Simultaneous saccharification and fermentation of acid-pretreated corncobs with a recombinant Saccharomyces cerevisiae expressing beta-glucosidase.
To reduce the cellobiose inhibition of exoglucanase and endogulcanase and enhance cellulose hydrolysis during simultaneous saccharification and fermentation (SSF), a beta-glucosidase encoding gene named BGL1 was cloned from Saccharomycopsis fibuligera and integrated into the chromosomal rDNA region of the Saccharomyces cerevisiae industrial strain NAN-27 producing NAN-227. Compared with the parental strain, which had no detectable activity, the beta-glucosidase specific activity in NAN-227 was 1.02 IU/mg of protein. When cellobiose was used as the sole carbon source in a shake-flask, NAN-227 consumed 6.2g/L of cellobiose and produced 3.3g/L of ethanol in 48 h. The yield was 0.532 g/g. The parent strain only consumed 1.92 g/L of cellobiose and no ethanol was detected. During the SSF of acid-pretreated corncobs NAN-227 produced 20 g/L of ethanol at 72 h, which was similar to the parent strain when 20IU of beta-glucosidase/g of substrate was added.
Shen
Yu
Y
State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, PR China.
Zhang
Yan
Y
Ma
Tao
T
Bao
Xiaoming
X
Du
Fengguang
F
Zhuang
Guoqiang
G
Qu
Yinbo
Y
D000143:Acids; D002475:Cellobiose / Q000378:metabolism; D004274:DNA, Recombinant / Q000235:genetics*; D000431:Ethanol / Q000378:metabolism; D005285:Fermentation; D005822:Genetic Vectors; D005947:Glucose / Q000378:metabolism; D009844:Oligosaccharides / Q000378:metabolism*; D010957:Plasmids; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics*; D003313:Zea mays / Q000378:metabolism*; D001617:beta-Glucosidase / Q000378:metabolism*
D000143:Acids; D004274:DNA, Recombinant; D009844:Oligosaccharides; D002475:Cellobiose; D000431:Ethanol; D001617:beta-Glucosidase; D005947:Glucose