Water and the bacterial spore: reesistance,dormancy and germination

摘要

Bacterial endospores are extremely dormant and resistant to heat,radiation,chemicals, and enzymes.Heat resistance is commonly 10~5-fold greater than that of the corresponding vgetative cell,or about 40-50 deg C higher.Spore resistance and dormancy mechanisms are multicomponent,including a low water content in the central protoplast,high levels of calcium dipicolinate (CaDPA),extreme immobilization of ions and small molecules,the protection of DNA by spore-specific small acid-soluble proteins (SASPs) whose binding to DNA is promoted by dehydration.The spore is compartmentalized.The central protoplast is surrounded by a wide cortex that consists mainly of peptidoglycan and is further surrounded by proteinaceuous coats.Protoplast water contents have not been measued directly,but estimates range from about 20 to 50