Biofuels Production projects

Robustness to Environmental Heterogeneity – Engineering Strains Optimized for Large-Scale Fermentation - Completed

The team in this project worked to genetically engineer E. coli to efficiently and robustly utilize glucose, arabinose, and xylose for the production of diverse biofuels. They characterized multiple-sugar utilization at a single-cell resolution level. They also constructed a computational model of multiple sugar utilization.

project Highlights

2010 Highlights

Rao’s group characterized the regulation of C5 and C6 sugar utilization. Their key contribution was determining how E. coli regulates the selective utilization of C5 sugars. They also identified and characterized a number of sugar efflux transporters. They also engineered strains of E. coli to efficiently utilize both C5 and C6 sugars by reprogramming gene expression and sugar transport.

2009 Highlights

AraC, the transcriptional regulator for the arabinose metabolic genes, binds to the xylose promoters and represses the expression of the xylose metabolic genes in the presence of arabinose, preventing E. coli from simultaneously fermenting the two sugars. Rao’s group identified the AraC binding site within the xylose promoters, laying the foundation for future engineering work. E. coli also expresses a number of proteins that pump arabinose and xylose out of the cell. Little is known about these efflux transporters. Rao’s team successfully cloned each individual transporter on an overexpression vector and generated an in-frame chromosomal deletion. To date, they have characterized eight and found that six affect pentose utilization.

 

Publications

Published in 2010

Regulation of Arabinose and Xylose in Escherichia coli, Tasha Desai and Christopher Rao, Applied and Environmental Microbiology, 76(5): pp. 1524-1532, March 2010.

 


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