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Ion-selective electrode integrated in small-scale bioreactor for continuous intracellular pH determination in Lactobacillus plantarum. Folia Microbiol (Praha) 2019; 65:467-473. [PMID: 31468368 DOI: 10.1007/s12223-019-00749-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2019] [Accepted: 08/20/2019] [Indexed: 01/24/2023]
Abstract
The aim of the present study was to develop an ion-selective electrode method for the continuous determination of the intracellular pH in Lactobacillus plantarum using a small-scale bioreactor. This method employed a salicylate-selective electrode basing on the distribution of salicylic acid across the cytoplasmic membrane. This developed electrode responded to salicylate concentrations above 20 μmol/L with a Nernstian sensitivity. The energized and concentrated cells were added into a thermostated small-scale bioreactor that contained the salicylate anions dissolved in a 100 mmol/L potassium phosphate buffer at different pH values. The changes in salicylate concentration that occurred in the medium containing bacterial suspension were measured as a voltage change. The cells of Lactobacillus plantarum showed maintenance of pH homeostasis at the studied pH ranging from 4.0 to 7.0, and they kept a neutral intracellular pH up to 5.8. The simplicity of the measuring preparation and the relatively low cellular concentration, as well as the advantages of the small-scale bioreactor, lead us to believe that the described method can facilitate the study of the physicochemical factors on the intracellular pH of lactic acid bacteria using a single pH probe in one method.
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Effect of pH and dilution rate on specific production rate of extra cellular metabolites by Lactobacillus salivarius UCO_979C in continuous culture. Appl Microbiol Biotechnol 2015; 99:6417-29. [PMID: 25805342 DOI: 10.1007/s00253-015-6526-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2014] [Revised: 03/04/2015] [Accepted: 03/07/2015] [Indexed: 10/23/2022]
Abstract
The effect of pH and dilution rate on the production of extracellular metabolites of Lactobacillus salivarius UCO_979 was studied. The experiments were carried out in continuous mode, with chemically defined culture medium at a temperature of 37 °C, 200 rpm agitation and synthetic air flow of 100 ml/min. Ethanol, acetic acid, formic acid, lactic acid and glucose were quantified through HPLC, while exopolysaccharide (EPS) was extracted with ethanol and quantified through the Dubois method. The results showed no linear trends for the specific production of lactic acid, EPS, acetic acid and ethanol, while the specific glucose consumption and ATP production rates showed linear trends. There was a metabolic change of the strain for dilution rates below 0.3 h(-1). The pH had a significant effect on the metabolism of the strain, which was evidenced by a higher specific glucose consumption and increased production of ATP at pH 6 compared with that obtained at pH 7. This work shows not only the metabolic capabilities of L. salivarius UCO_979C, but also shows that it is possible to quantify some molecules associated with its current use as gastrointestinal probiotic, especially regarding the production of organic acids and EPS.
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3
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Alfano A, Donnarumma G, Cimini D, Fusco A, Marzaioli I, De Rosa M, Schiraldi C. Lactobacillus plantarum: Microfiltration experiments for the production of probiotic biomass to be used in food and nutraceutical preparations. Biotechnol Prog 2015; 31:325-33. [DOI: 10.1002/btpr.2037] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Revised: 12/09/2014] [Indexed: 12/17/2022]
Affiliation(s)
- Alberto Alfano
- Dept. of Experimental Medicine; Second University of Naples; via De Crecchio n°7 80138 Naples Italy
| | - Giovanna Donnarumma
- Dept. of Experimental Medicine; Second University of Naples; via De Crecchio n°7 80138 Naples Italy
| | - Donatella Cimini
- Dept. of Experimental Medicine; Second University of Naples; via De Crecchio n°7 80138 Naples Italy
| | - Alessandra Fusco
- Dept. of Experimental Medicine; Second University of Naples; via De Crecchio n°7 80138 Naples Italy
| | - Iolanda Marzaioli
- Dept. of Experimental Medicine; Second University of Naples; via De Crecchio n°7 80138 Naples Italy
| | - Mario De Rosa
- Dept. of Experimental Medicine; Second University of Naples; via De Crecchio n°7 80138 Naples Italy
| | - Chiara Schiraldi
- Dept. of Experimental Medicine; Second University of Naples; via De Crecchio n°7 80138 Naples Italy
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Lactate racemase is a nickel-dependent enzyme activated by a widespread maturation system. Nat Commun 2014; 5:3615. [PMID: 24710389 PMCID: PMC4066177 DOI: 10.1038/ncomms4615] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Accepted: 03/11/2014] [Indexed: 02/02/2023] Open
Abstract
Racemases catalyze the inversion of stereochemistry in biological molecules, giving the organism the ability to use both isomers. Among them, lactate racemase remains unexplored due to its intrinsic instability and lack of molecular characterization. Here we determine the genetic basis of lactate racemization in Lactobacillus plantarum. We show that, unexpectedly, the racemase is a nickel-dependent enzyme with a novel α/β fold. In addition, we decipher the process leading to an active enzyme, which involves the activation of the apo-enzyme by a single nickel-containing maturation protein that requires preactivation by two other accessory proteins. Genomic investigations reveal the wide distribution of the lactate racemase system among prokaryotes, showing the high significance of both lactate enantiomers in carbon metabolism. The even broader distribution of the nickel-based maturation system suggests a function beyond activation of the lactate racemase and possibly linked with other undiscovered nickel-dependent enzymes.
