Chemo-enzymatic production of fuel ethanol from cellulosic materials utilizing yeast expressing beta-glucosidases.
Ethanol was produced in a considerably high yield by fermenting hydrolyzates from cellulosic materials by means of a recombinant laboratory yeast expressing beta-glucosidases. Tissue paper, cotton, and sawdust were hydrolyzed by two-step sulfuric acid hydrolysis to give mixtures containing glucose, cellobiose, and higher cello-oligosaccharides. After the cellulosic material was partially hydrolyzed with 80% sulfuric acid, the hydrolysis was continued with 5% sulfuric acid. Except for non-carbohydrate components, all constituents in the hydrolyzates were fermented by the yeast that was preincubated in the medium that the plasmid encoded by the beta-glucosidases gene was kept in the multiplicated yeast. A solution containing 4% hydrolyzates from paper was fermented to give as high as 1.9% maximum ethanol concentration and 70% ethanol conversion. Cotton also gave a similar result. Sawdust was converted into ethanol in approx 22% conversion. Accordingly, it was revealed that the beta-glucosidases-expressing yeast can ferment the cello-oligosaccharides obtained by hydrolysis of cellulosic materials into ethanol. In addition, a hydrolyzate containing a high glucose proportion gave a high ethanol concentration in a short time.
Uryu
Toshiyuki
T
Department of Environmental and Material Engineering, Teikyo University of Science and Technology, 2525 Yatsusawa, Uenohara, Yamanashi 409-0193, Japan. uryu@ntu.ac.jp
Sugie
Masashi
M
Ishida
Satoshi
S
Konoma
Shinya
S
Kato
Hironori
H
Katsuraya
Kaname
K
Okuyama
Kohsaku
K
Borjihan
Gereltu
G
Iwashita
Kazuhiro
K
Iefuji
Haruyuki
H
D001230:Aspergillus / Q000201:enzymology; D001709:Biotechnology / Q000379:methods*; D002241:Carbohydrates / Q000737:chemistry; D002244:Carbon / Q000737:chemistry; D002482:Cellulose / Q000737:chemistry*; D004736:Energy-Generating Resources; D000431:Ethanol / Q000737:chemistry*; D005285:Fermentation; D005742:Gasoline; D005947:Glucose / Q000378:metabolism; D006868:Hydrolysis; D008956:Models, Chemical; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D013464:Sulfuric Acids / Q000737:chemistry; D001617:beta-Glucosidase / Q000096:biosynthesis* / Q000737:chemistry
D002241:Carbohydrates; D005742:Gasoline; D013464:Sulfuric Acids; D000431:Ethanol; D002244:Carbon; D002482:Cellulose; D001617:beta-Glucosidase; D005947:Glucose; C033158:sulfuric acid