Ethanol Production From Mixed Sugars By Mixed Yeasts
Dr. Jasim H. Neama , Hamsa E. Abdul-Wahed
Abstract

The study is aimed to improve ethanol production from mixed sugar dependency on mixed culture of isolated lactose -fermenting yeasts and baker's yeast ( Saccharomyces cerevisiae) under optimum condition of (sugars concentration,pH. The study was included: Studying the effect of sugar concentration and pH value in working of each yeast through making expirements for Ethanol and Biomass production from different concentrations of Individual sugars which constituents of Lactose sugar (Glucose and Galactose) by using Individual yeast(isolated from whey and S.cerevisiae) under different pH values and 35 °C for two days. Studying the working mechanisms of Individual yeast in synthetic media through making expirments by using this yeast for ethanol and biomass production from different concentrations of mixture sugars of (glucose and galactose) in equal ratio to that constituent of lactose sugar and from different concentration of synthetic Lactose under optimum determined pH5,35°C for two days. Studying the working mechanisms of yeasts in mix-culture through making expirments by using these yeasts for ethanol and biomass production from different mixture sugar concentrations, and synthetic Lactose by using mixture of S.cerevisiae and each of isolated yeasts, mixture of S.cerevisiae and all isolated yeasts, under same condisions. Obtained two Isolated yeast strains C.kyfer-T, and C.kyfer-S from crude whey. The optimum pH was pH5, S.cerevisiae significantly the best Ethanol and Biomass production from glucose, comparing with C.kyfer -T and C.kyfer-S, wich were the best in ethanol and biomass production from galactose, and C.kyfer-T was the best producer than C.kyfer-S. There are significantly increasing in ethanol production and significantly decreasing in biomass production from mixture , and significantly increasing in ethanol and biomass production from synthetic lactose , when using mix-culture of two C.kyfer (T-S) , co-culture of S.cerevisiae and each isolated yeast (C.kyfer )., mix-culture of ( S.cerevisiae, C.kyfer –T) produce(8.7)% ethanol from (10)% mixture, mix-culture of,( C.kyfer-S, C.kyfer –T) produced (4.6)% ethanol from(8)% synthetic lactose. There is significantly decreasing in ethanol and biomass production from mixture when using mix-culture of (S.cerevisiae + C.kyfer –T + C.kyfer-S) than using mix-culture of(S.cerevisiae + C.kyfer) and mix-culture of (C.kyfer –T + C.kyfer – S).