F-2-Challenge test:
After 30 days of feeding, the fish were divided into three groups, first group; fish were fed on probiotic free
feed ∕ 30 days then experimentally infected (Intra-peritoneal injected) with Pseudomonas fluorescens (0.1 ml of
107 cells / ml), the second group; fish were fed on feed supplemented with probiotic L. plantarum ∕ 30 days then
challenged I/P with pathogenic Pseudomonas fluorescens (0.1 ml of 107 cells / ml). The third control group was
injected i.p. by 0.1 ml of saline.
All groups were kept under observation for 4 days to record the survival rates and clinical signs daily then
samples for biochemical and molecular analysis were collected.