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Thermoanaerobacter spp. control ethanol pathway via transcriptional regulation and versatility of key enzymes

Paper ID Volume ID Publish Year Pages File Format Full-Text
31680 44829 2010 9 PDF Available
Title
Thermoanaerobacter spp. control ethanol pathway via transcriptional regulation and versatility of key enzymes
Abstract

Ethanologenic Thermoanaerobacter species produce ethanol from lignocellulose derived substrates at temperatures above 70 °C. In the final steps of ethanol formation, two bifunctional acetaldehyde/alcohol dehydrogenases, AdhB and AdhE, and an alcohol dehydrogenase, AdhA, catalyze redox reactions between acetyl-CoA and ethanol via an acetaldehyde intermediate. DNA cloning and analysis revealed that the dehydrogenase genes and their transcriptional regulatory regions were highly conserved in these species. As determined by real-time PCR, the transcription of adhE was activated by ethanol, while adhB was transcribed without ethanol; however, all of their transcription was reduced at higher ethanol concentrations. Under imitating physiological conditions, AdhE played a crucial role in ethanol formation, and AdhB favored ethanol consumption when ethanol concentration was high e.g. 1%. Thus, the ethanol titer of fermentation is controlled via transcriptional regulation and the properties of specific enzymes in Thermoanaerobacter. These results provide evidence for an ethanol balance model and offer the possibility to raise the ethanol titer by metabolic engineering.

Keywords
Acetaldehyde dehydrogenase; Ethanol formation; Physiological function; Thermoanaerobacters; Transcriptional regulation
First Page Preview
Thermoanaerobacter spp. control ethanol pathway via transcriptional regulation and versatility of key enzymes
Publisher
Database: Elsevier - ScienceDirect
Journal: Metabolic Engineering - Volume 12, Issue 5, September 2010, Pages 420–428
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering