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Abstract
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Ethanol production can be increased by changing in dependent and independent parameters of medium. Therefore, the process of optimizing the medium is based on the interactions between the compounds of the medium and other factors involved in cell metabolism, which is carried out by an effective experiment design tool. In fractional factorial methodology such as Taguchi, with reducing the number of experiments, fraction of the complete factorial experiment is only performed. In this study, the growth rate of yeast and the amount of ethanol production were investigated in aerobic and aerobicanaerobic conditions. Selected Saccharomyces cerevisiae strain produced 8% of ethanol in molasses with brix18 at 29°C. Then, four factors of the medium, including molasses, urea, ammonium sulfate and pH, were selected in order to optimization by Taguchi method. After optimization, production of ethanol reached to 10% and 11% in flask and bioreactor culture, respectively. The results showed that nitrogen source has a significant effect on the production of ethanol by yeast under anaerobic conditions.
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