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5
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Tan P, Peh K, Gan C, Liong M. Bioactive dairy ingredients for food and non-food applications. ACTA ALIMENTARIA 2014. [DOI: 10.1556/aalim.43.2014.1.12] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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6
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Channel-mediated lactic acid transport: a novel function for aquaglyceroporins in bacteria. Biochem J 2013; 454:559-70. [DOI: 10.1042/bj20130388] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
MIPs (major intrinsic proteins), also known as aquaporins, are membrane proteins that channel water and/or uncharged solutes across membranes in all kingdoms of life. Considering the enormous number of different bacteria on earth, functional information on bacterial MIPs is scarce. In the present study, six MIPs [glpF1 (glycerol facilitator 1)–glpF6] were identified in the genome of the Gram-positive lactic acid bacterium Lactobacillus plantarum. Heterologous expression in Xenopus laevis oocytes revealed that GlpF2, GlpF3 and GlpF4 each facilitated the transmembrane diffusion of water, dihydroxyacetone and glycerol. As several lactic acid bacteria have GlpFs in their lactate racemization operon (GlpF1/F4 phylogenetic group), their ability to transport this organic acid was tested. Both GlpF1 and GlpF4 facilitated the diffusion of D/L-lactic acid. Deletion of glpF1 and/or glpF4 in Lb. plantarum showed that both genes were involved in the racemization of lactic acid and, in addition, the double glpF1 glpF4 mutant showed a growth delay under conditions of mild lactic acid stress. This provides further evidence that GlpFs contribute to lactic acid metabolism in this species. This lactic acid transport capacity was shown to be conserved in the GlpF1/F4 group of Lactobacillales. In conclusion, we have functionally analysed the largest set of bacterial MIPs and demonstrated that the lactic acid membrane permeability of bacteria can be regulated by aquaglyceroporins.
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7
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Aerobic metabolism and oxidative stress tolerance in the Lactobacillus plantarum group. World J Microbiol Biotechnol 2013; 29:1713-22. [DOI: 10.1007/s11274-013-1334-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Accepted: 03/22/2013] [Indexed: 11/25/2022]
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8
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Hydrogenase activity and proton-motive force generation by Escherichia coli during glycerol fermentation. J Bioenerg Biomembr 2012; 45:253-60. [DOI: 10.1007/s10863-012-9498-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2012] [Accepted: 12/09/2012] [Indexed: 01/23/2023]
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9
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Quatravaux S, Remize F, Bryckaert E, Colavizza D, Guzzo J. Examination of Lactobacillus plantarum lactate metabolism side effects in relation to the modulation of aeration parameters. J Appl Microbiol 2007; 101:903-12. [PMID: 16968302 DOI: 10.1111/j.1365-2672.2006.02955.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIMS The characterization of global aerobic metabolism of Lactobacillus plantarum LP652 under different aeration levels, in order to optimize acetate production kinetics and to suppress H2O2 toxicity. METHODS AND RESULTS Cultures of L. plantarum were grown on different aeration conditions. After sugar exhaustion and in the presence of oxygen, lactate was converted to acetate, H2O2 and carbon dioxide with concomitant ATP production. Physiological assays were performed at selected intervals in order to assess enzyme activity and vitality of the strain during lactic acid conversion. The maximal aerated condition led to fast lactate-to-acetate conversion kinetics between 8 and 12 h, but H2O2 immediately accumulated, thus affecting cell metabolism. Pyruvate oxidase activity was highly enhanced by oxygen tension and was responsible for H2O2 production after 12 h of culture, whereas lactate oxidase and NADH-dependent lactate dehydrogenase activities were not correlated to metabolite production. Limited NADH oxidase (NOX) and NADH peroxidase (NPR) activities were probably responsible for toxic H2O2 levels in over-aerated cultures. CONCLUSION Modulating initial airflow led to the maximal specific activity of NOX and NPR observed after 24 h of culture, thus promoting H2O2 destruction and strain vitality at the end of the process. SIGNIFICANCE AND IMPACT OF THE STUDY Optimal aeration conditions were determined to minimize H2O2 concentration level during growth on lactate.
