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PubMed1996

Why Saccharomyces cerevisiae can oxidize but not decarboxylate external pyruvate.

Protoplasts of the yeast Saccharomyces cerevisiae oxidized externally added pyruvate by pyruvate oxidase system but were not able to decarboxylate it anaerobically by pyruvate decarboxylase at pH 6.4 in isotonic solutions. The decarboxylation set in hypotonic solutions in which the integrity of the plasma membrane was being impaired. Yeast cells incubated with [1-14C]pyruvate accumulated radioactivity under conditions allowing oxidation of pyruvate, but virtually no pyruvate was taken up when the oxidation had been arrested by inhibition or mutation. In view of a large difference between Km for pyruvate of pyruvate decarboxylase (30 mM) and of pyruvate oxidase (0.16 mM), the results may be accounted for by the assumption that transport of pyruvate across the yeast plasma membrane is trans-inhibited by relatively high concentrations of intracellular pyruvate. This arrangement would allow utilization of external pyruvate by the cell energy-transforming machinery and, at the same time, prevent its wastage by futile decarboxylation.

Decarboxylation↗

PubMed1983

Lactic acidosis, neurological deterioration and compromised cellular pyruvate oxidation due to a defect in the reoxidation of cytoplasmically generated NADH.

Two patients, one dying at 25 days and one at 20 months had 'chronic' lactic acidaemia with a high lactate to pyruvate ratio. Both showed EEG abnormalities and seizure activity and both died of respiratory failure. Investigation of cultured skin fibroblasts from these patients revealed normal pyruvate dehydrogenase and pyruvate carboxylase activities but the cells showed a decreased ability to oxidase pyruvate which was returned to normal on the addition of methylene blue. Subsequent investigations revealed that the mitochondria from the patients' cells could oxidase pyruvate normally but that the cells had an abnormal NAD to NADH ratio under standard conditions of incubation. It was concluded that both children had a redox disequilibrium in the cytoplasmic compartment due to a problem in transporting reducing equivalents from the cytoplasmic to the mitochondrial compartments.

Acidosis↗

PubMed2006

The 1',4'-iminopyrimidine tautomer of thiamin diphosphate is poised for catalysis in asymmetric active centers on enzymes.

Thiamin diphosphate, a key coenzyme in sugar metabolism, is comprised of the thiazolium and 4'-aminopyrimidine aromatic rings, but only recently has participation of the 4'-aminopyrimidine moiety in catalysis gained wider acceptance. We report the use of electronic spectroscopy to identify the various tautomeric forms of the 4'-aminopyrimidine ring on four thiamin diphosphate enzymes, all of which decarboxylate pyruvate: the E1 component of human pyruvate dehydrogenase complex, the E1 subunit of Escherichia coli pyruvate dehydrogenase complex, yeast pyruvate decarboxylase, and pyruvate oxidase from Lactobacillus plantarum. It is shown that, according to circular dichroism spectroscopy, both the 1',4'-iminopyrimidine and the 4'-aminopyrimidine tautomers coexist on the E1 component of human pyruvate dehydrogenase complex and pyruvate oxidase. Because both tautomers are seen simultaneously, these two enzymes provide excellent evidence for nonidentical active centers (asymmetry) in solution in these multimeric enzymes. Asymmetry of active centers can also be induced upon addition of acetylphosphinate, an excellent electrostatic pyruvate mimic, which participates in an enzyme-catalyzed addition to form a stable adduct, resembling the common predecarboxylation thiamin-bound intermediate, which exists in its 1',4'-iminopyrimidine form. The identification of the 1',4'-iminopyrimidine tautomer on four enzymes is almost certainly applicable to all thiamin diphosphate enzymes: this tautomer is the intramolecular trigger to generate the reactive ylide/carbene at the thiazolium C2 position in the first fundamental step of thiamin catalysis.

Binding Sites↗

PubMed1997

Cloning and phylogenetic analysis of the genes encoding acetohydroxyacid synthase from the archaeon Methanococcus aeolicus.

