Abstract

The effects of two lignocellulose degradation by-products (furfural and acetic acid) on ethanol fermentations by six ethanologenic yeast strains were investigated. It was found that 1.5 g/l of furfural and 4.8 g/l of acetic acid, especially the latter, inhibited cell growth and increased ethanol yield, significantly. On the other hand, different yeast strains have different cell growth rate but very similar ethanol yield. This suggests that more attention should be put on finding strains with relatively high growth rate to enhance the bioethanol productivity. Among the tested yeast strains, 1300 exhibited the highest growth rate, thus can be a promising candidate for mass production of bioethanol. Three important operation parameters: temperature, pH value and inoculum size within investigated range (temperature 28 - 32°C; pH 4.5 - 6.5; and inoculum size 5 - 10%) did not significantly affect ethanol fermentation by strain 1300 with the existence of inhibitors furfural and acetic acid.

Key words: Lignocellulose degradation inhibitor, furfural, acetic acid, bioethanol, yeast.