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Affiliation(s)
- S Quatravaux
- Laboratoire de Microbiologie UMR UB/INRA 1232, ENSBANA, Dijon, France
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10
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Barthelmebs L, Divies C, Cavin JF. Knockout of the p-coumarate decarboxylase gene from Lactobacillus plantarum reveals the existence of two other inducible enzymatic activities involved in phenolic acid metabolism. Appl Environ Microbiol 2000; 66:3368-75. [PMID: 10919793 PMCID: PMC92157 DOI: 10.1128/aem.66.8.3368-3375.2000] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lactobacillus plantarum NC8 contains a pdc gene coding for p-coumaric acid decarboxylase activity (PDC). A food grade mutant, designated LPD1, in which the chromosomal pdc gene was replaced with the deleted pdc gene copy, was obtained by a two-step homologous recombination process using an unstable replicative vector. The LPD1 mutant strain remained able to weakly metabolize p-coumaric and ferulic acids into vinyl derivatives or into substituted phenyl propionic acids. We have shown that L. plantarum has a second acid phenol decarboxylase enzyme, better induced with ferulic acid than with p-coumaric acid, which also displays inducible acid phenol reductase activity that is mostly active when glucose is added. Those two enzymatic activities are in competition for p-coumaric and ferulic acid degradation, and the ratio of the corresponding derivatives depends on induction conditions. Moreover, PDC appeared to decarboxylate ferulic acid in vitro with a specific activity of about 10 nmol. min(-1). mg(-1) in the presence of ammonium sulfate. Finally, PDC activity was shown to confer a selective advantage on LPNC8 grown in acidic media supplemented with p-coumaric acid, compared to the LPD1 mutant devoid of PDC activity.
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Affiliation(s)
- L Barthelmebs
- Laboratoire de Microbiologie UMR-INRA, ENSBANA, Université de Bourgogne, Dijon, France
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11
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Glaasker E, Konings WN, Poolman B. The application of pH-sensitive fluorescent dyes in lactic acid bacteria reveals distinct extrusion systems for unmodified and conjugated dyes. Mol Membr Biol 1996; 13:173-81. [PMID: 8905646 DOI: 10.3109/09687689609160594] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Intracellular pH in bacteria can be measured efficiently between internal pH values of 6.5 and 8.5 with the fluorescent pH indicator 2',7'-bis-(2-carboxyethyl)-5[and-6]-carboxyfluorescein (BCECF). A new fluorescent pH probe with a lower pKa(app) than BCECF was synthesized from fluorescein isothiocyanate and glutamate. The new probe, N-(fluorescein thio-ureanyl)-glutamate (FTUG), was much less sensitive to changes in concentrations of KCl than was BCECF. Similar to BCECF, an efflux of FTUG independent of the proton motive force, but dependent on ATP, was observed both in Lactobacillus plantarum and Lactococcus lactis. Corrections for probe efflux allowed accurate measurements of the pHin. Similar intracellular pH values were determined with FTUG and BCECF, in the range where both probes can be applied, and the pH values correlated well with those estimated from the distribution of radio-labelled benzoic acid. Since FITC can easily be coupled to substrates containing an amino group, it is possible to develop other FITC derivatives as well. The mechanisms of probe excretion and the nature of the excreted product(s) were studied in further detail for BCECF and FTUG. BCECF was excreted from wild-type L. lactis in an unmodified form as was determined by chromatographic and mass spectrometry analysis. In the case of FTUG, the excreted product was a conjugated derivative. Unmodified FTUG was not excreted, although it was present in cellular extracts from L. lactis. Exit of BCECF was completely inhibited in a BCECF efflux mutant (Bef-) of L. lactis, whereas FTUG-conjugate efflux in this mutant was similar to the wild-type. Addition of indomethacin, a known inhibitor of BCECF efflux in human epithelial cells, resulted in complete inhibition of BCECF efflux in wild-type L. lactis, whereas FTUG-conjugate exit was only slightly affected. The results of the mutant and inhibitor studies suggest that FTUG-conjugate and BCECF efflux in L. lactis are mediated by different ATP-driven extrusion systems for organic anions.
