ИСТИНА

Abstract P-28-029 New approaches and the development of innovative antimicrobial agents are urgently required to overcome bacterial resistance worldwide. Here we describe the results of the development of a gel formulated using bacterial alginate, incorporating a modified endolysin as the active component. For this, a recombinant modified endolysin with a broadened activity spectrum was constructed using genetic hybridization of LysSi3 endolysin with antimicrobial peptide (AMP) as an agent capable of permeabilizing the outer membrane of Gram-negative bacteria. For the modification a series of previously researched AMPs were assessed, and dose dependence, the spectrum of antimicrobial activity against clinical isolates of ESKAPE bacteria and their biofilms, the rate of action, and potential toxic effects were determined. Based on the obtained data, we selected a modification with an amphiphilic alpha-helical peptide consisting of leucine and lysine residues resulted in engineered LysSi3-LK. As carriers, we considered several bacterial alginates in the form of sodium salts, obtained during the cultivation of Azotobacter vinelandii 12. As a result, two alginates with high molecular weights were chosen for research: ALG2 and ALG3 (279 and 418 kDa, respectively), differing in acetylation and M/G monomer blocks ratios. Gels based on these biopolymers demonstrated significant differences in dissolving rate and viscosity. Both experimental antimicrobial compositions containing the endolysin in concentration 0.5 mg/ml were effective against MDR Acinetobacter baumannii strains. Stability studies of the resulting formulations showed that lysin did not degrade in the gel and retained 100% efficacy against growing bacterial culture within 3 months. Thus, the developed gels represent a promising form for further research as a potential ready-to-use topical antibacterial formulations. FEBS Open Bio 15 (Suppl. 2) (2025) 69–527 DOI: 10.1002/2211-5463.70071