If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
|Superclasses:||Generation of Precursor Metabolites and Energy → Fermentation → Pyruvate Fermentation|
Expected Taxonomic Range: Firmicutes
Please note: The enzymes depicted in this superpathway are not induced simultaneously, and the organisms can not produce all of the products shown here at the same time. This superpathway is for illustrative purposes only, as it shows the branching points between the different products. For more information about the pathways leading to fermentation of individual compounds, please look at the respective sub-pathways - pyruvate fermentation to ethanol III, pyruvate fermentation to acetate I, pyruvate fermentation to butanoate, pyruvate fermentation to butanol I and pyruvate fermentation to acetone.
Clostridium acetobutylicum is a Gram-positive anaerobe of commercial importance, capable of fermenting a variety of sugars to solvents and acids. During acidogenesis acetate and butanoate are produced, while solventogenesis yields ethanol, acetone, and n-butanol. The production of acetone and butanol by Clostridium acetobutylicum was a thriving industrial process, but lost its importance since the fermentation could no longer compete economically with the chemical synthesis of solvents from petroleum.
In continuous culture, Clostridium acetobutylicum can be maintained in three different stable metabolic states [Girbal95]: acidogenic - production of acetate and butanoate when grown at neutral pH on glucose (see superpathway of Clostridium acetobutylicum acidogenic fermentation), solventogenic - production of acetone, n-butanol and ethanol when grown at low pH on glucose (superpathway of Clostridium acetobutylicum solventogenic fermentation), and alcohologenic - formation of n-butanol and ethanol but not acetone when grown at neutral pH under conditions of high NAD(P)H availability. Despite numerous physiological studies, it is still unclear how the metabolic switch from acid to solvent production is regulated at the molecular level [Green98]. Once this metabolic transition has been initiated, most of the excreted acids are taken up and converted into solvents
The three key intermediates are acetyl-CoA, acetoacetyl-CoA, and butanoyl-CoA. Acetyl-CoA is a branching point for the production of acetate and ethanol. Acetoacetyl-CoA is the branching point for acetone production, and butanoyl-CoA is the branching point for butanoate and n-butanol production.
Subpathways: pyruvate fermentation to acetone , pyruvate fermentation to ethanol III , pyruvate fermentation to butanol I , superpathway of Clostridium acetobutylicum solventogenic fermentation , superpathway of Clostridium acetobutylicum acidogenic fermentation , acetate formation from acetyl-CoA I , pyruvate fermentation to acetate I , pyruvate fermentation to butanoate
Variants: pyruvate fermentation to acetate and alanine , pyruvate fermentation to acetate and lactate I , pyruvate fermentation to acetate and lactate II , pyruvate fermentation to acetate II , pyruvate fermentation to acetate III , pyruvate fermentation to acetate IV , pyruvate fermentation to acetate V , pyruvate fermentation to acetate VI , pyruvate fermentation to acetate VII , pyruvate fermentation to acetate VIII , pyruvate fermentation to butanol II , pyruvate fermentation to ethanol I , pyruvate fermentation to ethanol II , pyruvate fermentation to hexanol , pyruvate fermentation to isobutanol (engineered) , pyruvate fermentation to lactate , pyruvate fermentation to opines , pyruvate fermentation to propanoate I , pyruvate fermentation to propanoate II (acrylate pathway) , superpathway of fermentation (Chlamydomonas reinhardtii)
