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Metabolic engineering of Geobacillus thermoglucosidasius for high yield ethanol production

Paper ID Volume ID Publish Year Pages File Format Full-Text
31800 44839 2009 11 PDF Available
Title
Metabolic engineering of Geobacillus thermoglucosidasius for high yield ethanol production
Abstract

We describe the metabolic engineering of two strains of Geobacillus thermoglucosidasius to divert their fermentative carbon flux from a mixed acid pathway, to one in which ethanol becomes the major product. This involved elimination of the lactate dehydrogenase and pyruvate formate lyase pathways by disruption of the ldh and pflB genes, respectively, together with upregulation of expression of pyruvate dehydrogenase. Unlike the situation in Escherichia coli, pyruvate dehydrogenase is active under anaerobic conditions in thermophilic bacilli, but expressed sub-optimally for a role as the primary fermentation pathway. Mutants were initially characterised in batch culture using glucose as carbon substrate and strains with all three modifications shown to form ethanol efficiently and rapidly at temperatures in excess of 60 °C in yields in excess of 90% of theoretical. The strain containing the 3 modifications, TM242, was also shown to efficiently ferment cellobiose and a mixed hexose and pentose feed.

Keywords
Geobacillus; Metabolic engineering; Bioethanol; Thermophile
First Page Preview
Metabolic engineering of Geobacillus thermoglucosidasius for high yield ethanol production
Publisher
Database: Elsevier - ScienceDirect
Journal: Metabolic Engineering - Volume 11, Issue 6, November 2009, Pages 398–408
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering