Direct ethanol production from cellulosic materials at high temperature using the thermotolerant yeast Kluyveromyces marxianus displaying cellulolytic enzymes

作者：Yanase Shuhei; Hasunuma Tomohisa; Yamada Ryosuke; Tanaka Tsutomu; Ogino Chiaki; Fukuda Hideki; Kondo Akihiko^*

来源：Applied Microbiology and Biotechnology, 2010, 88(1): 381-388.

DOI：10.1007/s00253-010-2784-z

• Bioethanol
• Thermotolerant yeast
• Cellulose
• Cellulase
• Cell surface display
• Kluyveromyces marxianus

To exploit cellulosic materials for fuel ethanol production, a microorganism capable of high temperature and simultaneous saccharification-fermentation has been required. However, a major drawback is the optimum temperature for the saccharification and fermentation. Most ethanol-fermenting microbes have an optimum temperature for ethanol fermentation ranging between 28 degrees C and 37 degrees C, while the activity of cellulolytic enzymes is highest at around 50 degrees C and significantly decreases with a decrease in temperature. Therefore, in the present study, a thermotolerant yeast, Kluyveromyces marxianus, which has high growth and fermentation at elevated temperatures, was used as a producer of ethanol from cellulose. The strain was genetically engineered to display Trichoderma reesei endoglucanase and Aspergillus aculeatus beta-glucosidase on the cell surface, which successfully converts a cellulosic beta-glucan to ethanol directly at 48 degrees C with a yield of 4.24 g/l from 10 g/l within 12 h. The yield ( in grams of ethanol produced per gram of beta-glucan consumed) was 0.47 g/g, which corresponds to 92.2% of the theoretical yield. This indicates that high-temperature cellulose fermentation to ethanol can be efficiently accomplished using a recombinant K. marxianus strain displaying thermostable cellulolytic enzymes on the cell surface.

• 出版日期2010-9