Centro de Investigaciones Tecnológicas, Administración Nacional de Combustibles, Alcohol y Portland, (ANCAP), Pando, Canelones, C.P. 91000, Uruguay.
Biotechnol Bioeng. 1992 Oct 5;40(7):753-9. doi: 10.1002/bit.260400702.
Ethanol production was evaluated from eucalyptus wood hemicellulose acid hydrolysate using Pichia stipitis NRRL Y-7124. An initial lag phase characterized by flocculation and viability loss of the yeast inoculated was observed. Subsequently, cell regrowth occurred with sequential consumption of sugars and production of ethanol. Polyol formation was detected. Acetic acid present in the hydrolysate was an important inhibitor of the fermentation, reducing the rate and the yield. Its toxic effect was due essentially to its undissociated form. The fermentation was more effective at an oxygen transfer rate between 1.2 and 2.4 mmol/L h and an initial pH of 6.5. The hydrolysate used in the experiences had the following composition (expressed in grams per liter): xylose 30, arabinose 2.8, glucose 1.5, galactose 3.7, mannose 1.0, cellobiose 0.5, acetic acid 10, glucuronic acid 1.5, and galacturonic acid 1.0. The best values obtained were maximum ethanol concentration 12.6 g/L, fermentation time 75 h, fermentable sugar consumption 99% ethanol yield 0.35 g/g sugars consumed, and volumetric ethanol productivity 4 g/L day. (
利用毕赤酵母 NRRL Y-7124 从桉树木半纤维素酸水解物中生产乙醇。观察到酵母接种物初始的延迟阶段，其特征是絮凝和活力丧失。随后，随着糖的连续消耗和乙醇的生产，细胞重新生长。检测到多元醇的形成。水解物中存在的乙酸是发酵的重要抑制剂，降低了速率和产率。其毒性作用主要归因于其未离解形式。在氧传递速率为 1.2 至 2.4 mmol/L h 和初始 pH 值为 6.5 时，发酵效果更好。在实验中使用的水解物具有以下组成（以克/升表示）：木糖 30、阿拉伯糖 2.8、葡萄糖 1.5、半乳糖 3.7、甘露糖 1.0、纤维二糖 0.5、乙酸 10、葡萄糖醛酸 1.5 和半乳糖醛酸 1.0。获得的最佳值为最大乙醇浓度 12.6 g/L、发酵时间 75 h、可发酵糖消耗 99%、乙醇产率 0.35 g/g 消耗糖和体积乙醇生产率 4 g/L·天。
