Targeted mutagenesis of the Clostridium acetobutylicum acetone–butanol–ethanol fermentation pathway

Cooksley, Clare; Zhang, Ying; Wang, Hengzheng; Redl, Stephanie Maria Anna; Winzer, Klaus; Minton, Nigel P.

doi:10.1016/j.ymben.2012.09.001

Cited by 133 publications

(94 citation statements)

References 52 publications

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“…This indicates that during continuous cultivation (and in contrast to batch cultivation (Cooksley et al 2012;Lehmann et al 2012a)) butanol formation is not greatly inhibited by disruption of the acetone formation as proposed by . Furthermore, the contribution of butanol to the pool of fermentation products seems to be less affected by the mutation.…”

Section: Comparison Of Simulation and Experimental Datamentioning

confidence: 62%

“…2) had revealed that the CoA-transferase mutant Cac-ctfA398s::CT is able to shift its metabolism from acid-production to solvent-production, see also (Cooksley et al 2012;Lehmann et al 2012a) for similar results using batch cultures. Importantly and in accordance with our expectations, this mutant is unable to form acetone during both phases.…”

Section: Comparison Of Simulation and Experimental Datamentioning

confidence: 86%

“…The CoA-transferase defective strain C. acetobutylicum Cac-ctfA398s::CT was recently constructed and analysed as described in Cooksley et al (2012). For the purpose of systematic comparison between the mutant and the wild type, the experiments were conducted using the same experimental setup and standard operating procedure (SOP) as for the type strain C. acetobutylicum ATCC 824 (COSMIC strain, Rostock lab collection) (Janssen et al 2010).…”

Section: Methodsmentioning

confidence: 99%

“…(4c) and (4h). However, whereas recent batch and continuous culture experiments have verified the crucial role of AdhE1 in the transition from acid-to solvent formation using the mutant C. acetobutylicum Cac-adhE1468s::CT, the mutant C. acetobutylicum Cac-adhE2696s::CT continues to form ethanol and, thus, challenges our current view on clostridial ethanol production (Cooksley et al 2012). Acidogenic-and solventogenic-specific kinetic parameters were introduced for those enzymes exhibiting significant changes of their specific activities.…”

Section: Adhe1 Acmentioning

confidence: 99%

“…Furthermore, secondary growth and stress responses of cells growing in a batch might obscure physiological differences (Hoskisson and Hobbs 2005). For our experiments we used the wild type strain ATCC 824 (COSMIC strain) and the group II intron retargeted mutant strain Cac-ctfA398s::CT originating from the COSMIC strain (Cooksley et al 2012).…”

Section: Introductionmentioning

confidence: 99%

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Coenzyme A-transferase-independent butyrate re-assimilation in Clostridium acetobutylicum—evidence from a mathematical model

Millat

Voigt

Janssen

et al. 2014

Appl Microbiol Biotechnol

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(2014) Coenzyme A-transferaseindependent butyrate re-assimilation in Clostridium acetobutylicum -evidence from a mathematical model. Applied Microbiology and Biotechnology, 98 (21 A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription.For more information, please contact eprints@nottingham.ac.uk Coenzyme A-transferase-independent butyrate re-assimilation in Clostridium acetobutylicum -Evidence from a mathematical model Abstract: The hetero-dimeric CoA-transferase CtfA/B is believed to be crucial for the metabolic transition from acidogenesis to solventogenesis in Clostridium acetobutylicum as part of the industrial-relevant acetone-butanol-ethanol (ABE) fermentation. Here, the enzyme is assumed to mediate re-assimilation of acetate and butyrate during a pH-induced metabolic shift and to faciliate the first step of acetone formation from acetoacetyl-CoA. However, recent investigations using phosphate-limited continuous cultures have questioned this common dogma.To adress the emerging experimental discrepancies, we investigated the mutant strain Cac-ctfA398s::CT using chemostat cultures. As a consequence of this mutation, the cells are unable to express functional ctfA and are thus lacking CoA-transferase activity. A mathematical model of the pH-induced metabolic shift, which was recently developed for the wild type, is used to analyse the observed behaviour of the mutant strain with a focus on re-assimilation activities for the two produced acids.Our theoretical analysis reveals that the ctfA mutant still re-assimilates butyrate, but not acetate. Based upon this finding, we conclude that C. acetobutylicum possesses a CoA-tranferase-independent butyrate uptake mechanism that is activated by decreasing pH levels. Furthermore, we observe that butanol formation is not inhibited under our experimental conditions, as suggested by previous batch culture experiments. In concordance with recent batch experiments, acetone formation is abolished in chemostat cultures using the ctfa mutant.

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Section: Comparison Of Simulation and Experimental Datamentioning

confidence: 62%

Section: Comparison Of Simulation and Experimental Datamentioning

confidence: 86%