PROTECTIVE EFFECT OF LYSOZYME-GALACTOMANNAN OR LYSOZYME-PALMITIC ACIDCONJUGATES AGAINST EDWARDSIELLA-TARDA INFECTION IN CARP, CYPRINUS-CARPIO L

The protective effect of lysozyme-galactomannan or lysozyme-palmitic a cid conjugates orally administered to carp, Cyprinus carpio L. was inv estigated using a virulent strain of Gram-negative Edwardsiella tarda isolated from an infected fish, Lysozyme-galactomannan conjugate was p repared through controlled Maillard reaction, Lysozyme-palmitic acid c onjugate was prepared through base-catalyzed ester exchange using N-hy droxysuccinimide ester of palmitic acid, The conjugates provided subst antial protection to carp infected with a Gram-negative bacteria fish pathogen E. tarda NG 8104, Lytic activities of lysozyme conjugates wit h galactomannan and palmitic acid were about 80 and 71% of native lyso zyme using Micrococcus lysodeikticus as a substrate, Feeding with lyso zyme conjugates, for 8 days, significantly enhanced fish protection ag ainst E. tarda infection, The survival rate was 30% for lysozyme-galac tomannan conjugate treated fish and 20% for lysozyme-palmitic acid con jugate treated fish after 6 days cultivation while all control fish di ed within 3 days, On the other hand, a recovery rate of 40% after 6 da ys was observed in the fish group that were fed lysozyme-palmitic acid conjugate 3 and 2 h before and after E. tarda challenge, respectively , and for 6 consecutive days, The results of this work show the possib ility of utilizing lysozyme conjugates with galactomannan or palmitic acid as a therapeutic for infection in fish.