The study of the identification and purification of a novel antimicrobial peptide in the gills of the red banded grouper, Epinephelus fasciatus, a teleost fish, was investigated for the purpose of using compounds of the innate immunity in aquaculture and for anti-infective agents in animals. The purification procedure involved cation exchange chromatography and reverse phase HPLC followed by solid phase extraction on C18 Sep-Pak cartridges. The 50% of acetonitrile elutes (30 μg) caused a zone inhibition with a diameter of 0-16.4 mm depending on the salt concentration and the microbe tested. The Fourier transform infrared (FTIR) spectrum of epinisin in 50 mM sodium phosphate buffer was alpha-helix and ß-turn with tyrosine as amino acid side chains. The molecular mass of the antimicrobial factor was estimated to be approximately 72 kDa by SDS-PAGE. The antibacterial activity of the purified peptide was thermos table, remaining present even after incubation at 800C for 10 min. It can be concluded that epinisin showed a strong antimicrobial activity in vitro against a broad spectrum of microorganisms without significant hemolytic activity and was about 3 times more potent than magainin 2.
