Department of Biotechnology, Engineering College of Lorena, University of São Paulo, Lorena, SP, Brazil.
Yeast. 2011 Jul;28(7):547-54. doi: 10.1002/yea.1858. Epub 2011 May 30.
The ability of a recently isolated Scheffersomyces stipitis strain (UFMG-IMH 43.2) to produce ethanol from xylose was evaluated. For the assays, a hemicellulosic hydrolysate produced by dilute acid hydrolysis of sugarcane bagasse was used as the fermentation medium. Initially, the necessity of adding nutrients (MgSO(4)·7H(2)O, yeast extract and/or urea) to this medium was verified, and the yeast extract supplementation favoured ethanol production by the yeast. Then, in a second stage, assays under different initial xylose and cell concentrations, supplemented or not with yeast extract, were performed. All these three variables showed significant (p < 0.05) influence on ethanol production. The best results (ethanol yield and productivity of 0.19 g/g and 0.13 g/l/h, respectively) were obtained using the hydrolysate containing an initial xylose concentration of 30 g/l, supplemented with 5.0 g/l yeast extract and inoculated with an initial cell concentration of 2.0 g/l. S. stipitis UFMG-IMH 43.2 was demonstrated to be a yeast strain with potential for use in xylose conversion to ethanol. The establishment of the best fermentation conditions was also proved to be of great importance to increasing the product formation by this yeast strain. These findings open up new perspectives for the establishment of a feasible technology for ethanol production from hemicellulosic hydrolysates.
评估了最近分离出的毕赤酵母（UFMG-IMH 43.2）菌株从木糖生产乙醇的能力。对于这些测定，使用通过甘蔗渣稀酸水解产生的半纤维素水解物作为发酵培养基。最初，验证了向该培养基中添加营养物质（MgSO4·7H2O、酵母提取物和/或尿素）的必要性，并且酵母提取物的添加有利于酵母生产乙醇。然后，在第二阶段，在补充或不补充酵母提取物的情况下，在不同的初始木糖和细胞浓度下进行了测定。这三个变量都对乙醇生产有显著影响（p<0.05）。在使用含有初始木糖浓度为 30 g/l、补充 5.0 g/l 酵母提取物并接种初始细胞浓度为 2.0 g/l 的水解物的情况下，获得了最佳结果（乙醇产率和生产力分别为 0.19 g/g 和 0.13 g/l/h）。证明 S. stipitis UFMG-IMH 43.2 是一种具有将木糖转化为乙醇潜力的酵母菌株。建立最佳发酵条件也被证明对提高该酵母菌株的产物形成非常重要。这些发现为建立可行的从半纤维素水解物生产乙醇的技术开辟了新的前景。
