Simultaneous saccharification and fermentation of corncobs with genetically modified Saccharomyces cerevisiae and characterization of their microstructure during hydrolysis.
Cellulose is an abundant natural polysaccharide that is universally distributed. It can be extracted from corncobs, which are inexpensive, easily accessible, renewable, and environmentally friendly. A common strategy for effectively utilizing cellulose is efficient heterogeneous expression of cellulase genes in Saccharomyces cerevisiae. However, the improvement of cellulose utilization is a relevant issue. Based on our previous findings, we constructed an integrated secretion expression vector, pHBM368-pgk, containing a constitutive promoter sequence. Three genetically modified S. cerevisiae strains containing heterologous β-glucosidase, exoglucanase, and endoglucanase genes were constructed. The results of a 1-L bioreactor fermentation process revealed that the mixed recombinant S. cerevisiae could efficiently carry out simultaneous saccharification and fermentation (SSF) by using corncobs as the sole carbon source. The ethanol concentration reached 6.37 g/L after 96 hours of fermentation, which was about 3 times higher than that produced by genetically modified S. cerevisiae with the inducible promoter sequence. To investigate the microstructure characteristics of hydrolyzed corncobs during the fermentation process, corncob residues were detected by using a scanning electron microscope. This study provides a feasible method to improve the effect of SSF using corncobs as the sole carbon source.
a Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University , Wuhan , P. R. China.|b Hubei Key Laboratory of Regional Development and Environmental Response , College of Resources and Environmental Science, Hubei University , Wuhan , P. R. China.
Hui-Ting
HT
Song
a Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University , Wuhan , P. R. China.
Shi-Hui
SH
Liu
a Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University , Wuhan , P. R. China.
Yuan
Y
Gao
a Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University , Wuhan , P. R. China.
Yi-Min
YM
Yang
a Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University , Wuhan , P. R. China.
Wen-Jing
WJ
Xiao
a Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University , Wuhan , P. R. China.
Wu-Cheng
WC
Xia
a Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University , Wuhan , P. R. China.
Zi-Lu
ZL
Liu
a Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University , Wuhan , P. R. China.
Rong
R
Li
a Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University , Wuhan , P. R. China.
Xiang-Dong
XD
Ma
a Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University , Wuhan , P. R. China.|c Hubei Key Laboratory of Industrial Biotechnology , College of Life Science, Hubei University , Wuhan , P. R. China.
Zheng-Bing
ZB
Jiang
D019149:Bioreactors; D002480:Cellulase / Q000235:genetics* / Q000378:metabolism; D043366:Cellulose 1,4-beta-Cellobiosidase / Q000235:genetics* / Q000378:metabolism; D000431:Ethanol / Q000378:metabolism; D005285:Fermentation; D005818:Genetic Engineering; D005822:Genetic Vectors / Q000737:chemistry / Q000378:metabolism; D030781:Organisms, Genetically Modified; D011401:Promoter Regions, Genetic; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D019076:Transgenes; D014866:Waste Products; D003313:Zea mays / Q000378:metabolism* / Q000648:ultrastructure; D001617:beta-Glucosidase / Q000235:genetics* / Q000378:metabolism
D014866:Waste Products; D000431:Ethanol; D001617:beta-Glucosidase; D002480:Cellulase; D043366:Cellulose 1,4-beta-Cellobiosidase
bioethanol; cellulase; corncobs; fermentation; hydrolysis characteristic; simultaneous saccharification