الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Yeast can secret antifungal substances named killer toxins which given very big important for biological control applications in the agri-food sectors of industry. Aflatoxins are a group of toxins of aflatoxin which naturally produced by Aspergillus flavus causing contamination of storage grains and feed. Five references strains of yeast: Schwanniomyces occidentalis (ATCC 2322); Kluyveromyces marxianus,(ATCC12708) and Kluyveromyces lactis,(ATCC 8585), Saccharomyces cerevisiae, (DBVPG 6499) ; Pichia anomala,(ATCC 121) and a reference strain of Aspergillus flavus (NRRL 32355) were used in current study . The ability of these references strains to production of killer toxin and for inhibition and elimination of aflatoxin production was examined by detection of β-1,3glucanase enzyme in vitro which could propose a mode of action for its antifungal activity. Results showed gradual decreases of fungus counts CFU/ml when Schwanniomyces occidentalis and/ or Pichia anomala was inoculated under flask condition. Scanning electron microscope examination showed that the examinnated yeast strains could colonize around the fungal hyphae leading to their lysis and deterioration. Aflatoxin % in the microbial cultural was determined through HPLC technique which revealed that (298 ppb) was produced from Aspergillus flavus while the values decreased to (zero ppb) after adding of Schwanniomyces occidentalis and (3 ppb) with P. anomala. The effect of Pichia anomala and Schwanniomyces occidentalis on the aflatoxin (in vivo) was evaluated through an experiment for about 30 days where treatments (T) with rats divided as follows: T1 was fed as basal diet (control), T2 the contaminated diet with aflatoxins (AF) at3ml suspension of fungi/1kg diet from T3:T10 were supplemented with different concentrations of yeasts. Results presented significant increases in nitrogen content 8.95 % and 8.93 % with T4 and T6 respectively in comparison to control treatment. Treatment (2) caused lower final body weight and total body weight gain and significantly higher mortality rate, kidney functions (creatinine and urea) and liver functions (AST, ALT and ALP). Histopathological changes in Liver, Kidney and spleen of toxin –treaded rat´s vacuolation of epithelial lining renal tubules, hydropic degemenration of hepatocytes and hemorrhage were also recorded. On the other hand, the treatments T3 to T8 had an improvement in performance as compared with T2 which showed significantly higher finally body weight, total body weight gain and lower mortality rate. No histopathological changes were observed in rat´s Kidney and spleen with samples that supplemented with yeast. The current study recommended the usage of yeast (Pichia anomala and Schwanniomyces occidentalis) or their mixture for inhibiting mold growth and it´s toxigenic effects in animal diets.