Simultaneous saccharification and fermentation of acid-pretreated corncobs with a recombinant Saccharomyces cerevisiae expressing beta-glucosidase

Bioresour Technol. 2008 Jul;99(11):5099-103. doi: 10.1016/j.biortech.2007.09.046. Epub 2007 Oct 31.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acids
  • Cellobiose / metabolism
  • DNA, Recombinant / genetics*
  • Ethanol / metabolism
  • Fermentation*
  • Genetic Vectors
  • Glucose / metabolism
  • Oligosaccharides / metabolism*
  • Plasmids
  • Saccharomyces cerevisiae / enzymology*
  • Saccharomyces cerevisiae / genetics*
  • Zea mays / metabolism*
  • beta-Glucosidase / metabolism*

Substances

  • Acids
  • DNA, Recombinant
  • Oligosaccharides
  • Cellobiose
  • Ethanol
  • beta-Glucosidase
  • Glucose