Genetic Changes To Optimize Carbon Partitioning between Ethanol and Biosynthesis in EthanologenicEscherichia coli

• DOI: 10.1128/aem.68.12.6263-6272.2002
• Publication Date: 2002-11-26T00:04:48Z
• Authors: S. A. Underwood; S. Zhou; T. B. Causey; L. P. Yomano; K. T. Shanmugam; L. O. Ingram
• Keywords: Acetate kinase; Metabolic Engineering; Pyruvic acid

ABSTRACT The production of ethanol from xylose by ethanologenic Escherichia coli strain KO11 was improved adding various medium supplements (acetate, pyruvate, and acetaldehyde) that prolonged the growth phase increasing cell yield volumetric productivity (approximately twofold). Although added pyruvate acetaldehyde were rapidly metabolized, benefit these additives continued throughout fermentation. Both increased levels extracellular acetate through different mechanisms. Since can be reversibly converted to acetyl coenzyme A (acetyl-CoA) kinase phosphotransacetylase, increase in caused each three is proposed result an pool acetyl-CoA. similar obtained inactivation ( ackA ), reducing (and ATP) sparing acetyl-CoA for biosynthetic needs. Inactivation native E. alcohol-aldehyde dehydrogenase adhE which uses as electron acceptor, had no beneficial effect on growth, consistent with a minor role this enzyme during production. Growth appears limited partitioning carbon skeletons into biosynthesis rather than level ATP. Changes consumption provide useful approach modulate partitioning. Together, results demonstrate fermentation redirecting small amounts away products biosynthesis. Though negligible respect yield, changes reduced time required complete 9.1% 1% corn steep liquor over 96 h less 72 h.