Effect of temperature on diacetyl and acetoin production byLactococcus lactissubsp.lactisbiovardiacetilactisCNRZ 483

Bassit, N.; Boquien, Clair‐Yves; Picque, Daniel; Corrieu, Georges

doi:10.1017/s0022029900033732

Cited by 41 publications

(37 citation statements)

References 18 publications

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“…Compounds of the acetoin pathway were more abundant on lactose, a slowly catabolized sugar in this strain lacking the PTS lac and tagatose pathway (13), than on glucose, irrespective of the strain. Moreover, this metabolic pathway was strongly stimulated by aerobiosis (Table 2) (3,10).…”

Section: Resultsmentioning

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: Resultsmentioning

confidence: 99%

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

et al. 1997

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“…L. lactis is an aerotolerant lactic acid bacterium that contains NADH oxidases (encoded by the noxC, noxD, noxE genes [8]) that protect the cell during aerobic growth (11). NOX enzymes catalyze oxidation of NADH to NAD ϩ by molecular oxygen and are induced under aerobic conditions (7,23,38). The combination of PDH and NOX enzymes could account for the conversion of pyruvate to acetyl-CoA under the conditions of the experiment.…”

Section: Discussionmentioning

confidence: 99%

Citrate Uptake in Exchange with Intermediates in the Citrate Metabolic Pathway in Lactococcus lactis IL1403

Pudlik

Lolkema

2011

J Bacteriol

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Carbohydrate/citrate cometabolism in Lactococcus lactis results in the formation of the flavor compound acetoin. Resting cells of strain IL1403(pFL3) rapidly consumed citrate while producing acetoin when substoichiometric concentrations of glucose or L-lactate were present. A proton motive force was generated by electrogenic exchange of citrate and lactate catalyzed by the citrate transporter CitP and proton consumption in decarboxylation reactions in the pathway. In the absence of glucose or L-lactate, citrate consumption was biphasic. During the first phase, hardly any citrate was consumed. In the second phase, citrate was converted rapidly, but without the formation of acetoin. Instead, significant amounts of the intermediates pyruvate and ␣-acetolactate, and the end product acetate, were excreted from the cells. It is shown that the intermediates and acetate are excreted in exchange with the uptake of citrate catalyzed by CitP. The availability of exchangeable substrates in the cytoplasm determines both the rate of citrate consumption and the end product profile. It follows that citrate metabolism in L. lactis IL1403(pFL3) splits up in two routes after the formation of pyruvate, one the well-characterized route yielding acetoin and the other a new route yielding acetate. The flux distribution between the two branches changes from 85:15 in the presence of L-lactate to 30:70 in the presence of pyruvate. The proton motive force generated was greatest in the presence of L-lactate and zero in the presence of pyruvate, suggesting that the pathway to acetate does not generate proton motive force.

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“…Acetoin and diacetyl were also found to be produced in different concentrations. These two metabolites are produced in small concentrations during the citrate metabolism and they are very important flavoring components in the fermented products (Bassit et al 1993). …”

Section: Organic Acids Production During Fermentationsmentioning

confidence: 99%

Synbiotic functional drink from Jerusalem artichoke juice fermented by probiotic Lactobacillus plantarum PCS26

et al. 2015

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A probiotic strain Lactobacillus plantarum PCS26 was used to ferment Jerusalem artichoke juice. Growth kinetics of the bacterial strain was followed during juice fermentation both in flask and in laboratory fermentor. Jerusalem artichoke showed to be an excellent source of nutrients for L. plantarum PCS26 growth. The culture grew very well reaching more than 10 10 cfu/ml in just 12 h. The pH changed from the initial 6.5 to 4.6 at the end of fermentation. The culture hydrolyzed fructooligosaccharides present in the Jerusalem artichoke juice, yielding fructose which was presumably consumed along with the malic acid as energy and carbon source. Lactic acid was the main metabolite produced in concentration of 4.6 g/L. Acetic and succinic acid were also identified. Sensory evaluation of the fermented Jerusalem artichoke juice and its mixtures with blueberry juice showed that the 50/50 % v/v mixture would be very well accepted by the consumers. Above 80 % of the panelists would buy this drink, and over 60 % were willing to pay more for it. Culture survivability in the fermented juices during storage at 4-7°C was assayed by the Weibullian model. The product shelf-life was extended from 19.70 ± 0.50 days of pure Jerusalem artichoke juice to 35.7 ± 6.4 days of the mixture containing 30 % blueberry juice.

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Effect of temperature on diacetyl and acetoin production byLactococcus lactissubsp.lactisbiovardiacetilactisCNRZ 483

Cited by 41 publications

References 18 publications

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

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

Citrate Uptake in Exchange with Intermediates in the Citrate Metabolic Pathway in Lactococcus lactis IL1403

Synbiotic functional drink from Jerusalem artichoke juice fermented by probiotic Lactobacillus plantarum PCS26

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