الفهرس 
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Abstract
In aquaculture, Pseudomonas spp. (P. fluorescens, P. putida and P. aeruginosa) were incorporated in severe outbreaks in intensive earthen ponds. P. fluorescens has been associated with septicemia and ulcerative conditions in wide range of fishes. The prevalence of Pseudomonas species in marine fishes accompanied by bad water quality and heavy metals as well as immune parameters associated with these infections. Therefore, we have to explore this field to know how we can protect the Egyptian Mariculture fish against Pseudomonas species .
In our study, a total number of 200 of two species of cultured marine fishes of different body weight range; 100 sea bass and 100 of sea bream. Fishes were collected showing clinical signs from two locality; Mathalath El-Diba at Domitte governorate, Egypt and Borg El-Arab, Mariut valley region, Alexandria governorate, Egypt during winter season.
After culture on media and biochemical reactions, the incidence of different Pseudomonas species in different organs in infected sea bass and sea bream in Mathalath El-Diba was; P. fluorescens; P. aeruginosa; P. anguilliseptica; P. putida; P. stutzeri; P. mendocina; P. alcaligenes and Pseudomonas sp. I want to stated that the P. fluorescens and P. aeruginosa was the predominant bacteria isolated from different organs specially gills and liver of infected sea bass and sea bream in Mathalath El-Diba area .
PCR method used for detection of 7 P. aeruginosa isolates from diseased sea bass (D. labrax L.) and sea bream (S. aurata L.) that are considered positive as P. aeruginosa and contain toxR gene when visible band appeared at 956 bp. On the other hand, the bacterial strains used in the primer specificity studies are comprises 5 P. fluoresnce isolates from diseased sea bass and sea bream that are considered positive as P. fluoresnce and contain 16S rDNA gene when visible band appeared at 800 bp which is used after that for experimental infection.
During the bacteriological examinations, Water samples were taken for determination of water quality and heavy metal concentrations in water samples using spectrophotometric methods and then we made comparison with permissible levels in water for marine culture
Experimental infection : A total number of one hundred and forty (140) of apparently healthy from both sea bass and sea bream were used. The fish were left for acclimation to the laboratory conditions for two weeks prior to the experiment was carried out.
* Results revealed that :
1) The LD50 of the injected of P. aeruginosa in sea bass and sea bream were 2.0×104 CFU ml-1 and 2.0×103 CFU ml-1, while the LD50 of the injected of P. fluoresnce in sea bass and sea bream were 2.0×105 CFU ml-1 and 2.0×104 CFU ml-1.
2) The results of pathogenicity test of P. aeruginosa and P. fluoresnce in sea bass and sea bream showed that the mortality % of injected of P. aeruginosa and P. fluoresnce in sea bass and sea bream with 2.0×104 CFU ml-1 and 2.0×103 CFU ml-1 from P. aeruginosa in sea bass and sea bream and 2.0×105 CFU ml-1 and 2.0×104 CFU ml-1 from P. fluoresnce in sea bass and sea bream the mortality % were 90; 80; 80 and 70 respectively; and on the other side the mortality % of injected saline were 0.0%.
3) Clinico-biochemicals parameters revealed that the total protein and globulin were markedly decreased compared with control non-infected sea bass and sea bream. And markedly increased of the AST and ALT were in experimentally infected sea bass and sea bream by P. aeruginosa and P. fluoresnce compared with control.
Histopathological alterations revealed that; the liver of sea bass infected with P. aeruginosa showing multifocal areas of necrosis in hepatic infected with P. fluoresnce showing wide area of necrosis in hepatopancreas with activation of melano-macrophage centers. Liver of sea bream infected with P. aeruginosa showing polygonal shaped cells and congested blood vessels and hepatic sinusoids and when infected with P. fluoresnce showing degenerative changes in hepatopancreas and hepatic tissue.
Kidney of sea bass infected with P. aeruginosa showed sever hemorrhage, damage and necrosis of renal tissue and when infected with P. fluoresnce showed degeneration of tubular epithelial mononuclear cell infiltration between renal tubules. Kidney of sea bream infected with P. aeruginosa showed destruction and desquamation of tubular epithelial while infected with P. fluoresnce showed necrosis of tubular epithelial with presence of tubular hyaline cast. Spleen of sea bream infected with P. fluoresnce showed severs hemorrhages and hemosiderin-phages .