Inactivation of suspended cells and biofilms of the gram-negative bacteria by electron beam irradiation and possible mechanisms of action

Abstract

Food-borne pathogens and biofilm formation pose a serious threat to seafood safety. The objective of this study was to evaluate the inactivation effect of electron beam irradiation on the suspension and biofilms of Vibrio parahaemolyticus (V. parahaemolyticus), Pseudomonas fluorescens (P. fluorescens), and Shewanella putrefaciens (S. putrefaciens) in vitro and on the surface of large croaker and the possible mechanisms of action. The results showed that electron beam irradiation could significantly reduce the number of viable bacteria both in vitro and on the surface of the large yellow croaker samples and could destroy the extracellular polymers (EPS) of biofilms. Mechanism studies showed that the increased Reactive Oxygen Species (ROS) levels after irradiation treatment resulted in damage to the plasma membrane of bacterial cells, while the cell wall was intact. In addition, the nucleic acids of the bacteria were significantly damaged after irradiation, but the primary protein structure was not changed. These findings provide the internal mechanism of the effect of electron beam irradiation on Gram-negative bacteria and indicate that electron beam irradiation could be used as an effective method to control spoilage bacteria and pathogenic bacteria biofilms on the surface of seafood.