Integrated Transcriptomic and Proteomic Analysis Reveals Antibacterial Responses of Staphylococcus aureus to 60Co γ-Irradiation

Abstract γ-Irradiation is a widely used nonthermal sterilization technology in food processing; however, the mechanisms underlying γ-irradiation-induced inactivation of Staphylococcus aureus (S. aureus) remain incompletely understood. This study investigated the effects of 60Co γ-irradiation on S. aureus and its molecular responses by integrating physiological assays with transcriptomic and proteomic analyses. γ-Irradiation produced a dose-dependent reduction in bacterial culturability from 0 to 2.0 kGy, with the greatest reduction observed at 2.0 kGy. Although no obvious surface morphological alterations were detected by scanning electron microscopy, γ-irradiation compromised membrane integrity, as evidenced by increased leakage of nucleic acids, proteins, and K+ and decreased ATPase-associated activities. Integrated omics analysis identified 486 differentially expressed genes and 178 differentially expressed proteins following 2.0 kGy irradiation. Functional enrichment analysis revealed alterations in pathways associated with cell envelope biosynthesis, amino acid metabolism, and energy metabolism. Notably, upregulation of MNH antiporters suggested a potential adaptive response to maintain cellular ion homeostasis under irradiation stress. Collectively, these findings indicate that γ-irradiation induces S. aureus inactivation through multiple cellular alterations, including membrane dysfunction, genomic damage, intracellular leakage, and metabolic disturbances.