Pathogenicity, serum resistance activity and serological relatedness of pseudomonas fluorescens strains recovered from diseased preochromis niloticus in Egypt

ABSTRACT

Pseudomonas fluorescens [Ps. fluorescens] strains recovered from diseased Oreochromis niloticus [O. niloticus] were studied for their pathogenicity, scrum resistance activities and serological relatedness. The results of experimental pathogenicity in O, niloticus varied and generally ranged from acute septicaemic course to mild slow developing one or even none, suggesting the existence of variable virulence profiles among Ps. fluorescens strains. A correlation was found between serum resistance activity of Ps. fluorescens strains and their corresponding degrees of pathogenicity and virulence profiles as proved by the presence of a shared common resistance to the killing effect of O. niloticus serum among the highly pathogenic virulent strains. In addition, heterogenecity among Ps. fluorescens strains was biochemically and sero logically proved