| Utilization of production of ethanol by lignocellulose is one of the important fermentation industrial, the major components of fine fiber hydrolysate are hexose and pentose. The technology of transforming hexose into ethanol has been more mature, while the yeasts which could assimilate pentose mostly can't produce ethanol by fermented pentose, and the yeasts could ferment pentose yield relatively lower ethanol. Therefore, in traditional ethanol fermentation process, the low ethanol concentration, the low material utilizing ratio, the low ethanol transformation efficiency and the high energy consumption resulted in poor production efficiency. Pentose fermentation is one of the key factors which could decide the economic feasible of producing ethanol from plant fiber. In addition, when the ethanol concentration accumulated to a certain value in fermentation process, this would have the poisonous effect to yeast cells. Moreover, different yeast strains had different resistance to a certain ethanol concentration, and on different culture conditions, the same yeast strain would have different resistance to a certain ethanol concentration. So fermenting at high ethanol tolerance is a hotspot on the study of fermentation industrial.Glucose and xylose could be fermented by Pachysolen tannophilus simultaneously. In order to investigate the effects of added inositol and NaCl on cell viability, ethanol production and ethanol tolerance of Pachysolen tannophilus, different concentrations of NaCl (0～0.15g·L-1) or inositol(0～0.20g·L-1)were added respectively in the media. Both of NaCl and inositol could protect yeast cell from harmful effect of high concentration ethanol. The results indicated that NaCl and inositol had remarkable effects on ethanol production and ethanol tolerance, but little on the growth of Pachysolen tannophilus. Furthermore, ethanol tolerance was more powerful when the yeast was cultured in YEPD medium than in YEPX medium. It was found that, there were more yeast biomass and more ethanol production in the presence of NaCl and inositol than without them. With the addition of initial ethanol, the most appropriate concentrations of NaCl and inositol for yeast fermentation were 1.50g·L-1 and 0.10g·L-1, while the ethanol production yield were 40.12 g·L-1 and 45.20 g·L-1, respectively. The more added NaCl and inositol, the more ethanol was produced when the fermentation medium contained 10% or 12% initial ethanol. And the maximum ethanol concentrations were10.16g·L-1 and 9.87g·L-1 fermented by NaCl addition, and 17.18g/L and 16.68g/L by inositol addition with the same formula. It is revealed that inositol plays a more important role in ethanol production and ethanol tolerance than NaCl. |
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