Formation and stabilization of diacetyl and acetoin concentration in fully grown cultures ofStreptococcus lactis subsp. diacetylactis

Petit, Christine; Vilchez, F.; Marczak, R.

doi:10.1007/bf01026786

Cited by 15 publications

(11 citation statements)

References 13 publications

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“…A number of lines of evidence have been interpreted as indicating that lactic acid is principally derived from glucose but that diacetyl and acetoin are primary produced from citrate. Notably, (1) fermentations conducted in the absence of citrate accumulate negligible amounts of these aromatic compounds ; (2) diacetyl and acetoin have been reported to accumulate late in the fermentation period, coincident with the period after citrate catabolism has started [4]; (3) aerobic fermentations favor diacetyl and acetoin accumulation, in accord with the oxidative metabolism of citrate [5].…”

Section: Introductionmentioning

confidence: 74%

Metabolic flux in glucose/citrate co-fermentation by lactic acid bacteria as measured by isotopic ratio analysis

Goupry¹

2000

FEMS Microbiology Letters

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The flux of carbon into lactic acid, diacetyl and acetoin during the co-metabolism of glucose and citrate by Lactococcus lactis subsp. lactis biovar. diacetylactis has been determined using natural abundance isotopic ratio analysis. During fermentation in the conditions used (glucose, 27.8 mM; citric acid, 13.9 mM; initial pH 6.2^6.4, anaerobic) it is shown that approximately 65% of the carbon source used for the aroma compounds is derived from the carbohydrate. Equally, citrate contributes approximately 30% of the carbon recovered in lactic acid. Thus, there is no evidence for a metabolic separation of the catabolism of these two carbon sources. ß

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Section: Introductionmentioning

confidence: 74%

Metabolic flux in glucose/citrate co-fermentation by lactic acid bacteria as measured by isotopic ratio analysis

Goupry¹

2000

FEMS Microbiology Letters

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“…13C-NMR spectra were recorded at 125.77 MHz in 10-mm NMR tubes by using a Bruker AMX-500 spectrometer and either broadband or quadruple nuclei probe heads. Acquisition parameters were as follows for the experiments with living cells: spectral width, 38 kHz; data size, 32K; repetition delay, 1 s; pulse width, 15 [Ls (corresponding to a 600 flip angle); number of scans, 24. Proton decoupling was continuously applied by using the WALTZ sequence.…”

Section: Materuils and Methodsmentioning

confidence: 99%

¹³ C Nuclear Magnetic Resonance Studies of Citrate and Glucose Cometabolism by Lactococcus lactis

Ramos

Jordan

Cogan

et al. 1994

Appl Environ Microbiol

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13 C nuclear magnetic resonance ( 13 C-NMR) was used to investigate the metabolism of citrate plus glucose and pyruvate plus glucose by nongrowing cells of Lactococcus lactis subsp. lactis 19B under anaerobic conditions. The metabolism of citrate plus glucose during growth was also monitored directly by in vivo NMR. Although pyruvate is a common intermediate metabolite in the metabolic pathways of both citrate and glucose, the origin of the carbon atoms in the fermentation products was determined by using selectively labeled substrates, e.g., [2,4- 13 C]citrate, [3- 13 C]pyruvate, and [2- 13 C]glucose. The presence of an additional substrate caused a considerable stimulation in the rates of substrate utilization, and the pattern of end products was changed. Acetate plus acetoin and butanediol represented more than 80% (molar basis) of the end products of the metabolism of citrate (or pyruvate) alone, but when glucose was also added, 80% of the citrate (or pyruvate) was converted to lactate. This result can be explained by the activation of lactate dehydrogenase by fructose 1,6-bisphosphate, an intermediate in glucose metabolism. The effect of different concentrations of glucose on the metabolism of citrate by dilute cell suspensions was also probed by using analytical methods other than NMR. Pyruvate dehydrogenase (but not pyruvate formate-lyase) was active in the conversion of pyruvate to acetyl coenzyme A. α-Acetolactate was detected as an intermediate metabolite of citrate or pyruvate metabolism, and the labeling pattern of the end products agrees with the α-acetolactate pathway. It was demonstrated that the contribution of the acetyl coenzyme A pathway for the synthesis of diacetyl, should it exist, is lower than 10%. Evidence for the presence of internal carbon reserves in L. lactis is presented.

