Novel Antimicrobial Peptide Sparadin118–140 from Scylla paramamosain Suppresses Pseudomonas Spoilage in Tilapia Fillets and Mitigates Pseudomonas Lipopolysaccharide-Induced Inflammation

Psychrotrophic Pseudomonas are the main spoilage bacteria in refrigerated aquatic products, but conventional preservatives are limited and fail to address the inflammatory risk of Pseudomonas lipopolysaccharide. We identified and synthesized Sparadin118–140, a 23-residue peptide within the Sparadin protein from Scylla paramamosain. It showed potent bactericidal activity against three Pseudomonas species via membrane disruption, retained activity at refrigeration temperature, and adopted an α-helical conformation. It inhibited biofilm formation and disrupted established biofilms. The peptide also suppressed P. aeruginosa LPS-induced inflammation in macrophages and zebrafish, reducing pro-inflammatory cytokines while upregulating IL-10, and showed favorable biocompatibility and stability under neutral pH, refrigeration, and thermal processing conditions. In preservation assays, it inhibited bacterial growth, retarded protein hydrolysis and lipid oxidation, and extended the shelf life of refrigerated tilapia fillets, with effects comparable to potassium sorbate. Thus, Sparadin118–140 is a multifunctional natural biopreservative against Pseudomonas spoilage and LPS-associated inflammatory hazards.