Metabolic flexibility of Clostridium acetobutylicum in response to methyl viologen addition

Peguin, S.; Goma, G.; Delorme, P.; Soucaille, Philippe

doi:10.1007/bf00173928

Cited by 69 publications

(37 citation statements)

References 30 publications

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“…Closed circles, C. acetobutylicum ATCC824; open circles, C. acetobutylicum rex::int(95); dark grey area, H 2 formation; light grey area, CO 2 formation; solid line, total gas volume hydrogenase activity, e.g. by the application of artificial electron carriers or sparging the culture with carbon monoxide (Kim et al 1984;Datta and Zeikus 1985;Peguin et al 1994;Hüsemann and Papoutsakis 1989). According to an increased NAD(P)H availability, more butanol and ethanol and less acetone were produced, clearly improving the alcohol-to-acetone ratio.…”

Section: Discussionmentioning

confidence: 98%

“…In addition, several external approaches to influence the metabolic redox status were performed in order to artificially shift the metabolism away from hydrogen production towards alcohol formation. These included the application of carbon monoxide gassing, addition of artificial electron acceptors such as methyl viologen or neutral red, increased H 2 pressure, iron limitation or change of exogenous redox potential as well as the utilisation of reduced substrates like glycerol (Girbal et al 1995;Hüsemann and Papoutsakis 1989;Doremus et al 1985;Kim et al 1984;Peguin et al 1994;Wang et al 2011;Hönicke et al 2012). Although some interesting results were obtained from these studies, the molecular regulatory circuits remain to be elucidated.…”

Section: Introductionmentioning

confidence: 92%

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The redox-sensing protein Rex, a transcriptional regulator of solventogenesis in Clostridium acetobutylicum

Wietzke

Bahl

2012

Appl Microbiol Biotechnol

101

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Solventogenic clostridia are characterised by their biphasic fermentative metabolism, and the main final product n-butanol is of particular industrial interest because it can be used as a superior biofuel. During exponential growth, Clostridium acetobutylicum synthesises acetic and butyric acids which are accompanied by the formation of molecular hydrogen and carbon dioxide. During the stationary phase, the solvents acetone, butanol and ethanol are produced. However, the molecular mechanisms of this metabolic switch are largely unknown so far. In this study, in silico, in vitro and in vivo analyses were performed to elucidate the function of the CAC2713-encoded redox-sensing transcriptional repressor Rex and its role in the solventogenic shift of C. acetobutylicum ATCC 824. Electrophoretic mobility shift assays showed that Rex controls the expression of butanol biosynthetic genes as a response to the cellular NADH/NAD(+) ratio. Interestingly, the Rex-negative mutant C. acetobutylicum rex::int(95) produced high amounts of ethanol and butanol, while hydrogen and acetone production were significantly reduced. Both ethanol and butanol (but not acetone) formation started clearly earlier than in the wild type. In addition, the rex mutant showed a de-repression of the bifunctional aldehyde/alcohol dehydrogenase 2 encoded by the adhE2 gene (CAP0035) as demonstrated by increased adhE2 expression as well as high NADH-dependent alcohol dehydrogenase activities. The results presented here clearly indicated that Rex is involved in the redox-dependent solventogenic shift of C. acetobutylicum.

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Section: Discussionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 92%

The redox-sensing protein Rex, a transcriptional regulator of solventogenesis in Clostridium acetobutylicum

Wietzke

Bahl

2012

Appl Microbiol Biotechnol

101

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“…Previous studies have documented the shift in metabolism to greater butanol and lactate production in Clostridium sp. due to exogenous electron mediators (Peguin et al, 1994;Peguin and Soucaille, 1995;Reimann et al, 1996;Sund et al, 2007;Tashiro et al, 2007;Hönicke et al, 2012;Yarlagadda et al, 2012). In those studies, it was proposed that methyl viologen can replace ferredoxin and thus be preferentially used to generate NADH by the ferredoxin:NAD(P) reductase at the expense of H 2 , requiring activation of the lactate dehydrogenase to consume NADH.…”

Section: Discussionmentioning

confidence: 99%

Impact of iron reduction on the metabolism of Clostridium acetobutylicum

List

Hosseini

Meibom

et al. 2019

Environmental Microbiology

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SummaryIron is essential for most living organisms. In addition, its biogeochemical cycling influences important processes in the geosphere (e.g., the mobilization or immobilization of trace elements and contaminants). The reduction of Fe(III) to Fe(II) can be catalysed microbially, particularly by metal‐respiring bacteria utilizing Fe(III) as a terminal electron acceptor. Furthermore, Gram‐positive fermentative iron reducers are known to reduce Fe(III) by using it as a sink for excess reducing equivalents, as a form of enhanced fermentation. Here, we use the Gram‐positive fermentative bacterium Clostridium acetobutylicum as a model system due to its ability to reduce heavy metals. We investigated the reduction of soluble and solid iron during fermentation. We found that exogenous (resazurin, resorufin, anthraquinone‐2,6‐disulfonate) as well as endogenous (riboflavin) electron mediators enhance solid iron reduction. In addition, iron reduction buffers the pH, and elicits a shift in the carbon and electron flow to less reduced products relative to fermentation. This study underscores the role fermentative bacteria can play in iron cycling and provides insights into the metabolic profile of coupled fermentation and iron reduction with laboratory experiments and metabolic network modelling.

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“…Previous efforts have been applied to enhance the butanol/acetone ratio by implementing oxidative-reductive-potential control [15], redistributing the carbon flux to butanol by the addition of precursor of cofactors [14], using mixed substrates [16], employing metabolic engineering methods [3,13,17] and inhibiting the hydrogenase enzyme by the addition of electron carriers such as methyl viologen and neutral red [18][19][20]. The production of butanol without acetone and acids using solvent-producing Clostridia is difficult by metabolic engineering due to the inability to control the electron flow, which may be affected by unknown pSOL1 genes [21].…”

Section: A N U S C R I P Tmentioning

confidence: 99%

Improvement of the butanol production selectivity and butanol to acetone ratio (B:A) by addition of electron carriers in the batch culture of a new local isolate of Clostridium acetobutylicum YM1

et al. 2015

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Metabolic flexibility of Clostridium acetobutylicum in response to methyl viologen addition

Cited by 69 publications

References 30 publications

The redox-sensing protein Rex, a transcriptional regulator of solventogenesis in Clostridium acetobutylicum

The redox-sensing protein Rex, a transcriptional regulator of solventogenesis in Clostridium acetobutylicum

Impact of iron reduction on the metabolism of Clostridium acetobutylicum

Improvement of the butanol production selectivity and butanol to acetone ratio (B:A) by addition of electron carriers in the batch culture of a new local isolate of Clostridium acetobutylicum YM1

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