Ethanol production from cellulosic materials using cellulase-expressing yeast.
We demonstrate direct ethanol fermentation from amorphous cellulose using cellulase-co-expressing yeast. Endoglucanases (EG) and cellobiohydrolases (CBH) from Trichoderma reesei, and beta-glucosidases (BGL) from Aspergillus aculeatus were integrated into genomes of the yeast strain Saccharomyces cerevisiae MT8-1. BGL was displayed on the yeast cell surface and both EG and CBH were secreted or displayed on the cell surface. All enzymes were successfully expressed on the cell surface or in culture supernatants in their active forms, and cellulose degradation was increased 3- to 5-fold by co-expressing EG and CBH. Direct ethanol fermentation from 10 g/L phosphoric acid swollen cellulose (PASC) was also carried out using EG-, CBH-, and BGL-co-expressing yeast. The ethanol yield was 2.1 g/L for EG-, CBH-, and BGL-displaying yeast, which was higher than that of EG- and CBH-secreting yeast (1.6 g/L ethanol). Our results show that cell surface display is more suitable for direct ethanol fermentation from cellulose.
Yanase
Shuhei
S
Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Nada, Kobe, Japan.
Yamada
Ryosuke
R
Kaneko
Shohei
S
Noda
Hideo
H
Hasunuma
Tomohisa
T
Tanaka
Tsutomu
T
Ogino
Chiaki
C
Fukuda
Hideki
H
Kondo
Akihiko
A
D001230:Aspergillus / Q000201:enzymology; D001674:Bioelectric Energy Sources; D002480:Cellulase / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D002482:Cellulose / Q000378:metabolism*; D043366:Cellulose 1,4-beta-Cellobiosidase / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D000431:Ethanol / Q000378:metabolism*; D007700:Kinetics; D010756:Phosphoric Acids / Q000737:chemistry; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D014242:Trichoderma / Q000201:enzymology
D010756:Phosphoric Acids; D011994:Recombinant Proteins; D000431:Ethanol; D002482:Cellulose; C030242:phosphoric acid; D002480:Cellulase; D043366:Cellulose 1,4-beta-Cellobiosidase