###### Abstract
Additionally, the production of further plasma-generated compounds (PGCs) such as plasma-processed air (PPA) and plasma-treated water (PTW) embraces a conglomeration of chemical reactions in different surroundings (water, air), which make the whole process extremely complex [1, 2]. Therefore, it is not only important to know the composition of the plasma gas, but also the chemical interactions with the ambient air and the treated water. PPA and PTW, which are mixtures of compounds originating from these complex chemical pathways, possess antimicrobial effects. The PTW produced by the MidiPExc was not affected by any significant temperature changes during the treatment and reached pH values of 2.59, 1.93 and 1.22 at pretreatment times of 100, 300 and 900 s. The most important molecular components of the PTW were hydrogen peroxide (H\({}_{2}\)O\({}_{2}\)), nitrate (NO\({}_{3}\)-), nitrite (NO\({}_{2}\)-) and a third component which could not be clearly identified so far but was most likely peroxynitrite (ONOO-). At 100 s pretreatment time, the following concentrations could be measured--H\({}_{2}\)O\({}_{2}\): 77 mg/L, NO\({}_{3}\)-\(3.4\) mg/L, NO\({}_{2}\)-: 241.32 mg/L, ONOO-: 9.968 mg/L. At 300 s pretreatment--H\({}_{2}\)O\({}_{2}\): 297 mg/L, NO\({}_{3}\)-: 27.06 mg/L, NO\({}_{2}\)-: 893.54 mg/L, ONOO-: 65.23 mg/L and at 900 s pretreatment--H\({}_{2}\)O\({}_{2}\): 717.3 mg/L, NO\({}_{3}\)-: 72.29 mg/L, NO\({}_{2}\)-: 1600.71 mg/L and ONOO-: 224.57 mg/L [3]. Despite this fact, the mechanism of action of these substances on bacterial biofilms is still unknown. The antimicrobial effects have been demonstrated for various products such as vegetables, fruits, and meat, as well as dairy products and further processed food products [4, 5, 6, 7, 8, 9, 10, 11]. Nonetheless, it is of crucial importance to achieve an antimicrobial effect on pathogens without damaging the product itself [12]. Thus, challenges of plasma treatment are comparable with demands of the treatment of medical devices, where the pathogens must be destroyed without harming the patients or their tissues [13]. Despite these challenging factors, especially PPA and PTW have gained interest in the food industry. _Pseudomonas fluorescens_, a Gram-negative, oxidase-positive, rod-shaped bacterium, is frequently found as a spoilage microbe in the food industry [14, 15] and as a commensal in the digestive tract of humans [16]. At the same time, some _P. fluorescens_ strains naturally occur as a plant-growth-promoting rhizobacterium [17]. _P. fluorescens_ is a common contaminant in the dairy industry, where it releases blue nondiffusible pigments on cheese during its production [18]. Furthermore, it frequently contaminates refrigerated products like meat or milk and fish products such as cod or haddock [15, 19, 20, 21]. _P. fluorescens_ forms biofilms composed of an extracellular matrix (ECM) [22]. When cells adhere unspecifically to surfaces, cellular and physiological changes occur, which enhance ECM formation [23, 24]. Several environmental factors, such as the osmolarity or nutrient availability, affect the ability of _P. fluorescens_ to attach to abiotic surfaces. However, iron has been proven to be the most crucial factor for biofilm adhesion [25]. A wide range of genes, e.g., flagella or Clp protease synthesis, appear to be crucial for tight surface attachment [26]. Generally, a decisive factor for a long-term survival strategy of the bacterial cells is the detachment from the mature biofilm, subsequently followed by colonization of new regions via an undirected diffusion [27]. Besides, the access to essential compounds like oxygen, or the release of specific lyase enzymes seem to be crucial triggers for the detachment of biofilms [28]. As a consequence, these factors lead to a disintegration of the ECM and a release of cells into the surrounding medium. Concerning rinsing processes in industrial applications, the dispersion of the organism into other areas only plays a minor role.