## 4 Discussion  
### AgNP-BK510 Lys Characterization and Antimicrobial Efficiency  
AgNPs were synthesized using silver nitrate (AgNO\({}_{3}\)) and the reducing agent \(L\). _virginicum_ extract; the use of any other agent to enhance the stability of AgNPs was not necessary. The successful synthesis of AgNPs was visually confirmed by the color change of the solution from green to brown, indicative of nanoparticle formation. According to [PERSON] et al. (2018), UV-Vis absorption spectroscopy is very suitable for detecting the wavelength and absorption corresponding to the surface plasmon resonance band. Additionally, previous studies have established relationships between particle size, bandwidth, and solution coloration with the maximum wavelength of absorption bands displayed in electronic spectra ([PERSON] _et al._, 2018). Zeta potential measurements play a crucial role in providing valuable data about nanoparticle agglomeration, distribution, and stability in solution ([PERSON] _et al._, 2018). The AgNPs sample exhibited a Zeta potential value close to \(-\)38.7 mV, indicating a high level of stability for the nanoparticles in the solution. The nanoparticles demonstrated high stability over a period of approximately 40 days, as observed from consistent size and Zeta potential values. TEM has a high accuracy and reliability for determining the shape, distribution, size, and composition of AgNPs. TEM images showed that the sample is composed of well-dispersed spherical AgNPs, an average diameter of 16.06 \(\pm\) 4.23 nm for the AgNPs, and a small size, indicative of an efficient synthesis process (Figure 1). TEM images for AgNPs-BK510 Lys (Figure 2) suggest that the AgNPs are dispersed inside the BK510 Lys clusters and prove the formation of AgNPs-BK510 Lys conjugates. Average diameters of uncoated AgNPs were obtained between 10 and 25 nm (Figure 1c). With the conjugation process, the variation of the diameters ranged from 50 nm to 90 nm on average, which indicated the surface coating with endolysins (Figure 2). It is observed in Figure 2a,b that the nanoparticles coated with endolysins maintain a hemispherical morphology and form clusters of coated nanoparticles. It is known that electrostatic interactions, hydrophobic interactions, and hydrogen bonding are commonly implicated in the protein-nanoparticle binding process ([PERSON] _et al._, 2018). [PERSON] et al. (2018) studied the adsorption behavior of lactoferrin onto silver nanoparticles using the isothermal titration calorimetry technique (ITC). The findings elucidate that there were no substantial impacts on the protein's conformation and stability caused by van der Waals interactions and hydrogen bonding. In a separate study, [PERSON] et al. (2018) studied the AgNPs-PlyB221 endolysin conjugates using the ITC analysis. They found that PlyB221's adsorption onto the AgNPs interface  
Figure 6: Standardized Pareto chart for Lytic Activity using: (**a**) BK510 Lys; (**b**) AgNP-BK510 Lys. Grey (+) and blue (\(-\)). occurred spontaneously, and the primary interactions governing this process were van der Waals and hydrogen bond interactions. In the case of AgNPs-BK510 Lys, the mechanism is still unknown and will need to be studied in greater depth in the future. Table 4 shows the inhibition diameters obtained for each strain tested. All strains showed inhibition with AgNPs, and only _S. aureus_ with BK510 Lys endolysins. This was to be expected as there are several references on the antimicrobial properties of AgNPs [20; 21], and since the endolysin comes from a _S. aureus_ bacteriophage, it should present inhibition. It is observed that in the conjugates, there is a synergy that allows for greater efficiency, compared to the AgNPs, in the strains of _S. aureus_, _E. coli_, _Salmonella_ sp., and _Klebsiella_ sp. (Figure 3a), being 24, 24, 100 and 40% higher, respectively. In the strains of _Listeria_ sp. and _P. vulgaris_, the efficiency was maintained, whereas, in the strains of _P. mirabillis_ and _P.