Aceti88: Aceti DJ, Ferry JG (1988). "Purification and characterization of acetate kinase from acetate-grown Methanosarcina thermophila. Evidence for regulation of synthesis." J Biol Chem 1988;263(30);15444-8. PMID: 2844814
Alber06: Alber BE, Spanheimer R, Ebenau-Jehle C, Fuchs G (2006). "Study of an alternate glyoxylate cycle for acetate assimilation by Rhodobacter sphaeroides." Mol Microbiol 61(2);297-309. PMID: 16856937
Asanuma05: Asanuma N, Ishiwata M, Yoshii T, Kikuchi M, Nishina Y, Hino T (2005). "Characterization and transcription of the genes involved in butyrate production in Butyrivibrio fibrisolvens type I and II strains." Curr Microbiol 51(2);91-4. PMID: 15991056
Atteia06: Atteia A, van Lis R, Gelius-Dietrich G, Adrait A, Garin J, Joyard J, Rolland N, Martin W (2006). "Pyruvate formate-lyase and a novel route of eukaryotic ATP synthesis in Chlamydomonas mitochondria." J Biol Chem 281(15);9909-18. PMID: 16452484
Autor70: Autor AP, Fridovich I (1970). "The interactions of acetoacetate decarboxylase with carbonyl compounds, hydrogen cyanide, and an organic mercurial." J Biol Chem 1970;245(20);5214-22. PMID: 5469163
Beh93: Beh M, Strauss G, Huber R, Stetter K-O, Fuchs G (1993). "Enzymes of the reductive citric acid cycle in the autotrophic eubacterium Aquifex pyrophilus and in the archaebacterium Thermoproteus neutrophilus." Arch Microbiol 160: 306-311.
Bergmeyer63: Bergmeyer, H.U., Holz, G., Klotzsch, H., Lang, G. (1963). "[Phosphotransacetylase from Clostridium kluyveri. Culture of the bacterium, isolation, crystallization and properties of the enzyme.]." Biochem Z 338;114-21. PMID: 14087284
Bermejo98: Bermejo LL, Welker NE, Papoutsakis ET (1998). "Expression of Clostridium acetobutylicum ATCC 824 genes in Escherichia coli for acetone production and acetate detoxification." Appl Environ Microbiol 1998;64(3);1079-85. PMID: 9501448
Bindschedler05: Bindschedler LV, Wheatley E, Gay E, Cole J, Cottage A, Bolwell GP (2005). "Characterisation and expression of the pathway from UDP-glucose to UDP-xylose in differentiating tobacco tissue." Plant Mol Biol 57(2);285-301. PMID: 15821883
Blamey93: Blamey JM, Adams MW (1993). "Purification and characterization of pyruvate ferredoxin oxidoreductase from the hyperthermophilic archaeon Pyrococcus furiosus." Biochim Biophys Acta 1161(1);19-27. PMID: 8380721
Blamey94: Blamey JM, Adams MW (1994). "Characterization of an ancestral type of pyruvate ferredoxin oxidoreductase from the hyperthermophilic bacterium, Thermotoga maritima." Biochemistry 1994;33(4);1000-7. PMID: 8305426
Blaschkowski82: Blaschkowski HP, Neuer G, Ludwig-Festl M, Knappe J (1982). "Routes of flavodoxin and ferredoxin reduction in Escherichia coli. CoA-acylating pyruvate: flavodoxin and NADPH: flavodoxin oxidoreductases participating in the activation of pyruvate formate-lyase." Eur J Biochem 123(3);563-9. PMID: 7042345
Bock99: Bock AK, Glasemacher J, Schmidt R, Schonheit P (1999). "Purification and characterization of two extremely thermostable enzymes, phosphate acetyltransferase and acetate kinase, from the hyperthermophilic eubacterium Thermotoga maritima." J Bacteriol 1999;181(6);1861-7. PMID: 10074080
Bologna10: Bologna FP, Campos-Bermudez VA, Saavedra DD, Andreo CS, Drincovich MF (2010). "Characterization of Escherichia coli EutD: a phosphotransacetylase of the ethanolamine operon." J Microbiol 48(5);629-36. PMID: 21046341
Boyer72: Boyer PD, editor (1972). "Chapter 8- Acetoacetate Decarboxylase." The Enzymes, Third Edition, Volume Six, Carboxylation and decarboxylation (nonoxidative) isomerization, Academic Press New York.
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