## 3 Results and Discussion  
### Minimal Inhibitory Concentration  
MIC was used as a comparative measure of the effectiveness of two different disinfectants: \(N\)-ethyl-\(N\),\(N\)-dimethylhexadecylammonium bromide (QAC) and peracetic acid (PAA) against _Asaia_ spp. Figure 1 presents the MICs of QAC (Figure 1A) and PAA (Figure 1B) for six tested bacterial strains. The sensitivity of _Asaia_ spp. to disinfectants was strain-dependent. The bacteria were characterized by similar sensitivity to QAC, but differentiation was noticeably more pronounced in the case of sensitivity to PAA. In general, higher sensitivity was observed for QAC, with MIC values ranging from 0.0156% to 0.0313% (\(w/v\)). For PAA, these values ranged from 0.0625 to 0.250% (\(v/v\)). The strain _As. bogorensis_ FFMW was the most resistant to PAA and was also characterized by high resistance to QAC. It is worth noting that the MICs for QAC were almost 10 times lower in comparison to those obtained for PAA. [PERSON] and co-workers obtained MIC results for dodecyl(trimethyl) ammonium bromide against _As. lannensis_ FMW1 of 0.12-0.25 uM, dependent on both the type of carbon source and the availability of nutrients in the environment. They conclude that culture media with highly complex components may protect microorganisms from the presence of antimicrobial compounds [24]. The activity of PAA may be dependent not only on the kind of bacterial strain, but also on its metabolic activity. In a study conducted by [PERSON] and [PERSON], the minimal inhibitory concentration of PAA against expotentially-growing _Pseudomonas aeruginosa_ cells was 100 ug/mL, while for cells from stationary phase the concentration was four times higher. The authors suggest that the resistance of _P. aeruginosa_ cells harvested from stationary phase was comparable to that of bacterial cells forming biofilms [25]. PAA is considered to be a strong oxidizing agent, with effective action against a wide spectrum of microorganisms [26]. The antimicrobial activity of this compound is based on the disruption of membranes, oxidation of thiol groups in proteins, and damage to DNA [27]. Despite the widespread use of PAA as an antimicrobial agent, the mechanisms of microbial tolerance to PAA are not fully understood. The QAC group includes both cationic surfactants and antimicrobial agents showing particular activity against yeasts and molds. However, they are also commonly used against Gram-positive and Gram-negative bacteria. The antimicrobial activity of these substances depends mainly on the length of the \(N\)-alkyl chain [28]. Disinfectants based on QAC are used widely in the pharmaceutical, cosmetic, and food industries [29]. Generally, the antimicrobial activity of QAC is based on interaction with cell membranes, disruption of membrane integrity and leakage of intracellular content [30]. The mechanism of antimicrobial activity involves the association of positively-charged quaternary nitrogen with negatively-charged head groups of acidic phospholipids in the bacterial membranes. The hydrophobic tail of the quaternary ammonium compound integrates into the microbial hydrophobic membrane core. The activity of QAC may also involve the disruption and denaturation of proteins and enzymes, as well as induction of dose- and time-dependent ultrastructural changes [28]. At low concentrations, the activity of QAC results in the loss of osmoregulatory capability and leakage of potassium ions and protons. Intermediate levels of QAC in turn disrupt membrane-association processes (respiration, transport, cell wall biosynthesis) [31]. However, it is well known that Gram-negative bacteria exhibit particular resistance to numerous biocides, including quaternary ammonium compounds. One of the reasons for this is the long-term use of the same types of disinfectant in the food industry.