# Antimicrobial Activity of L-Lysine and Poly-L-Lysine with Pulsed Electric Fields  
[PERSON]  
1 Laboratory of Biodeterioration Research, Nature Research Centre, 08412 Vilnius, Lithuania;  
[EMAIL_ADDRESS] (V.R.); [EMAIL_ADDRESS] (A.P.)1  
[PERSON]  
2 Faculty of Electronics, Vilnius Geodiminas Technical University, 08412 Vilnius, Lithuania;  
[EMAIL_ADDRESS] (V.N.); [EMAIL_ADDRESS] (J.N.)2  
[PERSON]  
3 State Research Institute Center for Physical Sciences and Technology, 03227 Vilnius, Lithuania;  
[EMAIL_ADDRESS]  
[PERSON]  
1 Laboratory of Biodeterioration Research, Nature Research Centre, 08412 Vilnius, Lithuania;  
[EMAIL_ADDRESS] (V.R.); [EMAIL_ADDRESS] (A.P.)1  
[PERSON]  
4 Laboratory of Mycology, Nature Research Centre, 08412 Vilnius, Lithuania;  
[EMAIL_ADDRESS] (V.R.); [EMAIL_ADDRESS] (A.P.)1  
[PERSON]  
1 Laboratory of Biodeterioration Research, Nature Research Centre, 08412 Vilnius, Lithuania;  
[EMAIL_ADDRESS] (V.R.); [EMAIL_ADDRESS] (A.P.)1  
[PERSON]  
4 Laboratory of Mycology, Nature Research Centre, 08412 Vilnius, Lithuania;  
[EMAIL_ADDRESS] (V.R.); [EMAIL_ADDRESS] (A.P.)1  
[PERSON]  
1 Laboratory of Biodeterioration Research, Nature Research Centre, 08412 Vilnius, Lithuania;  
[EMAIL_ADDRESS] (V.R.); [EMAIL_ADDRESS] (A.P.)1  
[PERSON]  
1 Laboratory of Biodeterioration Research, Nature Research Centre, 08412 Vilnius, Lithuania;  
[EMAIL_ADDRESS] (V.R.); [EMAIL_ADDRESS] (A.P.)1  
[EMAIL_ADDRESS] (A.  
cells are exposed to high-intensity PEFs [19]. This methodology is very flexible in terms of parameters and there is a possibility to apply reversible [20] and irreversible permeabilization [21]. This already has found application in the food industry [22], clinics [23] and biotechnology [24]. Recently, potential application for wound decontamination was described [25; 26; 27]. Furthermore, electroporation is very useful when the targeted chemical compounds delivery is required. For example, in cancer treatment, electrochemotherapy is used for drug delivery, which significantly reduces the toxicity of the treatment [28]. In food processing, PEF-based delivery of nanoparticles [29], nisin [30] or other bioactive compounds [31] is also possible, which usually leads to non-thermal bacteria inactivation.  
Recently, it was demonstrated that PEF can be used for antibiotics for bacteria sensitization [32; 33; 34]. However, it does not solve the resistance problem entirely. Therefore, to find new agents to treat bacterial or other infections is an important and challenging task. The possibility to use electroporation could improve the treatment. In this work, we studied the antimicrobial properties of L-lysine (Lys) and poly-L-lysine (PLL) by combining them with PEF. The L-lysine was selected because it contains positively charged cationic groups of amino acids, which are very effective in destroying the membranes of the bacteria, thereby killing the bacteria [35; 36]. However, poly-L-lysine shows antibacterial properties, can resist in a harsh environment, induces no inflammation of the tissue [37] and can be toxic only in high doses [38]. In this study, for the first time, the possibility to use L-lysine and poly-L-lysine as additives for antimicrobial therapy when combing with PEF is reported. This new method could be potentially applied both in biomedical and food processing areas.  
Nevertheless, it should be noted that PEF-based treatment depends on the pulse parameters [39]. In this study, typical amplitudes of 15 and 30 kV/cm, usually used in antimicrobial studies, were applied [26; 34]. The effect of pulse durations in the range of 500 ns to 100 \(\upmu\)s were also investigated. Electroporation is a polarization-based phenomenon [40; 41], and this could be the diminished effect of sub-microsecond duration due to the cell polarization constant being comparable or higher than the pulse duration. Our study presents a multiparametric approach to define the PEF effects by combining L-lysine and poly-L-lysine.