Résumé
The effect of frequent subculturing, freezing and lyophilization in presence of cryoprotectives on antagonistic activity and viability of saccharomyces boulardii was studied. Results indicated that early subculturings led to increasing the antagonistic activity but this activity fell down gradually and diminished after 10 -11 of subculturing which indicated the cytoplasmic responsibility i.e., could be coded by plasmids or virus-like particles. Freezing at -20°C had no effect on the viability in the presence of cryoprotectives like skim milk powder, Mg-stearate or without them, since the cultures recovered at 99-99.2% after [4] days. Lyophilization had very overt effect on viability .Skim milk provided the best protection [8% reduction] followed by using distilled water and Mg-stearate .Saline had the greatest effect and caused [15% reduction]. Storage results of lyophilized samples at room temperature and refrigerator showed that skim milk was the best at both temperatures followed by distilled water, saline and then Mg-stearate which showed the highest reduction in viable count of yeast