Survey of the inhibitory effect on growth and ethanol yield in the fermentation process of baker’s yeast Saccharomyces cerevisiae

Abstract

Introduction: The use of hydrolysis process in order to release reducing sugars of Polysaccharide materials for ethanol production, especially in acid hydrolysis process, causes the produce growth inhibitors compounds such as furfural and hydroxymethyl. Existing these compounds in culture medium, in addition to decrease microorganism growth and glucose consumption they cause the decrease efficiency of ethanol production. Materials and methods: In order to investigate the effect of both inhibiting compounds hydroxymethyl furfural and furfural on growth, glucose consumption and ethanol production by Saccharomycescerevisiae yeast, four field experiments with different concentrations include 0orcontrol0.5, 1 and 2gl-1of each compound was prepared, and their inhibitory effects on yeast growth and ethanol production was studied in during 36 h. Results: The results showed that with increasing concentration hydroxymethyl furfural and furfural, both compounds have inhibitory effect on growth yeast, glucose consumption and ethanol production, so that the maximum efficiency of ethanol production for two compounds (hydroxymethylfural and furfural), were observed at concentrations of 0 or control and 0.5 gl-1.The results showed that the furfural compound in comparison to hydroxymethylfural have more inhibitory effect on Saccharomycescerevisiae growth and ethanol production by it. Discussion and conclusion: In general decrease in glucose consumption by increasing concentrations of these compounds showed the negative effects of these compounds on the growth and metabolism yeast, and therefore the ethanol production is reduced.

Keywords

• Ethanol
• Cell biomass
• Furfural
• Hydroxymethyl fural
• Saccharomyces cerevisiae