Oxidative stress responses of pathogen bacteria in poultry to plasma-activated lactic acid solutions

Abstract Investigation of the plasma-activated liquid has seen some success, yet no studies have systematically explored the potential damage from oxidative stress against the bacteria. In this study, the oxidative stress response of Salmonella Enteritidis suffered from plasma-activated lactic acid (PALA) solutions was assessed. PALA solution was made by treating 300-mL of lactic acid (LA, 0.05–0.20%) solution with a plasma jet for 40–100 s. The results revealed that a 6.86 log-reduction of S. Enteritidis was detected when 0.20% LA solution was treated with plasma for 80 s. The reactive oxygen species (ROS) in PALA solutions enhanced the intracellular ROS level that cannot be rescued by major anti-oxidative enzymes, such as superoxide dismutase (SOD) and catalase (CAT). Gel electrophoresis and liquid chromatography-tandem mass spectrometry (LC-MS/MS) indicated the generated ROS resulted in the increase of carbonyls content and the fragmentation of outer membrane protein A (OmpA) of S. Enteritidis. Further, such property makes PALA a superior sanitizer for poultry meat compared to widely used sodium hypochlorite (NaClO) and lactic acid (LA). This study not only provides a theoretical basis for developing novel sanitizer but also enables PALA to find a way for practical application.