476737 Engineering Yeast with Minicellulosome and Cellodextrin Pathway for Co-Utilization of Cellulose and Mixed Sugars

Friday, November 18, 2016: 10:00 AM
Continental 9 (Hilton San Francisco Union Square)
Li-Hai Fan, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, China

Consolidated bioprocessing (CBP), which integrates cellulase production, cellulose saccharification, and fermentation into one step, has been widely considered as the ultimate low-cost configuration for producing second-generation bioethanol from lignocellulose. However, the requirement of a microbial strain able to hydrolyze cellulosic biomass and convert the resulting sugars into high-titer ethanol limits CBP application. In this work, cellulolytic yeasts were developed by engineeringSaccharomyces cerevisiae with a heterologous cellodextrin utilization pathway and bifunctional minicellulosomes. The cell-displayed minicellulosome was two-scaffoldin derived, and contained an endoglucanase and an exoglucanase, while the intracellular cellodextrin pathway consisted of a cellodextrin transporter and a β-glucosidase, which mimicked the unique cellulose-utilization system in Clostridium thermocellum and allowed S. cerevisiae to degrade and use cellulose without glucose inhibition/repression on cellulases and mixed-sugar uptake. Consequently, only a small inoculation of the non-induced yeast cells was required to efficiently co-convert both cellulose and galactose to ethanol in a single-step co-fermentation process, achieving a high specific productivity of ~62.61 mg cellulosic ethanol/g cell·h from carboxymethyl cellulose (CMC) and ~56.37 mg cellulosic ethanol/g cell·h from phosphoric acid-swollen cellulose (PASC). Our work provides a versatile engineering strategy for co-conversion of cellulose-mixed sugars to ethanol by S. cerevisiae, and the achievements in this work may further promote the application of CBP in cellulosic biofuel production.

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See more of this Session: International Forum: Biotechnology in China
See more of this Group/Topical: Food, Pharmaceutical & Bioengineering Division