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“…The extent of formation of these aroma compounds depends on the L. lactis strain (7), the citrate concentration in the medium (8,18,19), the presence of hemin and/or metal ions such as Cu2+ (13), temperature and pH (20), and cell immobilization (21,22).…”

mentioning

confidence: 99%

Effect of Initial Oxygen Concentration on Diacetyl and Acetoin Production by Lactococcus lactis subsp. lactis biovar diacetylactis

Bassit

Boquien

Picque

et al. 1993

Appl Environ Microbiol

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The production of aroma compounds (acetoin and diacetyl) in fresh unripened cheese by Lactococcus lactis subsp. lactis biovar diacetylactis CNRZ 483 was studied at 30°C at different initial oxygen concentrations (0, 21, 50, and 100% of the medium saturation by oxygen). Regardless of the initial 02 concentration, maximal production of these compounds was reached only after all the citrate was consumed. Diacetyl and acetoin production was 0.01 and 2.4 mM, respectively, at 0% oxygen. Maximum acetoin concentration reached 5.4 mM at 100% oxygen. Diacetyl production was increased by factors of 2, 6, and 18 at initial oxygen concentrations of 21, 50, and 100,o respectively. The diacetylacetoin concentration ratio increased linearly with initial oxygen concentration: it was eight times higher at 100% (3.3%) than at O%o oxygen (0.4%). The effect of oxygen on diacetyl and acetoin production was also shown with other lactococci. At 01% oxygen, specific activity of a-acetolactate synthetase (0.15 U/mg) and NADH oxidase (0.04 U/mg) was 3.6 and 5.4 times lower, respectively, than at 100o oxygen. The increasing cv-acetolactate synthetase activity in the presence of oxygen would explain the higher production of diacetyl and acetoin. The NADH oxidase activity would replace the role of the lactate dehydrogenase, diacetyl reductase, and acetoin reductase in the reoxidation of NADH, allowing accumulation of these two aroma compounds.

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Formation and stabilization of diacetyl and acetoin concentration in fully grown cultures ofStreptococcus lactis subsp. diacetylactis

Cited by 15 publications

References 13 publications

Metabolic flux in glucose/citrate co-fermentation by lactic acid bacteria as measured by isotopic ratio analysis

Metabolic flux in glucose/citrate co-fermentation by lactic acid bacteria as measured by isotopic ratio analysis

¹³ C Nuclear Magnetic Resonance Studies of Citrate and Glucose Cometabolism by Lactococcus lactis

Effect of Initial Oxygen Concentration on Diacetyl and Acetoin Production by Lactococcus lactis subsp. lactis biovar diacetylactis

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Formation and stabilization of diacetyl and acetoin concentration in fully grown cultures ofStreptococcus lactis subsp. diacetylactis

Cited by 15 publications

References 13 publications

Metabolic flux in glucose/citrate co-fermentation by lactic acid bacteria as measured by isotopic ratio analysis

Metabolic flux in glucose/citrate co-fermentation by lactic acid bacteria as measured by isotopic ratio analysis

13 C Nuclear Magnetic Resonance Studies of Citrate and Glucose Cometabolism by Lactococcus lactis

Effect of Initial Oxygen Concentration on Diacetyl and Acetoin Production by Lactococcus lactis subsp. lactis biovar diacetylactis

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¹³ C Nuclear Magnetic Resonance Studies of Citrate and Glucose Cometabolism by Lactococcus lactis