The gene for acetohydroxyacid synthase (AHAS) was cloned from the archaeon Methanococcus aeolicus. Contrary to biochemical studies [Xing, R. and Whitman, W.B. (1994) J. Bacteriol. 176, 1207-1213] the enzyme was encoded by two open reading frames (ORFs). Based on sequence homology, these ORFs were designated ilvB and ilvN for the large and small subunits of AHAS, respectively. A putative methanogen promoter preceded ilvB-ilvN, and a potential internal promoter was found upstream of ilvN. ilvB encoded a 65-kDa protein, which agreed well with the measured value for the purified enzyme. ilvN encoded a 19-kDa protein, which fell within the range of M(r) of small subunits from other sources. Phylogenetic analysis of the deduced amino acid sequence of ilvB showed a close relationship between the AHAS of Bacteria and Archaea, to the exclusion of other enzymes in this family, including pyruvate oxidase, glyoxylate carboligase, pyruvate decarboxylase, and the acetolactate synthase found in fermentative Bacteria. Thus, this family of enzymes probably arose prior to the divergence of the Bacteria and Archaea. Moreover, the higher plant AHAS and the red algal AHAS were related to the AHAS II of Escherichia coli and the cyanobacterial AHAS, respectively. For this reason, these genes appear to have been acquired by the Eucarya during the endosymbiosis that gave rise to the mitochondrion and chloroplast, respectively. One of the ORFs in the Methanococcus jannaschii genome possesses high similarity to the M. aeolicus ilvB, indicating that it is an authentic AHAS.

Acetolactate Synthase↗

PubMed2006

Direct kinetic evidence for half-of-the-sites reactivity in the E1 component of the human pyruvate dehydrogenase multienzyme complex through alternating sites cofactor activation.

Recent kinetic and structural studies on various thiamin-dependent enzymes, including the bacterial E1 component of the pyruvate dehydrogenase complex (PDHc), suggested an active center communication between the cofactors in these multimeric enzymes. This regulatory mode has been inferred from the dissymmetry of active sites in proteolytic patterns and X-ray structures and from a complex macroscopic kinetic behavior not being consistent with independently working active sites. Here, direct microscopic kinetic evidence for this hypothesis is presented for the alpha2beta2-type E1 component of the human pyruvate dehydrogenase complex. Only one of the two thiamin molecules bound to the two active sites is in a chemically activated state exhibiting an apparent C2 ionization rate constant of approximately 50 s(-1) at pH 7.6 and 30 degrees C, whereas the thiamin in the "inactive site" ionizes with a rate that is at least 3 orders of magnitude smaller. The chemical nonequivalence is also exhibited in the ability to bind the substrate analogue methyl acetylphosphonate and in the catalytic turnover of the substrate pyruvate in the E1-only reaction. In the activated active site, pyruvate is rapidly bound and decarboxylated with apparent forward rate constants of covalent pyruvate binding of 2 s(-1) and decarboxylation of the formed 2-lactyl-thiamin intermediate of 5 s(-1). In the dormant site, these steps are as slow as 0.03 s(-1). Under the conditions that were used, only the heterotetramer can be detected by analytical ultracentrifugation, thus ruling out the possibility that multiple oligomeric species with different reactivities cause the observed kinetic effects. The results are consistent with the recently suggested model of an active site synchronization in PDHc-E1 via a proton wire that keeps the two active sites in an alternating activation state [Frank, R. A., et al. (2004) Science 306, 872]. Kinetic studies on the related thiamin enzymes transketolase, pyruvate oxidase, and bacterial pyruvate decarboxylase are not consistent with a chemical and/or functional nonequivalence of the active sites as observed in the E1 component of hsPDHc. We hypothesize that the alternating sites reaction in PDHc-E1 aids in the synchronized acyl transfer to the E2 component in the highly organized multienzyme complex.

Amino Acid Sequence↗

PubMed1994

Electronically modulated biological functions of molecular interfaced enzymes and living cells.

Conducting polymer molecular interfaces have been implemented to modulate biological functions of fructose dehydrogenase, pyruvate oxidase and Saccharomyces cerevisiae at the electrode surface by adjustment of electrode potential. The enzyme activity of the polypyrrole-interfaced fructose dehydrogenase was electronically modulated by means of electron transfer between the enzyme and the electrode surface. The enzyme activity of polypyrrole-interfaced pyruvate oxidase was modulated by an electronically driven change of substrate concentration. The gene expression in polypyrrole-interfaced Saccharomyces cerevisiae was electronically induced by a change in the phosphate concentration.

Electrodes↗

PubMed1988

Interaction between wild-type, mutant and revertant forms of the bacterium Streptococcus sanguis and the bacterium Actinobacillus actinomycetemcomitans in vitro and in the gnotobiotic rat.

