Evaluating the Antimicrobial Efficacy of TroLEAP2 like-27 peptide in golden pompano (Trachinotus ovatus) against Bacterial Pathogens.

Amicrobial peptides are crucial components of immune system, acting as the first line of defense against microbial invasion. This study investigated the antimicrobial activity of TroLEAP2 like-27, a novel 27-amino acid peptide derived from golden pompano (Trachinotus ovatus), against Gram-positive Lactococcus garvieae and Staphylococcus epidermidis, and Gram-negative Vibrio alginolyticus and Vibrio harveyi. The 3D structure and helical wheel presentation of TroLEAP2 like-27 were consistent with typical AMP features. The hydrophobic ratio of TroLEAP2 like-27 was 47 %, and its α-helical structure suggested strong antimicrobial potential. The expression levels of the TroLEAP2 like gene in the liver and intestines tissues of T. ovatus were significantly upregulated following infection with L. garvieae and V. harveyi. The peptide induced bacterial agglutination in the presence of Ca and exhibited bactericidal activity with a MIC of 60 μM. Transmission electron microscopy (TEM) revealed structural damage to bacterial membranes, while membrane permeability assays showed dose-dependent disruption and depolarization in all tested strains. Additionally, TroLEAP2 like-27 exhibited a potent capacity to interact with and degrade genomic DNA of all tested bacteria. The peptide treatment significantly reduced bacterial loads in the gill, liver, and intestinal tissues of the fish, with histological analysis revealing a remarkable protective effect on the tissues. Furthermore, fish treated with TroLEAP2 like-27 exhibited improved survival rates following bacterial infection. These findings suggest that TroLEAP2 like-27 is a promising antimicrobial peptide with potential therapeutic applications.