An engineered Saccharomyces cerevisiae for cost-effective lignocellulosic bioethanol production: process performance and physiological insights
Poster (konferens), 2015

The success in the commercialization of lignocellulosic bioethanol relies on the development of microorganisms with efficient hexose and pentose fermentation and tolerance towards inhibitory by-products (acetic acid, furan aldehydes and phenolics) generated during biomass processing. Traditionally, the yeast Saccharomyces cerevisiae is the preferred microorganism for industrial ethanol production. Many years of research and development have been conducted to develop S. cerevisiae strains suitable for fermenting lignocellulosic-based streams. S. cerevisiae is robust and ferment glucose efficiently, but it has been proved to be difficult to genetically modify for efficient xylose fermentation. In this work, a xylose-fermenting S. cerevisiae strain was subjected to evolutionary engineering, boosting its robustness and xylose fermentation capacity. The evolved strain was able to ferment a non-diluted enzymatic hydrolysate (representing 23% (w/w) dry matter of steam-exploded wheat straw), reaching ethanol titers higher than 5% (w/w) after 48 h. Within the first 24 h, glucose and xylose were co-consumed with rates of 3.1 and 0.7 g/L h, respectively, and converted to ethanol with yields corresponding to 93% of the theoretical. In addition, once glucose was depleted, xylose was consumed with a similar rate until reducing 70% of its initial concentration (36 h after inoculation). Besides investigating the fermentation parameters, the differences in gene expression levels and enzymatic activities of xylose-assimilating pathway were analyzed. These analyses will be the foundation for understanding the improved phenotype and the physiological mechanisms for efficient xylose fermentation, after which potential targets for subsequent metabolic engineering may be identified.

Författare

David Moreno

Chalmers, Biologi och bioteknik, Industriell bioteknik

Elia Tomas-Pejo

Chalmers, Biologi och bioteknik, Industriell bioteknik

Cecilia Geijer

Chalmers, Biologi och bioteknik, Industriell bioteknik

Lisbeth Olsson

Chalmers, Biologi och bioteknik, Industriell bioteknik

37th Symposium on Biotechnology for Fuels and Chemicals

Ämneskategorier

Evolutionsbiologi

Bioenergi

Mikrobiologi

Drivkrafter

Hållbar utveckling

Styrkeområden

Energi

Livsvetenskaper och teknik