In vitro, Streptococcus sanguis inhibits the growth of Actinobacillus actinomycetemcomitans, a presumed aetiological agent of localized juvenile periodontitis. When provided with glucose and good aeration, a growing culture of Strep. sanguis was found to produce hydrogen peroxide at concentrations in excess of the maximum LD50 reported for strains of A. actinomycetemcomitans. This concentration of hydrogen peroxide also inhibits the growth of the producer organism. A mutant of Strep. sanguis was isolated that lacked the ability to produce alpha-haemolysis on blood agar. This mutant had less than 3 per cent of its parent's level of pyruvate-oxidase activity, and made no detectable hydrogen peroxide. In vitro, the mutant had also lost the ability to inhibit the growth of A. actinomycetemcomitans. A spontaneous revertant, isolated by its ability to produce alpha-haemolysis, was found to have regained parental levels of pyruvate-oxidase activity and hydrogen-peroxide production and could inhibit the growth of A. actinomycetemcomitans in vitro. A gnotobiotic rat model was used to demonstrate that Strep. sanguis and A. actinomycetemcomitans interact in vivo and that this interaction depends on hydrogen-peroxide production by Strep. sanguis.

Actinobacillus↗

PubMed1997

Bioelectrochemical determination of citric acid in real samples using a fully automated flow injection manifold.

An enzymic method for the determination of citric acid in fruits, juices and sport drinks is proposed. The method is based on the action of the enzymes citrate lyase, oxaloacetate decarboxylase and pyruvate oxidase, which convert citric acid into H2O2 with the latter being monitored amperometrically with a H2O2 probe. The enzymes pyruvate oxidase and oxaloacetate decarboxylase were immobilized. A multi-membrane system, consisting of a cellulose acetate membrane for the elimination of interferants, an enzymic membrane and a protective polycarbonate membrane were placed on a Pt electrode and used with a fully automated flow injection manifold. Several parameters were optimized, resulting in a readily constructed and reproducible biosensor. Interference from various compounds present in real samples was minimized. Calibration graphs were linear over the range 0.01-0.9 mM pyruvate, 0.015-0.6 mM oxaloacetate and 0.015-0.5 mM citrate. The throughput was 30 samples h-1 with an RSD of 1.0% (n = 8); the mean relative error was 2.4% compared with a standard method. The recovery was 96-104%. A 8-10% loss of the initial activity of the sensor was observed after 100-120 injections.

Beverages↗

PubMed1999

Prolonging cell-free protein synthesis with a novel ATP regeneration system.

A new approach for the regeneration of adenosine triphosphate (ATP) during cell-free protein synthesis was developed to prolong the synthesis and also to avoid the accumulation of inorganic phosphate. This approach was demonstrated in a batch system derived from Escherichia coli. Contrary to the conventional methods in which exogenous energy sources contain high-energy phosphate bonds, the new system was designed to generate continuously the required high-energy phosphate bonds within the reaction mixture, thereby recycling the phosphate released during protein synthesis. If allowed to accumulate, phosphate inhibits protein synthesis, most likely by reducing the concentration of free magnesium ion. Pediococcus sp. pyruvate oxidase, when introduced in the reaction mixture along with thiamine pyrophosphate (TPP) and flavin adenine dinucleotide (FAD), catalyzed the generation of acetyl phosphate from pyruvate and inorganic phosphate. Acetyl kinase, already present with sufficient activity in Escherichia coli S30 extract, then catalyzed the regeneration of ATP. Oxygen is required for the generation of acetyl phosphate and the H(2)O(2) produced as a byproduct is sufficiently degraded by endogenous catalase activity. Through the continuous supply of chemical energy, and also through the prevention of inorganic phosphate accumulation, the duration of protein synthesis is extended up to 2 h. Protein accumulation levels also increase. The synthesis of human lymphotoxin receives greater benefit than than that of chloramphenicol acetyl transferase, because the former is more sensitive to phosphate inhibition. Finally, through repeated addition of pyruvate and amino acids during the reaction period, protein synthesis continued for 6 h in the new system, resulting in a final yield of 0.7 mg/mL.

Adenosine Triphosphate↗

PubMed2001

Binding and activation of thiamin diphosphate in acetohydroxyacid synthase.

