Mechanism of microbial spore inactivation through electromagnetic radiations: a review

Spores are the biological structures formed out of sporulation from vegetative cells in adverse conditions. Being tolerant to many extreme environment and conditions, they escape and survives critical processing steps in the food industry that poses food and health safety problems, as is evident from the increase in reports of food-borne outbreaks due to spore-formers. Electromagnetic radiation (EM) is used for rapid decontamination and sterilization purposes in the food industry. Many studies have reported a greater reduction in spore population upon irradiation with EM rays due to its impact on genomic material and other components of spores that destabilises overall structure and brings clonogenic death. However, there is scattered literature regarding the mechanism of its inactivation and resistance against such damage. This review attempts to concisely evaluate the potential of electromagnetic radiations in spore inactivation and details its mechanism through a collective study of scientific results and reports. It also briefs about the process of sporulation, the structure of spores and the role of its components in the resistance of spores to damage. Many studies, which demonstrated that combining various EM treatments might be an effective way for inactivation of spores, were discussed in detail.