Marine crabs are potential sources of new antibiotics as the circulating hemolymph contains biologically active substances such as complements, lectins, clotting factors and antimicrobial peptides. The present study was focused on evaluation of antimicrobial potential of the hemolymph and the lectin isolated from the hemolymph of marine crab Grapsus tenuicrustatus. The antimicrobial activity of crude hemolymph, clarified serum and purified lectin of the experimental crab was tested by disc diffusion method. The hemolymph exhibited higher activity than clarified serum and purified lectin. Maximum activity of 14 mm was recorded against Pseudomonas aeruginosa. Antimicrobial activity was also observed against other tested bacteria such as Bacillus subtilis, Staphylococcus aureus, Enterobacter aerogenes and E. coli. Among the fungal strains tested maximum activity of 13 mm and 15 mm was recorded with hemolymph and clarified serum against Aspergillus niger. The results indicate the antimicrobial efficiency of the hemolymph and the lectin and hence these would be considered as good source of antimicrobial agents and would replace the existing inadequate and cost effective antibiotics.
