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Global transcriptional changes of Clostridium acetobutylicum cultures with increased butanol:acetone ratios

Paper ID Volume ID Publish Year Pages File Format Full-Text
33359 44973 2012 9 PDF Available
Title
Global transcriptional changes of Clostridium acetobutylicum cultures with increased butanol:acetone ratios
Abstract

Artificial electron carriers have been widely used to shift the solvent ratio toward butanol in acetone–butanol–ethanol (ABE) fermentation of solventogenic clostridia according to decreased hydrogen production. In this study, first insights on the molecular level were gained to explore the effect of methyl viologen addition to cultures of Clostridium acetobutylicum. Employing batch fermentation in mineral salts medium, the butanol:acetone ratio was successively increased from 2.3 to 12.4 on a 100-ml scale in serum bottles and from 1.4 to 16.5 on a 1300-ml scale in bioreactors, respectively. The latter cultures were used for DNA microarray analyses to provide new information on the transcriptional changes referring to methyl viologen exposure and thus, exhibit gene expression patterns according to the manipulation of the cellular redox balance. Methyl viologen-exposed cultures revealed lower expression levels of the sol operon (CAP0162-0164) and the adjacent adc gene (CAP0165) responsible for solvent formation as well as iron and sulfate transporters and the CAC0105-encoded ferredoxin. On the contrary, genes for riboflavin biosynthesis, for the butyrate/butanol metabolic pathway and genes coding for sugar transport systems were induced. Interestingly, the adhE2-encoded bifunctional NADH-dependent aldhehyde/alcohol-dehydrogenase (CAP0035) was upregulated up to more than 100-fold expression levels as compared to the control culture without methyl viologen addition. The data presented here indicate a transcriptional regulation for decreased acetone biosynthesis and the redox-dependent substitution of adhE1 (CAP0162) by adhE2.

► Transcriptome profiling of methyl viologen-exposed batch cultures was conducted. ► Solventogenic pathways are regulated on the transcriptional level. ► Genes of the acetone biosynthesis were clearly downregulated. ► The aldehyde/alcohol dehydrogenase gene adhE1 (CAP0162) was significantly repressed. ► Its paralog adhE2 (CAP0035) was highly induced to substitute AdhE1.

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Global transcriptional changes of Clostridium acetobutylicum cultures with increased butanol:acetone ratios
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Publisher
Database: Elsevier - ScienceDirect
Journal: New Biotechnology - Volume 29, Issue 4, 15 May 2012, Pages 485–493
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us