THE IMMUNOSTIMULANT EFFECT OF SACCHAROMYCES CEREVISIAE AND THE IMPACT OF FUSARIUM SOLANI INFECTION ON OREOCHROMIS NILOTICUS

Abstract

Abstract:This study summarizes the impact of Fusarium solani on Oreochromis niloticus with evaluation of the efficacy of Saccharomyces cerevisiae for decreasing its possible consequences on fish health was investigated. Fifty samples of fish ration were collected for isolation and identification of Fusarium solani. One hundred and sixty O. niloticus clinically healthy, average weight of 59.25±1.04 g was distributed into four groups. First group was a control negative group (C). Second group (F) was infected with Fusarium solani (1x 104 zoospores of Fusarium /ml). Third group (F+S) was fed a basal diet containing S. cervisaie 1 g/ kg ration daily and injected intraperitoneally with Fusarium solani. Fourth group (S) was fed a basal diet containing (S. cervisaie) daily. The experiment extended for five weeks then all groups were challenged with Pseudomonas aeroginosa (3x 107 CFU/ml). Bacteriological findings of the intestinal microbiota revealed significant increase (log10 CFU/ml) in total bacterial count (TBC) in the (F+S) group (4.51±0.012) and decreased gradually from the 1st week to the 5th week, while the (S) group showed slight increase in TBC than (C) group (P<0.05). The haemato-immunological parameters after 3 weeks in the (S) group showed significant increase in serum lysozyme activity and total leukocytic count. After five weeks there were a marked decrease in serum lysozyme activity and total leukocytic count in (F) group. After the challenge, there was a significant decrease in serum lysozyme activity and total leukocytic count in (F) group. Lymphocyte count and gamma globulin were significantly higher in (S) group than group (C) (P<0.05). The Pathological lesions in gills, liver, muscles in (F) group showed sever degenerative changes, necrosis and leucocytic infiltrations. The lesions in group (F+S) were milder. It could concluded that S. cerevisiae can be used in ration of O. niloticus under immune-depressive stressful condition (fungal infection) to increase their resistance.       Key words: Fusarium solani, Oreochromis niloticus, Saccharomyces cerevisiae, immunostimulants.