Acetohydroxyacid synthases (AHASs) are biosynthetic thiamin diphosphate- (ThDP) and FAD-dependent enzymes. They are homologous to pyruvate oxidase and other members of a family of ThDP-dependent enzymes which catalyze reactions in which the first step is decarboxylation of a 2-ketoacid. AHAS catalyzes the condensation of the 2-carbon moiety, derived from the decarboxylation of pyruvate, with a second 2-ketoacid, to form acetolactate or acetohydroxybutyrate. A structural model for AHAS isozyme II (AHAS II) from Escherichia coli has been constructed on the basis of its homology with pyruvate oxidase from Lactobacillus plantarum (LpPOX). We describe here experiments which further test the model, and test whether the binding and activation of ThDP in AHAS involve the same structural elements and mechanism identified for homologous enzymes. Interaction of a conserved glutamate with the N1' of the ThDP aminopyrimidine moiety is involved in activation of the cofactor for proton exchange in several ThDP-dependent enzymes. In accord with this, the analogue N3'-pyridyl thiamin diphosphate does not support AHAS activity. Mutagenesis of Glu47, the putative conserved glutamate, decreases the rate of proton exchange at C-2 of bound ThDP by nearly 2 orders of magnitude and decreases the turnover rate for the mutants by about 10-fold. Mutant E47A also has altered substrate specificity, pH dependence, and other changes in properties. Mutagenesis of Asp428, presumed on the basis of the model to be the crucial carboxylate ligand to Mg(2+) in the "ThDP motif", leads to a decrease in the affinity of AHAS II for Mg(2+). While mutant D428N shows ThDP affinity close to that of the wild-type on saturation with Mg(2+), D428E has a decreased affinity for ThDP. These mutations also lead to dependence of the enzyme on K(+). These experiments demonstrate that AHAS binds and activates ThDP in the same way as do pyruvate decarboxylase, transketolase, and other ThDP-dependent enzymes. The biosynthetic activity of AHAS also involves many other factors beyond the binding and deprotonation of ThDP; changes in the ligands to ThDP can have interesting and unexpected effects on the reaction.

Acetolactate Synthase↗

PubMed1979

Mechanism of L-serine oxidation in Entamoeba histolytica.

1. The enzymatic mechanism of oxygen uptake elicited by L-serine in axenically cultivated trophozoites of Entamoeba histolytica was investigated. 2. Of 22 amino acids examined, only L-serine stimulated oxygen consumption by intact and disrupted amoebae. 3. Pyruvate, a product of serine metabolism, also stimulated oxygen consumption in the amoebae. 4. Characterization of the oxygen uptake elicited by both L-serine and pyruvate, and analysis of the products of L-serine metabolism indicate that the amino acid is first converted to pyruvate. 5. L-Serine dehydratase, which catalyzes the deamination of serine to pyruvate, was detected primarily in the soluble fraction of the amoebae. D-Serine potently inhibited the enzyme, as well as oxygen uptake in the presence of L-serine but not in the presence of pyruvate. 6. The pyruvate formed is oxidized, at least in part, by a novel pyruvate oxidase involving the uptake of molecular oxygen.

Acetyl Coenzyme A↗

PubMed1997

2-Oxo-3-alkynoic acids, universal mechanism-based inactivators of thiamin diphosphate-dependent decarboxylases: synthesis and evidence for potent inactivation of the pyruvate dehydrogenase multienzyme complex.

