Studies On Molecular Design And Bactericidal Activity Of Antimicrobial Peptides Based On Large Yellow Croaker (Larimichthys Crocea) Macroh2a1 Protein Sequences

In recent years,with the rapid development of aquaculture,the outbreak of aquatic animal diseases has restricted the development of this industry.In the process of prevention and treatment of bacterial diseases in aquaculture animals,the problems of bacterial resistance and drug residues caused by long-term use and uncontrolled abuse of antibiotics seriously threaten human health.In this study,antibacterial peptide RMR26 and its derivatives VYR13 and VIK14 were synthesized by using the macroh2a1 protein sequence of large yellow croaker as a template.The antibacterial activity,physicochemical properties,cytotoxicity,hemolytic activity,and bactericidal mechanism of three antimicrobial peptides were investigated.The minimum inhibitory concentration(MIC)and minimum bactericidal concentration(MBC)of RMR26,VYR13,and VIK14 were determined by the double gradient dilution method and colony counting method,respectively.The results showed that different peptides had a broad-spectrum antibacterial effect,the antibacterial effect of VYR13 and VIK14 was better than that of RMR26,and the antibacterial range was wider.Subsequently,we used Pseudomonas plecoglossicida as indicator bacteria to investigate the effects of temperature,p H,and protease on the antibacterial activity of different peptides.The results showed that temperature and p H had no effect on the antibacterial activity of peptides RMR26,VYR13,and VIK14,but the antibacterial activity of peptides decreased after protease treatment.The cytotoxicity and hemolytic activity of the peptides were detected by LYC-FM cells and red blood cells in large yellow croakers.The results showed that the peptides RMR26,VYR13,and VIK14 had low cytotoxicity and hemolytic activity,and had good safety.Finally,we explored the antibacterial mechanism of RMR26.The results showed that RMR26 could penetrate the cell wall of Pseudomonas plecoglossicida,destroy the integrity of the cytoplasmic membrane,and cause the change of morphological structure of Pseudomonas plecoglossicida.In addition,RMR26 is mainly involved in the killing effect of Pseudomonas plecoglossicida with α-helix structure.