This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
Synonyms: (R,S)-butylene glycol fermentation, (R,S)-butanediol fermentation, (R,S)-butanediol biosynthesis
|Superclasses:||Generation of Precursor Metabolites and Energy → Fermentation → Butanediol Biosynthesis|
Expected Taxonomic Range: Bacteria
Many bacterial species can ferment pyruvate to 2,3-butanediol via several intermediate compounds, including (S)-2-acetolactate, diacetyl and acetoin. Not all species carry the process all the way from pyruvate to 2,3-butanediol - some may stop earlier, accumulating some of the intermediates.
There are two isomeric forms of acetoin - (R)-acetoin and (S)-acetoin, and three isomeric forms of 2,3-butanediol (BD ) - (R,R)-2,3-butanediol, (S,S)-2,3-butanediol and (R,S)-2,3-butanediol. Different organisms produce different forms, or different combinations of the different forms. This pathway describes the production of (R,S)-2,3-butanediol from (R)-acetoin.
The conversion of acetoin to 2,3-butanediol, which is reversible, is performed by the enzyme acetoin reductase (AR), also known as 2,3-butanediol dehydrogenase (BDH). 4 types of AR activities have been identified, differing in the substrate and product stereo-specificity. One of these activities is the production (R,S)-2,3-butanediol from (R)-acetoin [Ui84]. Enzymes that catalyze this activity have been characterized from several organisms including Klebsiella pneumoniae [Ui97] and Geobacillus stearothermophilus [Giovannini96].
The metabolic function of 2,3-butanediol is not yet known, although it may play a role in preventing intracellular acidification by changing the metabolism from acid production to the formation of a neutral compound [Booth83]. In addition, the pathway might participate in regulation of the NADH/NAD+ ratio in the bacteria [Blomqvist93].
Superpathways: superpathway of 2,3-butanediol biosynthesis
Blomqvist93: Blomqvist K, Nikkola M, Lehtovaara P, Suihko ML, Airaksinen U, Straby KB, Knowles JK, Penttila ME (1993). "Characterization of the genes of the 2,3-butanediol operons from Klebsiella terrigena and Enterobacter aerogenes." J Bacteriol 175(5);1392-404. PMID: 8444801
Oppermann94: Oppermann FB, Steinbuchel A (1994). "Identification and molecular characterization of the aco genes encoding the Pelobacter carbinolicus acetoin dehydrogenase enzyme system." J Bacteriol 176(2);469-85. PMID: 8110297
Ui97: Ui, S., Okajima, Y., Mimura, A., Kanai, H., Kobayashi, T., Kudo, T. (1997). "Sequence analysis of the gene for and characterization of D-acetoin forming meso-2,3-butanediol dehydrogenase of Klebsiella pneumoniae expressed in Escherichia coli." J. Ferment. Bioeng. 83: 32-37.
Wardwell01: Wardwell SA, Yang YT, Chang HY, San KY, Rudolph FB, Bennett GN (2001). "Expression of the Klebsiella pneumoniae CG21 acetoin reductase gene in Clostridium acetobutylicum ATCC 824." J Ind Microbiol Biotechnol 27(4);220-7. PMID: 11687934
Zhang13: Zhang L, Xu Q, Zhan S, Li Y, Lin H, Sun S, Sha L, Hu K, Guan X, Shen Y (2013). "A new NAD(H)-dependent meso-2,3-butanediol dehydrogenase from an industrially potential strain Serratia marcescens H30." Appl Microbiol Biotechnol. PMID: 23666479
Otagiri01: Otagiri M, Kurisu G, Ui S, Takusagawa Y, Ohkuma M, Kudo T, Kusunoki M (2001). "Crystal structure of meso-2,3-butanediol dehydrogenase in a complex with NAD+ and inhibitor mercaptoethanol at 1.7 A resolution for understanding of chiral substrate recognition mechanisms." J Biochem 129(2);205-8. PMID: 11173520
Ui04: Ui S, Takusagawa Y, Sato T, Ohtsuki T, Mimura A, Ohkuma M, Kudo T (2004). "Production of L-2,3-butanediol by a new pathway constructed in Escherichia coli." Lett Appl Microbiol 39(6);533-7. PMID: 15548307
Ui99: Ui S, Mimura A, Ohkuma M, Kudo T (1999). "Formation of a chiral acetoinic compound from diacetyl by Escherichia coli expressing meso-2,3-butanediol dehydrogenase." Lett Appl Microbiol 28(6);457-60. PMID: 10389264
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