A new class of compounds, the 2-oxo-3-alkynoic acids with a phenyl substituent at carbon 4 was reported by the authors as potent irreversible and mechanism-based inhibitors of the thiamin diphosphate- (ThDP-) dependent enzyme pyruvate decarboxylase [Chiu, C.-F., & Jordan, F. (1994) J. Org. Chem. 59, 5763-5766]. The method has been successfully extended to the synthesis of the 4-, 5-, and 7-carbon aliphatic members of this family of compounds. These three compounds were then tested on three ThDP-dependent pyruvate decarboxylases: the Escherichia coli pyruvate dehydrogenase multienzyme complex (PDHc) and its E1 (ThDP-dependent) component, pyruvate oxidase (POX, phosphorylating; from Lactobacillus plantarum),and pyruvate decarboxylase (PDC) from Saccharomycescerevisiae. All three enzymes were irreversibly inhibited by the new compounds. The 4-carbon acid is the best substrate-analog inactivator known to date for PDHc, more potent than either fluoropyruvate or bromopyruvate. The following conclusions were drawn from extensive studies with PDHc: (a) The kinetics of inactivation of PDH complexes and of resolved E1 by 2-oxo-3-alkynoic acids is time- and concentration-dependent. (b) The 4-carbon acid has a Ki 2 orders of magnitude stronger than the 5-carbon acid, clearly demonstrating the substrate specificity of PDHc. (c) The rate of inactivation of PDH complexes and of resolved E1 by 2-oxo-3-alkynoic acids is enhanced by the addition of ThDP and MgCl2. (d) Pyruvate completely protects E1 and partially protects PDHc from inactivation by 2-oxo-3-butynoic acid. (e) E1 but not E2-E3 is the target of inactivation by 2-oxo-3-butynoic acid. (f) Inactivation of E1 by 2-oxo-3-butynoic acid is accompanied by modification of 1.3 cysteines/E1 monomer. The order of reactivity with the 4-carbon acid was PDHc > POX > PDC. While the order of reactivity with PDHc and POX was 2-oxo-3-butynoic acid > 2-oxo-3-pentynoic acid > 2-oxo-3-heptynoic acid, the order of reactivity was reversed with PDC.

Bacterial Proteins↗

PubMed2000

Operation of a miniature redox hydrogel-based pyruvate sensor in undiluted deoxygenated calf serum.

An amperometric sensor for the detection of pyruvate in biological fluids was formed by modifying the tip of a 0.25 mm gold wire with a layer of electrically "wired" recombinant pyruvate oxidase (POP). The sensor did not require O2 for its operation. The electroactive area of the tip of the microwire was increased by electrodeposition of platinum black. The POP was adsorbed on the platinum black and then "wired" with the cross-linked, subsequently deposited poly(4-vinylpyridine), part of the pyridine functions of which were complexed with [Os(bpy)2Cl](+/2+) and part quaternized with 2-bromoethylamine. In the resulting thin layer the POP was well "wired". When the electrode was poised at 0.4 V vs Ag/ AgCl, the sensitivity at pH 6 was 0.26 A cm(-2) M(-1) and the current increased linearly with the pyruvate concentration through the 2 x 10(-6) - 6 x 10(-4) M range. Thiamine diphosphate, flavin adenine dinucleotide, and MgCl2 were not required for the assay, but stabilized the stored enzyme electrode. Placement of a dialysis membrane (MWCO 3500) on the electrode alleviated the severe interference of ascorbate. In calf serum, the detection limit was 30 microM, suggesting that the electrode might be used in the continuous monitoring of pyruvate in hypoxic organs.

Animals↗

PubMed1987

Oxygen uptake activity and aerobic metabolism of Streptococcus thermophilus STH450.

Streptococcus thermophilus STH450 had a very high oxygen uptake. This strain was then compared with aerobic metabolism to S. thermophilus ATCC 19258, a reference strain for aerobic metabolism. Molecular oxygen, which was absorbed by S. thermophilus STH450 during aerobic glycolytic metabolism, was involved in the oxidation of NADH by the catalytic activity of NADH oxidase. The portion of pyruvate that corresponded to the oxidized NADH was committed to form alpha-acetolactate, acetoin, and diacetyl. Both strains were deficient in peroxidase and pyruvate oxidase activities; therefore, NADH oxidase was probably the terminal oxidase in aerobic glycolytic metabolism. Oxygen uptake and NADH oxidase activities were significantly higher in S. thermophilus STH450 than in S. thermophilus ATCC 19258. alpha-Acetolactate, acetoin, and diacetyl also accumulated during aerobic glycolytic metabolism of S. thermophilus STH450. However, when both strains were grown in the presence of pyruvate, these metabolites were equivalent. Hence, less oxygen might be needed for pyruvate metabolism.

Animals↗

PubMed2003

Redox-triggered FTIR difference spectra of FAD in aqueous solution and bound to flavoproteins.

