Inhibitory effect of an antimicrobial peptide A7 on Vibrio spp. and its application in Apostichopus japonicus

To address the growing prevalence of bacterial diseases in sea cucumber farming and the safety concerns and antibiotic resistance issues arising from inappropriate antibiotic use, we evaluated the inhibitory effect and application potential of antimicrobial peptide (AMPs) A7 against Vibrio and its effectiveness in removing Vibrio from the aquaculture water of sea cucumber (Apostichopus japonicus). The antibacterial profile of A7 was determined by the Oxford cup antibacterial coil method and 96-well microtiter plates with 30 strains of Vibrio as the indicator bacteria. Thereafter, a pond trial was conducted to investigate different water concentrations of A7 (0, 3, 5 and 10 mg·L⁻¹ water in pond) in A. japonicus breeding pool. And Vibrio counts changes in water at 0^th, 24^th and 48^th hour were measured. The results show that A7 had inhibitory effects on 30 strains of Vibrio in the experiment, and the inhibitory effect on V. splendidus was best, with an average inhibition zone diameter of 25.3 mm and a minimum inhibitory concentration (MIC) of 97 mg·L⁻¹. However, the effective dose in the pond was much lower than the MIC determined in the laboratory. Using 3–10 mg·L⁻¹ antimicrobial peptide A7 had a good removal effect on Vibrio in sea cucumber ponds, and the higher the dose used, the faster the onset of effect and the higher the removal rate of Vibrio. In conclusion, antimicrobial peptide A7 shows broad spectrum bacteriostasis against Vibrio from aquatic aquaculture environment and holds promising prospects for prevention and control applications.