Abstract Detail

Poster Session

Mougharbel, Lina [1], Ostadjoo, Saghayegh [1], Lagu, Sonali [1], Martin, Vincent [1], Powlowski, Justin [1], Storms, Reginald [1].

Developing Consolidated Bioprocessing Competent Saccharomyces cerevisiae through the Optimized Expression of Fungal Cellulases.

Cellulose is the world's most abundant renewable carbon source. Presently, cellulosic ethanol production requires three reactors, one for the production of cellulase enzymes, one for the enzymatic hydrolysis of cellulose polymers into glucose, and another for the fermentation of glucose. In consolidated bioprocessing (CBP), cellulase enzyme production, hydrolysis and fermentation are carried out by a single microbe or a mixed stable culture in a single reaction vessel. Our goal is to engineer CBP-competent Saccharomyces cerevisiae strains for ethanol production. Towards this goal, we began by screening over 500 fungal cDNA and gDNA derived genes for β-glucosidases, endoglucanases (EGs) and cellobiohydrolases (CBHs) that could be functionally expressed in S. cerevisiae. The sequence of the coding regions of the top performing β-glucosidase, 5 best EGs and 3 best CBHs were optimized for expression in S. cerevisiae. The native signal peptides of the top performing enzymes were replaced with the Matα-pre or Matα-prepro signal peptide and the effect on expression levels compared with that of the native signal peptides. Expression levels were increased up to 16-fold and 10-fold by coding region optimization and signal peptide replacement, respectively. These 5 EGs were individually integrated into the yeast genome or expressed from a multi copy autonomously replicating plasmid using a strain that also expressed the β-glucosidase. Several S. cerevisiae transformants with integrated copies of the EGs were able to grow well on carboxymethylcellulose (CMC) as the sole carbon source. Presently we are integrating coding region optimized CBHs into several of the above yeast isolates that grew efficiently on CMC. Transformants harboring integrated copies of the CBHs will be screened for their ability to grow using pretreated cellulosic substrates as the sole carbon source.

1 - Concordia University, Department of Biology, 7141 Sherbrooke ST W, Montreal, QC, H4B 1R6, Canada

Keywords:
Consolidated bioprocessing
Saccharomyces cerevisiae
Fungal cellulases
Biofuels.

Presentation Type: Offered Paper - Poster
Session: P4
Location: Lincoln Room/Kellogg Hotel and Conference Center
Date: Tuesday, June 10th, 2014
Time: 8:00 PM
Number: P4006
Abstract ID:200
Candidate for Awards:Graduate Student Poster Presentation Award