the genera Bacillus and Clostridium are termed endospores because they develop singly within the mother or sporangial cells. Spore formation is a complex differentiation process involving two cells and a programme of gene expression requiring intracellular communication. Endospores exhibit complete metabolic dormancy and extreme resistance to multiple environmental insults, and can survive for centuries. The production of resistant spores by certain pathogenic bacterial species contributes to their transmission and difficulties in preventing their reoccurrence. Dormancy and resistance properties derive from alterations in the spore cell cytoplasmic contents, including dehydration, and from multiple integument layers. When presented with a nutrient-rich environment, spores can rapidly germinate and re-enter vegetative growth cycle.

Key Concepts:

• Bacterial endospores can survive for decades and are highly resistant to numerous environmental insults.

• The resistance properties of bacterial endospores contribute to their roles in food spoilage and in human and animal pathogenesis.

• Bacterial endospores are cells with specialised modifications to their structure and contents.

• Bacterial endospores are produced via a simple developmental process involving cooperative and regulated gene expression of two cells.

• Heat resistance of bacterial endospores is determined by several factors, the most important being the relative dehydration of the spore core.

• Bacterial endospores possess a unique mode of resistance to UV irradiation involving specialised DNA-binding proteins.