What is the primary mechanism of microbial inactivation in saturated steam sterilization?

The primary mechanism of microbial inactivation in saturated steam sterilization is the denaturation of essential cellular proteins. Denaturation refers to the process where proteins lose their three-dimensional structure, rendering them non-functional. This occurs due to the high temperature and moisture present in saturated steam. Specifically, the heat from the steam provides the energy required to break the weak bonds, such as hydrogen bonds and hydrophobic interactions, that maintain the protein's shape. The presence of moisture, in the form of saturated steam, facilitates this denaturation process by allowing water molecules to interact with the protein molecules, further disrupting their structure and accelerating the unfolding process. Because properly folded proteins are necessary for microbes to survive and replicate, the irreversible denaturation of these proteins leads to the death of microorganisms. This mechanism is more efficient at lower temperatures compared to dry heat sterilization due to the presence of moisture. Saturated steam is used because it provides both the heat and moisture needed for optimal protein denaturation, ensuring effective sterilization.