Abstract:

The antimicrobial peptide was obtained from the body wall of Apostichopus japonicas and its activity was
evaluated. The crude peptide was extracted from the body wall with 5% acetic acid and subjected to bioassay-guided
fractionation for antimicrobial activity. The purification was completed by ultra-filtration and chromatographic separation
with macroporous resin. A turbidimetric method was applied to evaluate the inhibitory activity of each sample against
bacteria including Escherichia coli, Salmonella eternitidis, Staphylococcus aureus and Bacillus subtilis. By using Tricine-sodium
dodecyl sulfate-polyacrylamide gel electrophoresis (Tricine-SDS-PAGE), the molecular weight of the purified antimicrobial
peptide was measured. The results showed that three components with different molecular weights < 1 kD, 1–5 kD and 5–10 kD
were obtained after ultra-filtration. The component with molecular weight of < 1 kD had the strongest antibacterial activity, and
then it was chosen for further chromatographic separation with macroporous resin column. The subcomponent F3 with the highest
antimicrobial activity was obtained and its molecular weight was identified as 4.35 kD.

Key words: Apostichopus japonicas body wall, antimicrobial peptides, separation and purification, antimicrobial activity, turbidimetric method