Flavin adenine dinucleotide (FAD) and three different flavoproteins in aqueous solution were subjected to redox-triggered Fourier transform infrared difference spectroscopy. The acquired vibrational spectra show a great number of positive and negative peaks, pertaining to the oxidized and reduced state of the molecule, respectively. Density functional theory calculations on the B3LYP/6-31G(d) level were employed to assign several of the observed bands to vibrational modes of the isoalloxazine moiety of the flavin cofactor in both its oxidized and, for the first time, its reduced state. Prominent modes measured for oxidized FAD include nu(C(4)=O) and nu(C(2)=O) at 1716 and 1674 cm(-1), respectively, nu(C(4a)=N(5)) at 1580 cm(-1), and nu(C(10a)=N(1)) at 1548 cm(-1). Measured modes of the reduced form of FAD include nu(C(2)=O) at 1692 cm(-1), nu(C(4)=O) at 1634 cm(-1), and nu(C(4a)=C(10a)) at 1600 cm(-1). While the overall shape of the enzyme spectra is similar to the shape of the spectrum of free FAD, there are numerous differences in detail. In particular, the nu(C=N) modes of the flavin exhibit frequency shifts in the protein-bound form, most prominently for pyruvate oxidase where nu(C(10a)=N(1)) downshifts by 14 cm(-1) to 1534 cm(-1). The significance of this shift and a possible explanation in connection with the bent conformation of the flavin cofactor in this enzyme are discussed.

Animals↗

PubMed1986

Single-enzyme-based amperometric assay for phosphate ion.

An amperometric assay for phosphate ion, using a single enzymatic process, has been developed. The enzyme used was pyruvate oxidase, which catalyzes the oxidation of pyruvate in the presence of oxygen and phosphate ion. The products of the enzymatic reaction are acetyl phosphate, carbon dioxide, and hydrogen peroxide. The latter was monitored by means of a hydrogen peroxide electrode and an oxidase meter. Phosphate ion in the concentration range of 50-500 microM can be measured within 4 min. Anions, such as pyrophosphate, sulfate, nitrate, nitrite, and acetate, gave only marginal responses.

Electrochemistry↗

PubMed1975

The pyruvate-dehydrogenase complex from Azotobacter vinelandii.

The pyruvate dehydrogenase complex from Axotobacter vinelandii was isolated in a five-step procedure. The minimum molecular weight of the pure complex is 600,000, as based on an FAD content of 1.6 nmol-mg protein-1. The molecular weight is 1.0-1.2 X 10(6), indicating 1 mole of lipoamide dehydrogenase dimer per complex molecule. Sodium dodecylsulphate gel electrophoretical patterns show that apart from pyruvate dehydrogenase (Mr89,000) and lipoamide dehydrogenase (Mrmonomer 56,000) two active transacetylase isoenzymes are present with molecular weight on the gel 82,000 and 59,000 but probably actually lower. The pure complex has a specific activity of the pyruvate-NAD+ reductase (overall) reaction of 10 units-mg protein-1 at 25 degrees C. The partial reactions have the following specific activities in units-mg protein-1 at 25 degrees C under standard conditions: pyruvate-K3Fe(CN)6 reductase 0.14, transacetylase 3.6 and lipoamide dehydrogenase 2.9. The properties of this complex are compared with those from other sources. NADPH reduced the FAD of lipoamide dehydrogenase as well in the complex as in the free form. NADP+ cannot be used as electron acceptor. Under aerobic conditios pyruvate oxidase reaction, dependent on Mg2+ and thiamine pyrophosphate, converts pyruvate into CO2 and acetate; V is 0.2 mumol 02-min-1-mg-1, Km(pyruvate)0.3 mM. The kinetics of this reaction shows a linear 1/velocity-1/[pyruvate] plot. K3Fe(CN)6 competes with the oxidase reaction. The oxidase activity is stimulated by AMP and sulphate and is inhibited by acetyl-CoA. The partially purified enzyme contains considerable phosphotransacetylase activity. The pure complex does not contain this activity. The physiological significance of this activity is discussed.

Acetyltransferases↗

PubMed1983

Metabolism of pyruvate and citrate in lactobacilli.

Lactobacillus acidophilus, L. bulgaricus, L. casei, L. delbrueckii , L. lactis and L. plantarum contained a pyruvate oxidase for the oxidation of pyruvate to acetyl phosphate and acetate. The presence of an acetate kinase converted the acetyl phosphate to acetate. L. casei and L. plantarum produced lactate and acetoin, in addition to acetate, under the conditions used while L. casei also produced diacetyl. L. casei and L. plantarum were the only species to utilize citrate. L. helveticus and L. helveticus subsp. jugurti did not utilize pyruvate under the conditions used.

Citrates↗