Sunday, April 29, 2007
1B-22
Utilization of cellobiose by Saccharomyces cerevisiae strains harboring intracellular b-glucosidase and cellobiose phosphorylase
Christa Sadie, Rončl van Rooyen, and Willem H van Zyl. Microbiology, University of Stellenbosch, Stellenbosch, 7600, South Africa
Saccharomyces cerevisiae cannot utilize the abundant polymer, cellulose, as an energy source. Several β-glucosidases have been introduced in S. cerevisiae enabling it to utilize cellobiose, the building disaccharide of cellulose for the production of ethanol. We will report the expression of an intracellular cellobiose phosphorylase (CbP) and β-glucosidase (BGL) in S. cerevisiae for the first time. Cellobiose phosphorylase cleaves and subsequently phosphorylates cellobiose, possibly having a metabolic advantage over the hydrolysis of cellobiose by β-glucosidase. The secretion signal from a fungal β-glucosidase was removed and expressed constitutively from a multi-copy yeast expression vector S. cerevisiae SIGMA strain, designated (SIGMA[BGL]). Similarly, the intracellular cellobiose phosphorylase was expressed in a S. cerevisiae CEN.PK 21-C strain (CEN.PK[CbP]). Aerobic batch cultivation of the adapted SIGMA[BGL] and CEN.PK[CbP] strains showed an improved growth rate of 0.09 h-1 and 0.07 h-1 in 10 g/L cellobiose, respectively. RNA Bio-Dot results revealed the induction of native transporters in the adapted SIGMA[BGL] strain, capable of transporting and utilizing cellobiose intracellularly.
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See more of The 29th Symposium on Biotechnology for Fuels and Chemicals (April 29 - May 2, 2007)
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See more of The 29th Symposium on Biotechnology for Fuels and Chemicals (April 29 - May 2, 2007)