Jørgensen Henning
Forest and Landscape Denmark, University of Copenhagen, Rolighedsvej 23, 1958 Frederiksberg, Denmark.
Appl Biochem Biotechnol. 2009 May;153(1-3):44-57. doi: 10.1007/s12010-008-8456-0. Epub 2008 Dec 18.
Wheat straw hydrolysate produced by enzymatic hydrolysis of hydrothermal pretreated wheat straw at a very high solids concentration of 30% dry matter (w/w) was used for testing the effect of nutrients on their ability to improve fermentation performance of Saccharomyces cerevisiae. The nutrients tested were MgSO4 and nitrogen sources; (NH4)2SO4, urea, yeast extract, peptone and corn steep liquor. The fermentation was tested in a separate hydrolysis and fermentation process using a low amount of inoculum (0.33 g kg(-1)) and a non-adapted baker's yeast strain. A factorial screening design revealed that yeast extract, peptone, corn steep liquor and MgSO4 were the most significant factors in obtaining a high fermentation rate, high ethanol yield and low glycerol formation. The highest volumetric ethanol productivity was 1.16 g kg(-1) h(-1) and with an ethanol yield close to maximum theoretical. The use of urea or (NH4)2SO4 separately, together or in combination with MgSO4 or vitamins did not improve fermentation rate and resulted in increased glycerol formation compared to the use of yeast extract. Yeast extract was the single best component in improving fermentation performance and a concentration of 3.5 g kg(-1) resulted in high ethanol yield and a volumetric productivity of 0.6 g kg(-1) h(-1).
由水热预处理的小麦秸秆在30%干物质（w/w）的极高固含量下酶解产生的小麦秸秆水解液，用于测试营养物质对其改善酿酒酵母发酵性能能力的影响。所测试的营养物质为MgSO4和氮源；硫酸铵、尿素、酵母提取物、蛋白胨和玉米浆。发酵在单独的水解和发酵过程中进行，使用少量接种物（0.33 g kg(-1)）和非适应性面包酵母菌株。析因筛选设计表明，酵母提取物、蛋白胨、玉米浆和MgSO4是获得高发酵速率、高乙醇产率和低甘油生成的最重要因素。最高体积乙醇生产率为1.16 g kg(-1) h(-1)，乙醇产率接近最大理论值。与使用酵母提取物相比，单独、一起使用尿素或硫酸铵，或与MgSO4或维生素组合使用，均未提高发酵速率，反而导致甘油生成增加。酵母提取物是改善发酵性能的最佳单一成分，3.5 g kg(-1)的浓度可实现高乙醇产率和0.6 g kg(-1) h(-1)的体积生产率。
