# Metabolomics of _Pseudomonas aeruginosa_ Treated by Atmospheric-Pressure Cold Plasma
## 1 Introduction  
_Pseudomonas aeruginosa_, is widely distributed in nature and is one of the most common bacteria in soil. According to the World Health Organization, _Pseudomonas aeruginosa_ ranks second [1, 2, 3] among all bacterial infections. However, due to the high infection rate of _Pseudomonas aeruginosa_, it has a high level of drug resistance, and so a new sterilization method is needed [4]. Atmospheric-pressure low-temperature plasma is a new technology where the temperature is similar to room temperature, so that plasma can be directly used in the treatment of organisms. Atmospheric-pressure cold plasma has been developed for biomedical applications, such as skin disease treatment, cancer treatment, beauty treatments for skin, dentistry, disinfection and sterilization applications [5, 6, 7, 8, 9, 10, 11]. Low-temperature plasma has the advantages of a low sterilization temperature, fast sterilization, no by-products and relatively comprehensive sterilization [9, 12, 13]. At the same time, the cost of plasma sterilization is much lower than that of traditional sterilization [14]. [PERSON] et al. found that both ultraviolet light and oxidation-active substances in plasma can inactivate spores [15]. [PERSON] et al. found that the main role of plasma in sterilization is the role of ultraviolet light [16].  
[PERSON] et al. studied the changes of cyanobacteria, _Clostridum_ and other bacteria in raw pond water treated with plasma [17]. [PERSON] et al. studied an atmospheric micro-plasma jet device and found that it could inactivate _Pseudomonas_ sp HB1 in water, and studied the effect of various active particles on sterilization [18]. [PERSON] et al. found that active substancesare the main cause of plasma sterilization [19]. [PERSON] et al. studied a dielectric barrier discharge (DBD) plasma discharge device and found that the active substance produced by DBD can inhibit the growth of pathogens such as bacteria [20]. [PERSON] et al. studied a coaxial plasma using helium gas as the working gas, and evaluated its sterilization effect by using _Escherichia coli_. They found that the plasma had a significant bactericidal effect [21]. [PERSON] et al. found that the primary cause of nitrogen plasma sterilization was the active particle ONOO\({}^{-}\)[22], and [PERSON] et al. investigated the effect of different working gases on bactericidal efficacy [23]. [PERSON] et al. reported a plasma-based nanomaterial that promotes apoptosis of cancer cells [24]. [PERSON] et al. found that plasma-treated lysozyme can significantly induce apoptosis of cancer cells [25]. [PERSON] et al. found that plasma treatment can cause autophagy and apoptosis of cancer cells, thus inhibiting the spread of cancer [26]. [PERSON]'s study found that plasma activated normal saline induce colon cancer cell deaths by stimulating the immune response [27]. Bacterial metabolism is an important activity in life, so studying the effect of plasma on bacterial metabolism is of great significance [28; 29; 30].  
The influence of bacterial metabolism after plasma treatment has seldom been reported, and so in this study we used a portable plasma discharge device of activated water for treating _Pseudomonas aeruginosa_. We then detected the metabolites to study the changes in bacterial metabolites and signaling pathways.