An antimicrobial factor from the plasma of the horseshoe crab, Carcinoscorpius rotundicauda

Abstract

A bioactive component which was detected in the plasma of the Southeast Asian horseshoe crab, Carcinoscorpius rotundicauda was shown to be distinct from the antibacterial lectins isolated from its serum and the bactericidal tachyplesin peptides purified from the haemocytes. initial purificatio of the antimicrobial factor involved ultracentrifugation of the haemolymph and gel filtration through Sephadex G-100. The partially purified sample corresponds to a molecular weight of <2 kD. This semi-pure sample showed antibacterial effects on both Gram-positive and Gram-negative bacteria, particularly potent against the Klebsielleae tribe. Antifungal properties against yeast and filamentous fungi were also observed. Its antimicrobial effect was shown to be heat-resistant. Upon further purification by reverse phase HPLC, the potency of the antimicrobial againt against Klebsiella pneumoniae was increased at least 2-fold.