CoChat
Sign Up
Cited by 221Microbial Metabolic Engineering and BioproductionAnaerobic Digestion and Biogas ProductionBiofuel production and bioconversion

The DOI matches its Crossref record; 88 of the 88 references it cites were found in a registry or an index.

Energy Conservation Associated with Ethanol Formation from H 2 and CO 2 in Clostridium autoethanogenum Involving Electron Bifurcation

Open access
Mock, Johanna, Zheng, Yanning, Mueller, Alexander P., Ly, San, Tran, Loan, Segovia, Simon, Nagaraju, Shilpa, Köpke, Michael, Dürre, Peter, Thauer, Rudolf K.·2015·Journal of Bacteriology
DOI 10.1128/jb.00399-15PMC PMC4542177
Open this paper in CoChat — free account

Abstract

UNLABELLED: Most acetogens can reduce CO2 with H2 to acetic acid via the Wood-Ljungdahl pathway, in which the ATP required for formate activation is regenerated in the acetate kinase reaction. However, a few acetogens, such as Clostridium autoethanogenum, Clostridium ljungdahlii, and Clostridium ragsdalei, also form large amounts of ethanol from CO2 and H2. How these anaerobes with a growth pH optimum near 5 conserve energy has remained elusive. We investigated this question by determining the specific activities and cofactor specificities of all relevant oxidoreductases in cell extracts of H2/CO2-grown C. autoethanogenum. The activity studies were backed up by transcriptional and mutational analyses. Most notably, despite the presence of six hydrogenase systems of various types encoded in the genome, the cells appear to contain only one active hydrogenase. The active [FeFe]-hydrogenase is electron bifurcating, with ferredoxin and NADP as the two electron acceptors. Consistently, most of the other active oxidoreductases rely on either reduced ferredoxin and/or NADPH as the electron donor. An exception is ethanol dehydrogenase, which was found to be NAD specific. Methylenetetrahydrofolate reductase activity could only be demonstrated with artificial electron donors. Key to the understanding of this energy metabolism is the presence of membrane-associated reduced ferredoxin:NAD(+) oxidoreductase (Rnf), of electron-bifurcating and ferredoxin-dependent transhydrogenase (Nfn), and of acetaldehyde:ferredoxin oxidoreductase, which is present with very high specific activities in H2/CO2-grown cells. Based on these findings and on thermodynamic considerations, we propose metabolic schemes that allow, depending on the H2 partial pressure, the chemiosmotic synthesis of 0.14 to 1.5 mol ATP per mol ethanol synthesized from CO2 and H2. IMPORTANCE: Ethanol formation from syngas (H2, CO, and CO2) and from H2 and CO2 that is catalyzed by bacteria is presently a much-discussed process for sustainable production of biofuels. Although the process is already in use, its biochemistry is only incompletely understood. The most pertinent question is how the bacteria conserve energy for growth during ethanol formation from H2 and CO2, considering that acetyl coenzyme A (acetyl-CoA), is an intermediate. Can reduction of the activated acetic acid to ethanol with H2 be coupled with the phosphorylation of ADP? Evidence is presented that this is indeed possible, via both substrate-level phosphorylation and electron transport phosphorylation. In the case of substrate-level phosphorylation, acetyl-CoA reduction to ethanol proceeds via free acetic acid involving acetaldehyde:ferredoxin oxidoreductase (carboxylate reductase).

Overview

Integrity signals

Registry

Crossref · 10.1128/jb.00399-15

Cites

88 of 88 references verified0 citation errors · 0 not checkable

Statistics

Recomputing p-values needs the paper’s full text.

Verification

Claims the paper makes

We couldn’t retrieve this paper’s full text, so its claims and self-check weren’t run. The registry and citation checks still apply.

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

Citations

Cites

Research works printed but not linked: 2

  1. Thauer RK, Morris JG. 1984. Metabolism of chemotrophic anaerobes: old views and new aspects, p 123–168. In Kelly PD, Carr NG (ed), The microbe 1984, pt II. Cambridge University Press, Cambridge, United Kingdom.
  2. Kim YK, Hong S, Kyoo KK. 2011. Effect of pH on growth and ethanol production of Clostridium ljundahlii. Appl Chem Eng 22:562–565.

Cited by

Sorted by citations

See all 221

Related

See all

Metadata

Authors
Mock, J., Zheng, Y., Mueller, A. P., Ly, S., Tran, L., Segovia, S., Nagaraju, S., Köpke, M., Dürre, P., & Thauer, R. K.
Affiliations
  • Max Planck Institute for Terrestrial Microbiology (DE)
  • LanzaTech Inc., Skokie, Illinois, USA
  • Universität Ulm (DE)
ORCID
Venue
Journal of Bacteriology
Publisher
American Society for Microbiology
Published
2015-09-15
Volume
197
Issue
18
Pages
2965-2980
ISSN
  • 0021-9193 (ISSN-L)
  • 1098-5530
DOI
10.1128/jb.00399-15
PMC
PMC4542177
OpenAlex
W1841900872
Cited by
220
References
88
Citations by year
2026: 13 · 2025: 17 · 2024: 18 · 2023: 25 · 2022: 26 · 2021: 18 · 2020: 27 · 2019: 21 · 2018: 20 · 2017: 13 · 2016: 16 · 2015: 6
FWCI
7.96
Type
journal article
Language
en
Open access
Licence
journals.asm.org/non-commercial-tdm-license (tdm)
Locations
  • Journal of Bacteriology (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
  • Max Planck Institute for Plasma Physics (submittedVersion)
  • MPG.PuRe (Max Planck Society) (submittedVersion)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Microbial Metabolic Engineering and Bioproduction
  • Physical Sciences › Energy › Renewable Energy, Sustainability and the Environment › Anaerobic Digestion and Biogas Production
  • Physical Sciences › Engineering › Biomedical Engineering › Biofuel production and bioconversion
Keywords
Clostridium autoethanogenum, ethanol production, electron bifurcation, energy conservation, acetogenic bacteria, hydrogenase, [FeFe]-hydrogenase, methylenetetrahydrofolate reductase, ethanol dehydrogenase, Wood-Ljungdahl pathway, ATP production, syngas conversion, biofuel production
MeSH terms
Acetyl Coenzyme A, Adenosine Diphosphate, Ethanol, Bacterial Proteins, Carbon Dioxide, Clostridium, Electron Transport, Energy Metabolism, Hydrogen, Membrane Proteins, Oxidoreductases, Phosphoproteins, Gene Expression Regulation, Bacterial, Gene Expression Regulation, Enzymologic, Acetic Acid

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review