Biofuels Production projects

Improvement of Xylose Fermentation by Recombinant Saccharomyces Cerevisiae Through Systematic and Combinatorial Approaches - Completed

The research in this project aimed to improve efficiency (yield) and rate (productivity) of xylose fermentation by recombinant S. cerevisiae. Previous studies suggested that simultaneous perturbation of multiple genes might be required in order to facilitate high yield/productivity xylose fermentation by recombinant S. cerevisiae. However, such a set of gene targets enhancing xylose fermentation has not been known. This research contributed to the development of ethanol fermentation processes that will help make biofuel production economically viable.

project Highlights

2010 Highlights

Researchers aimed to optimize expression levels of xylose metabolic enzymes to increase ethanol yield and productivity by engineered yeast.  In 2010, Jin’s group identified optimum expression levels of xylose reductase, xylitol dehydrogenase, and xylulokinase and implemented them into both laboratory and industrial yeast strains.  The resulting strains were able to produce ethanol with high yields and productivities from xylose or a sugar mixture of glucose and xylose.  In addition, they developed an engineered yeast strain capable of co-fermenting xylose and cellobiose, a critical step towards enabling economic biofuel production.

2009 Highlights

Researchers isolated fast xylose-fermenting transformants, two of which produced significantly more ethanol and less xylitol. The two transformants contained the same plasmid, suggesting that the insert in the plasmid elicited improved xylose transformation. They also observed similar or even better improvements in xylose fermenting capability after integrating an overexpression cassette of the identified target. Jin’s group also cloned and expressed in yeast a new bacterial xylose isomerase (XI) gene from an anaerobic bacterium. Recombinant S. cerevisiae strains expressing that isomerase gene grew and fermented xylose as a sole carbon source without any adaptation.

 

Publications

Published in 2011

Xylitol Does Not Inhibit Fermentation by Engineered Saccharomyces cerevisiae Expressing xylA as Severely As It Inhibits Xylose Isomerase Reaction In Vitro, Suk-Jin Ha, Soo Rin Kim, Jin-Ho Choi, Myeong Soo Park, Yong-Su Jin, Applied Microbiology and Biotechnology, doi: 10.1007/s00253-011-3345-9, June 8, 2011.

 


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