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Techniques for the Evolution of Robust Pentose-fermenting Yeast for Bioconversion of Lignocellulose to Ethanol
Published on: October 24, 2016
Engineering a native homoethanol pathway in Escherichia coli B for ethanol production
S Zhou1, A G Iverson, W S Grayburn
1Department of Biological Sciences, Northern Illinois University, DeKalb, IL 60115, USA. szhou@niu.edu
Abstract:
A native homoethanol pathway (pyruvate-to-acetyl-CoA-to-acetaldehyde-to-ethanol) was engineered in Escherichia coli B. The competing fermentation pathways were eliminated by chromosomal deletions of the genes encoding for fumarate reductase (frdABCD), lactate dehydrogenase (ldhA), acetate kinase (ackA), and pyruvate formate lyase (pflB). For redox balance and anaerobic cell growth, the pyruvate dehydrogenase complex (aceEF-lpd, a typical aerobically-expressed operon) was highly expressed anaerobically using a native anaerobic inducible promoter. The resulting strain SZ420 (DeltafrdBC DeltaldhA DeltaackA DeltafocA-pflB DeltapdhR::pflBp6-pflBrbs-aceEF-lpd) contains no foreign genes and/or promoters and efficiently ferments glucose and xylose into ethanol with a yield of 90% under anaerobic conditions.
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