Engineering a native homoethanol pathway in Escherichia coli B for ethanol production

• DOI: 10.1007/s10529-007-9544-x
• Publication Date: 2007-10-23T11:03:20Z
• Authors: S. Zhou; A. G. Iverson; W. S. Grayburn
• Keywords: 0303 health sciences; Xylose; Ethanol; Pyruvate Dehydrogenase Acetyl-Transferring Kinase; Protein Serine-Threonine Kinases; Protein Engineering; 3. Good health; 03 medical and health sciences; Genetic Enhancement; Glucose; Fermentation; Escherichia coli; Anaerobiosis; Signal Transduction

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.