Edwardsiella tarda (Edwardsiellosis) is a serious problem to
the farming industry because the disease often occurs in fish
grown in farming ponds. E. tarda, a Gram-negative bacteria
belonging to the family of Enterobacteriaceae causes disease
in fish. E. tarda NG 8104 was isolated, for the first time, from
a flat-fish as a virulent pathogen in Japan. The use of antibiotics
to control the bacterial infection in fish is a concern
because it promotes the growth of drug-resistant bacterial
strains [9]. Lysozyme is widely distributed in fish at their
body, surface, skin, gill, intestinal tract, and serum as a protection
factor against bacterial infection [2]. The physical antimicrobial
action of lysozyme is suitable for use in aquaculture
because it may provide an effective approach to prevent bacterial
infection in fish without concern over residual antibiotics
in the fish. The purpose of the present paper was to investigate
the protective effect of orally administering
lysozyme-galactomannan or lysozyme-palmitic acid conjugates
to fish against a virulent strain of E. tarda.