Lysozyme from rainbow trout, Salmo gairdneri Richardson, as an antibacterial agent against fish pathogens

Abstract. The antibacterial effect of two lysozyme variants purified from rainbow trout, Salmo gairdneri Richardson, kidney was investigated as part of a project directed towards increasing the disease resistance of fish by the transgenic technique. Seven bacterial strains from five Gram-negative species, of which one was considered non-pathogenic, were examined. One of the rainbow trout lysozymes was surprisingly potent, having substantial antibacterial activity on all strains tested. Hen egg-white lysozyme was bactericidal only against the one species considered non-pathogenic. The data suggest that lysozyme does play a role in the disease defence of rainbow trout and that the gene for the most active lysozyme may be suitable for testing the transgenic strategy.