Prokaryotic Expression and Preliminary Application of Lys40, an Endolysin from Broad-Host-Range Salmonella enterica...

Phage endolysins are considered promising novel antimicrobial agents capable of inducing rapid bacterial lysis through efficient degradation of peptidoglycan layers in the cell wall. In this study, the endolysin-encoding gene Lys40 from Salmonella phage SP_4 was subjected to comprehensive bioinformatic analysis. The results indicated that Lys40 contains eight α-helices and two β-strands, belongs to the lyz_endolysin_autolysin domain family (residues 10-147), and lacks both a signal peptide and transmembrane regions. A recombinant expression system was constructed using the pET28b(+) vector and Escherichia coli BL21 (DE3), enabling successful soluble expression of Lys40. Antimicrobial assays demonstrated that, when combined with the permeabilizer EDTA, Lys40 exhibited significant lytic activity not only against Salmonella but also toward E. coli. The observed synergistic antibacterial effect of Lys40 combined with EDTA in this study provides experimental data support for the development of novel antimicrobial agents.