Relationship between pyruvate utilization and acetoin production by<i>Lactobacillus plantarum:</i>influence of carbon source, pyruvate concentration, and metabolic inhibitors

Tsau, Jya-Li; Montvllle, Thomas J.

doi:10.1080/08905439009549784

Cited by 6 publications

(7 citation statements)

References 23 publications

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“…lactis bv. diacetylactis (22), Leuconostoc lactis (9), Lactobacillus lactis (30), and Lactobacillus plantarum (56), generate acetoin from exogenous citrate, which is taken up by a plasmid-encoded citrate permease. In L. lactis, the degradation of citrate presumably leads to an excess of pyruvate, which is converted subsequently into AL.…”

Section: Discussionmentioning

confidence: 99%

Dual role of alpha-acetolactate decarboxylase in Lactococcus lactis subsp. lactis

et al. 1997

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The ␣-acetolactate decarboxylase gene aldB is clustered with the genes for the branched-chain amino acids (BCAA) in Lactococcus lactis subsp. lactis. It can be transcribed with BCAA genes under isoleucine regulation or independently of BCAA synthesis under the control of its own promoter. The product of aldB is responsible for leucine sensibility under valine starvation. In the presence of more than 10 M leucine, the ␣-acetolactate produced by the biosynthetic acetohydroxy acid synthase IlvBN is transformed to acetoin by AldB and, consequently, is not available for valine synthesis. AldB is also involved in acetoin formation in the 2,3-butanediol pathway, initiated by the catabolic acetolactate synthase, AlsS. The differences in the genetic organization, the expression, and the kinetics parameters of these enzymes between L. lactis and Klebsiella terrigena, Bacillus subtilis, or Leuconostoc oenos suggest that this pathway plays a different role in the metabolism in these bacteria. Thus, the ␣-acetolactate decarboxylase from L. lactis plays a dual role in the cell: (i) as key regulator of valine and leucine biosynthesis, by controlling the acetolactate flux by a shift to catabolism; and (ii) as an enzyme catalyzing the second step of the 2,3-butanediol pathway.Synthesis of the three branched-chain amino acids (BCAA), leucine, isoleucine, and valine, has been studied in detail in organisms as diverse as bacteria, fungi, and plants (for reviews, see references 8, 32, 57, and 58). A particular feature of this synthesis is that it is carried out, in part, by the same enzymes for the three amino acids (Fig. 1). However, the relative amounts of the three amino acids in cell proteins are not the same, since leucine, valine, and isoleucine represent 39, 36, and 25%, respectively, of the total BCAA in Escherichia coli (40). Regulation of the BCAA synthesis is therefore necessarily complex. A global regulation model has been established only for E. coli (58). Two levels of regulation, concerning gene transcription and enzyme inhibition, have previously been described.E. coli genes which encode BCAA synthesis enzymes form three clusters and are organized in five transcription units (2). Initiation of transcription of all the genes except ilvC is regulated by nonspecific, pleiotropic regulators responding to amino acid starvation and different changes in the medium (58). In addition to this control, a mechanism of transcriptional attenuation dependent on the synthesis of a leader peptide as described first for the tryptophan operon (33) negatively regulates ilvBN, ilvGMEDA, and leuABCD. These mechanisms allow the expression of the enzymes necessary for BCAA synthesis when needed.Activity of several BCAA-synthesizing enzymes is regulated by retroinhibition (Fig. 1). This control is simple in the case of leucine and isoleucine, since each amino acid inhibits an enzyme specific for an early step of its synthesis (LeuA and IlvA, respectively [53,57]). In contrast, the first enzyme involved in valine synthesis is also required fo...

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Section: Discussionmentioning

confidence: 99%

Dual role of alpha-acetolactate decarboxylase in Lactococcus lactis subsp. lactis

et al. 1997

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“…In homofermentative lactic acid bacteria, most of the pyruvate must be converted to lactate to regenerate NAD. Thus, little or no diacetyl and acetoin are produced unless an additional source of pyruvate, such as citrate, is present (4,9,15,27). Therefore, Gunsalus (7) proposed that a high concentration of intracellular pyruvate is required for diacetyl and acetoin synthesis.…”

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confidence: 99%

“…Exogenous pyruvate enhances acetoin production in Lactobacillus plantarum (19,21,22,27). When the organism is grown aerobically, acetoin production increases even in the absence of exogenous pyruvate (29).…”

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confidence: 99%

Conversion of Pyruvate to Acetoin Helps To Maintain pH Homeostasis in Lactobacillus plantarum

Tsau

Guffanti

Montville

1992

Appl Environ Microbiol

112

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Pyruvate is the substrate for diacetyl and acetoin synthesis by lactobacilli. Exogenous pyruvate stimulates acetoin production when glucose is present as an energy source. In Lactobacillus plantarum ATCC 8014, the energy derived from glucose via glycolysis generated a constant proton motive force of about-120 mV. At a low external pH, energized cells rapidly transported and accumulated pyruvate but did not do so when they were deenergized by nigericin. When large amounts of pyruvate were transported and subsequently accumulated internally, the cotransported protons rapidly lowered the internal pH. The conversion of pyruvate to acetoin instead of acidic end products contributed to the maintenance of pH homeostasis. This is the first report showing that the conversion of pyruvate to acetoin serves as a mechanism of pH homeostasis.

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“…Acetoin was the main end product. The synthesis of this compound is known to require a high concentration of intracellular pyruvate (39,40), which is most likely the case for our ldh null mutant.…”

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13C nuclear magnetic resonance analysis of glucose and citrate end products in an ldhL-ldhD double-knockout strain of Lactobacillus plantarum

1996

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We have examined the metabolic consequences of knocking out the two ldh genes in Lactobacillus plantarum using 13 C nuclear magnetic resonance. Unlike its wild-type isogenic progenitor, which produced lactate as the major metabolite under all conditions tested, ldh null strain TF103 mainly produced acetoin. A variety of secondary end products were also found, including organic acids (acetate, succinate, pyruvate, and lactate), ethanol, 2,3-butanediol, and mannitol.

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Relationship between pyruvate utilization and acetoin production byLactobacillus plantarum:influence of carbon source, pyruvate concentration, and metabolic inhibitors

Cited by 6 publications

References 23 publications

Dual role of alpha-acetolactate decarboxylase in Lactococcus lactis subsp. lactis

Dual role of alpha-acetolactate decarboxylase in Lactococcus lactis subsp. lactis

Conversion of Pyruvate to Acetoin Helps To Maintain pH Homeostasis in Lactobacillus plantarum

13C nuclear magnetic resonance analysis of glucose and citrate end products in an ldhL-ldhD double-knockout strain of Lactobacillus plantarum

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