Bacillus and Other Spore-Forming Genera: Variations in Responses and Mechanisms for Survival

The ubiquity of Bacilli endospores in soils facilitates their easy transfer routes to other environments, including cleanrooms and low-biomass sites required by many industries such as food production and processing. A bacterial endospore is a metabolically dormant form of life that is much more resistant to heat, desiccation, lack of nutrients, exposure to UV and gamma radiation, organic chemicals, and oxidizing agents than is a vegetative cell. For example, the heat tolerance of endospores depends on multiple factors such as sporulation temperature, core dehydration, and the presence of minerals and small, acid-soluble proteins (SASPs) in the core. This review describes our current understanding of the persistence mechanisms related to sporeformers’ biochemical properties and discusses in detail spores’ heat, radiation, and reactive chemical resistance. In addition, it discusses the impact of contamination with spores on many areas of human activity, spore adhesive properties, and biofilm contribution to resistance.