Inhibitory effect of cold nitrogen plasma on Salmonella Typhimurium biofilm and its application on poultry egg preservation

Abstract

Salmonella Typhimurium easily forms biofilms on poultry eggshell, which poses a serious threat to the safety of poultry egg. Therefore, this study aims to evaluate the inhibitory mechanism of cold nitrogen plasma (CNP) on Salmonella Typhimurium biofilm and apply it to poultry eggs to reduce the risk of contamination. The results of crystal violet staining showed that CNP can effectively remove biofilm. Electron paramagnetic resonance (EPR) spectra and reactive oxygen species (ROS) concentration analysis showed that CNP reacts with water to generate hydroxyl radicals and stimulate cells to cause an increase in intracellular oxidative stress. After treating biofilm with CNP (600 W, 2min), the metabolic activity of Salmonella Typhimurium decreased by 82.2%, and the extracellular protein, extracellular polysaccharide and extracellular DNA respectively decreased from 68.5 to 12.3 μg/mL, from 32.1 to 8.4 μg/mL, and 26.5 to 8.6 μg/mL qRT-PCR analysis showed that CNP treatment down-regulated the transcription of genes related to extracellular protein, extracellular polysaccharide and extracellular DNA. In addition, CNP could remove Salmonella Typhimurium biofilm on poultry eggshells without significantly affecting sensory quality.