C13 | Prototype antimicrobial peptide-based sanitiser: new horizons in the post-antibiotic era

R.L. Ambrosio, V. Vuoso, G. Fiore, B. Testa, N. Murru, A. Anastasio. | Dip. di Medicina Veterinaria e Produzioni Animali dell’Università degli studi di Napoli “Federico II”.

Purpose. The aim of this study was to develop a prototype of an environmentally friendly, effective and sustainable antimicrobial peptide-based disinfectant designed to reduce the persistence of pathogenic and spoilage bacteria throughout the dairy supply chain. Methods. The antimicrobial peptide BC_1, previously designed and characterised in silico, was tested in vitro against coagulase-positive and coagulase-negative staphylococci, including pathogenic strains (such as methicillin-resistant Staphylococcus aureus) and spoilage bacteria, to evaluate its antimicrobial activity (broth micro-dilution method) and anti-biofilm activity (crystal violet assay). Spectroscopic analyses were also performed to evaluate the conformational stability of the peptide over a wide range of temperatures (5 to 90°C) and pH values (2 to 9). Finally, to determine its antimicrobial efficacy, the prototype sanitiser was tested on a contaminated surface (3 Log (CFU/cm²); challenge test) with a bacterial polyculture composed of bacterial strains isolated from milking equipment (Staphylococcus hyicus, S. chromogenes, Streptococcus parauberis). Surface sampling was performed post-treatment, leaving the aqueous peptide solution to act for 10 seconds, 1 minute or 10 minutes. Results. The antimicrobial peptide BC_1 showed antibacterial and anti-biofilm activity at low concentrations (9-75 μM) against the bacterial strains tested. The transition temperature (T_m) was determined to be approximately 81.82°C and the estimated pKa was approximately 10.25. In addition, the prototype water-based sanitiser, used at a peptide concentration of 50 μM, significantly reduced surface contamination (3 Log (CFU/cm²)) by 98.35%, 99.67% and 99.78% with contact times of 10 seconds, 1 minute and 10 minutes, respectively. Conclusions. Stability tests confirmed the suitability of the peptide for inclusion in biosanitising formulations, while antimicrobial and anti-biofilm assays demonstrated its potential even at very low concentrations, as corroborated by a simulation study. Antimicrobial peptides, such as BC_1, are known to selectively interact with prokaryotic cell membranes, inducing their permeabilisation, and inhibit the production of the extracellular matrix. These results open up interesting and promising prospects, as the use of BC_1 could help alleviate the pressure of antimicrobial resistance and tolerance in the agri-food industries. In the current post-antibiotic era, antimicrobial peptides could represent a valid alternative to common antimicrobials; therefore, the benefits and critical issues of their use must be carefully and thoroughly evaluated.