الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
This investigation was carried out at the aim of the improvement of ethanol production in Saccharomyces cerevisiae via induced mutants and protoplast fusion techniques. Treatment with different doses of gamma irradiation and different concentrations of acriflavine was able to induce a decrease in viability percentage as dose and or concentration increases. In addition to , obtaining many auxotrophs and respiratory deficient mutants. Six fusions were carried out through protoplast fusion technique using seven variable strains where 47 fusants were obtained. The fusions Fu1, Fu3, Fu4 and Fu6 were successful in producing fusants which higher than their midparents in ethanol production indicating the success in the improvement of ethanol production. This represents the success of protoplast fusion as a method for genetic improvement of ethanol production in yeast. The relationship between consumed reducing sugars or invertase activity or hexokinase activity and ethanol production showed positive correlations at all conditions. An obvious genetic improvement of thermotolerance and ethanol production characters was induced successfully through gamma rays and acriflavine treatments. Protoplast fusion technique was proved to be a successful good tool inducing genetic improvement in thermotolerance and ethanol production characters. All selective fusants showed a higher total percent of nucleic acid than mid parents and some of them have a total nucleic acid percent very close to the twofold of midparents.