Insight into the surface discharge cold plasma efficient inactivation of Pseudomonas fluorescens in water based on exogenous reactive oxygen and nitrogen species: Synergistic mechanism and energy benefits

As well known, surface discharge cold plasma has efficient inactivation ability and a variety of RONS are main active particles for inactivation, but their synergistic mechanism is still not clear. Therefore, surface discharge cold plasma system was applied to treat Pseudomonas fluorescens to study bacterial inactivation mechanism and energy benefit. Results showed that energy efficiency was directly proportional to applied voltage and inversely proportional to initial concentration. Cold plasma treatment for 20 min was inactivated by approximately >4-log10 Pseudomonas fluorescens and application of •OH and 1O2 scavengers significantly improved survival rate. In addition, •OH and 1O2 destroyed cell membrane structure and membrane permeability, which promoted diffusion of RONS into cells and affecting energy metabolism and antioxidant capacity, leading to bacterial inactivation. Furthermore, accumulation of intracellular NO and ONOOH was related to infiltration of exogenous RNS, while accumulation of •OH, H2O2, 1O2, O2- was the result of joint action of endogenous and exogenous ROS. Transcriptome analysis revealed that different RONS of cold plasma were responsible for Pseudomonas fluorescens inactivation and related to activation of intracellular antioxidant defense system and regulation of genes expression related to amino acid metabolism and energy metabolism, which promoting cellular process, catalytic activity and other biochemical pathways. In recent years, pathogenic microbial contamination has posed an escalating major challenge to global public health. One of the culprits, Pseudomonas fluorescens, has been shown to be widespread in many media, even drinking water. It can cause a variety of diseases, such as septicemia, intravascular coagulation, and even irreversible shock. Cold plasma is a new technology for inactivating pathogenic microorganisms without exogenous chemical reagents. Combining transcriptomics, cell morphology, and analytical chemistry, the oxidative stress and synergistic inactivation mechanism was investigated by analyzing the interaction between exogenous RONS and fluorescent pseudomonas. In addition, energy consumption was first used to evaluate the energy benefits.