TMT-based quantitative proteomic and scanning electron microscopy reveals biological and morphological changes of Staphylococcus aureus irradiated by electron beam

Abstract

Electron beam irradiation is an efficient cold sterilization technique that has been widely utilized in food preservation. To understand the biological and morphological changes of microorganisms by electron beam irradiation, the D10 value, growth curve, and morphological characterization by scanning electron microscope (SEM) of Staphylococcus aureus were studied. Furthermore, Tandem mass tag (TMT)-based quantitative proteomic was performed to investigate the responses of Staphylococcus aureus to electron beam. The results showed that electron beam prolonged the lag phase of bacterial growth, and irradiated bacteria were more sensitive to irradiation than unirradiated bacteria. Compared to unirradiated cells, there were 53, 96, 1055, and 431 differentially expressed proteins (DEPs) detected in 1-kGy and 2-kGy irradiated cells after 0 h and 24 h incubation, respectively. Most of the DEPs involved in DNA repair were found to be up-regulated, whereas those involved in biofilm formation and staphylococcal enterotoxin production were down-regulated. No noticeable morphological changes were observed in irradiated S. aureus. These findings provided valuable information in the responses of S. aureus to electron beam irradiation, leading to a better understanding of the effects of electron beam irradiation on food pathogens.