Balancing redox cofactor generation and ATP synthesis: key microaerobic responses in thermophilic fermentations

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dc.contributor.authorLoftie-Eaton, Wesley
dc.contributor.authorTaylor, Mark
dc.contributor.authorHorne, Kerry
dc.contributor.authorTuffin, Marla I.
dc.contributor.authorBurton, Stephanie G.
dc.contributor.authorCowan, Donald A.
dc.date.accessioned2018-02-15T13:16:15Z
dc.date.available2018-02-15T13:16:15Z
dc.date.issued2013
dc.description.abstractGeobacillus thermoglucosidasius is a Grampositive, thermophilic bacterium capable of ethanologenic fermentation of both C5 and C6 sugars and may have possible use for commercial bioethanol production [Tang et al., 2009; Taylor et al. (2009) Trends Biotechnol 27(7): 398–405]. Little is known about the physiological changes that accompany a switch from aerobic (high redox) to microaerobic/fermentative (low redox) conditions in thermophilic organisms. The changes in the central metabolic pathways in response to a switch in redox potential were analyzed using quantitative real-time PCR and proteomics. During low redox (fermentative) states, results indicated that glycolysis was uniformly up-regulated, the Krebs (tricarboxylic acid or TCA) cycle non-uniformly downregulated and that there was little to no change in the pentose phosphate pathway. Acetate accumulation was accounted for by strong down-regulation of the acetate CoA ligase gene (acs) in addition to up-regulation of the pta and ackA genes (involved in acetate production), thus conserving ATP while reducing flux through the TCA cycle. Substitution of an NADH dehydrogenase (down-regulated) by an up-regulated NADH:FAD oxidoreductase and upregulation of an ATP synthase subunit, alongside the observed shifts in the TCA cycle, suggested that an oxygenscavenging electron transport chain likely remained active during low redox conditions. Together with the observed up-regulation of a glyoxalase and down-regulation of superoxide dismutase, thought to provide protection against the accumulation of toxic phosphorylated glycolytic intermediates and reactive oxygen species, respectively, the changes observed in G. thermoglucosidasius NCIMB 11955 under conditions of aerobic-to-microaerobic switching were consistent with responses to low pO2 stress.en_US
dc.description.accreditationWeb of Science
dc.identifier.citationLoftie-Eaton, W. et al. (2013). Balancing redox cofactor generation and ATP synthesis : key microaerobic responses in thermophilic fermentations. Biotechnology and Bioengineering, 110(4): 1057 – 1065en_US
dc.identifier.issn0006-3592
dc.identifier.urihttp://dx.doi.org/10.1002/bit.24774
dc.identifier.urihttp://hdl.handle.net/10566/3496
dc.language.isoenen_US
dc.privacy.showsubmitterFALSE
dc.publisherWileyen_US
dc.rightsThis is the author-version of the article published online at: http://dx.doi.org/10.1002/bit.24774
dc.status.ispeerreviewedTRUE
dc.subjectGeobacillus thermoglucosidasiusen_US
dc.subjectGlycolysisen_US
dc.subjectGram-positiveen_US
dc.subjectProteomicsen_US
dc.subjectReal-time PCRen_US
dc.subjectTricarboxylic acid cycleen_US
dc.subjectGlyoxal shunten_US
dc.titleBalancing redox cofactor generation and ATP synthesis: key microaerobic responses in thermophilic fermentationsen_US
dc.typeArticleen_US

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