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Affiliation(s)
- E Glaasker
- Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren, The Netherlands
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12
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Glaasker E, Konings WN, Poolman B. Osmotic regulation of intracellular solute pools in Lactobacillus plantarum. J Bacteriol 1996; 178:575-82. [PMID: 8550485 PMCID: PMC177697 DOI: 10.1128/jb.178.3.575-582.1996] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Bacteria respond to changes in medium osmolarity by varying the concentrations of specific solutes in order to maintain constant turgor pressure. The cytoplasmic pools of K+, proline, glutamate, alanine, and glycine of Lactobacillus plantarum ATCC 14917 increased when the osmolarity of the growth media was raised from 0.20 to 1.51 osmol/kg by KCL. When glycine-betaine was present in a high-osmolarity chemically defined medium, it was accumulated to a high cytoplasmic concentration, while the concentrations of most other osmotically important solutes decreased. These observations, together with the effects of glycine-betaine on the specific growth rate under high-osmolarity conditions, suggest that glycine-betaine is preferentially accumulated in L. plantarum. Uptake of glycine-betaine, proline, glutamate, and alanine was studied in cells that were alternately exposed to hyper- and hypo-osmotic stresses. The rate of uptake of proline and glycine-betaine increased instantaneously upon increasing the osmolarity, whereas that of other amino acids did not. This activation occurred also under conditions in which protein synthesis was inhibited was most pronounced when cells were pregrown at high osmolarity. The duration of net transport was a function of the osmotic strength of the assay medium. Glutamate uptake was not activated by an osmotic upshock, and the uptake of alanine was low under all conditions tested. When cells were subjected to osmotic downshock, a rapid efflux of accumulated glycine-betaine, proline, and alanine occurred whereas the pools of other amin acids remained unaffected. The results indicate that osmolyte efflux is, at least to some extent, mediated via specific osmotically regulated efflux systems and not via nonspecific mechanisms as has been suggested previously.
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Affiliation(s)
- E Glaasker
- Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren, The Netherlands
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14
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ter Steeg P, Pieterman F, Hellemons J. Effects of air/nitrogen, temperature and pH on energy-dependent growth and survival of Listeria innocua in continuous culture and water-in-oil emulsions. Food Microbiol 1995. [DOI: 10.1016/s0740-0020(95)80132-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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15
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Montville TJ, Bruno ME. Evidence that dissipation of proton motive force is a common mechanism of action for bacteriocins and other antimicrobial proteins. Int J Food Microbiol 1994; 24:53-74. [PMID: 7703030 DOI: 10.1016/0168-1605(94)90106-6] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
While bacteriocins from lactic acid bacteria (LAB) have generated tremendous interest among food microbiologists, they are not unique. The biosphere is awash with antimicrobial proteins such as colicins, defensins, cecropins, and magainins. These proteins share many characteristics. They are low molecular weight, cationic, amphiphilic, tend to aggregate and are benign to the producing organism. In cases where the mode of action has been investigated, the cell membrane appears to be the site of action. There is increasing evidence that bacteriocins from many bacterial genera also share these characteristics. After a brief introduction on the significance of LAB bacteriocins, this review provides some background on proton motive force. Current studies of mechanisms for various bacteriocins are reviewed. Evidence is then introduced that bacteriocins produced by lactic acid bacteria act by the common mechanism of depleting proton motive force. The role and importance of energized membranes in this process is examined. These observations are linked to literature which demonstrates that many other classes of antimicrobial proteins act by the same mechanism. Questions regarding the role of receptor proteins and the physical mechanism by which PMF is depleted remain unresolved.
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Affiliation(s)
- T J Montville
- New Jersey Agricultural Experiment Station, Department of Food Science, Cook College, Rutgers, State University of New Jersey, New Brunswick 08903-0231
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16
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Ferain T, Garmyn D, Bernard N, Hols P, Delcour J. Lactobacillus plantarum ldhL gene: overexpression and deletion. J Bacteriol 1994; 176:596-601. [PMID: 8300514 PMCID: PMC205095 DOI: 10.1128/jb.176.3.596-601.1994] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Lactobacillus plantarum is a lactic acid bacterium that converts pyruvate to L-(+)- and D-(-)-lactate with stereospecific enzymes designated L-(+)- and D-(-)-lactate dehydrogenase (LDH), respectively. A gene (designated ldhL) that encodes L-(+)-lactate dehydrogenase from L. plantarum DG301 was cloned by complementation in Escherichia coli. The nucleotide sequence of the ldhL gene predicted a protein of 320 amino acids closely related to that of Lactobacillus pentosus. A multicopy plasmid bearing the ldhL gene without modification of its expression signals was introduced in L. plantarum. L-LDH activity was increased up to 13-fold through this gene dosage effect. However, this change had hardly any effect on the production of L-(+)- and D-(-)-lactate. A stable chromosomal deletion in the ldhL gene was then constructed in L. plantarum by a two-step homologous recombination process. Inactivation of the gene resulted in the absence of L-LDH activity and in exclusive production of the D isomer of lactate. However, the global concentration of lactate in the culture supernatant remained unchanged.
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Affiliation(s)
- T Ferain
- Laboratoire de Génétique Moléculaire, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
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Loubiere P, Salou P, Leroy MJ, Lindley ND, Pareilleux A. Electrogenic malate uptake and improved growth energetics of the malolactic bacterium Leuconostoc oenos grown on glucose-malate mixtures. J Bacteriol 1992; 174:5302-8. [PMID: 1644757 PMCID: PMC206366 DOI: 10.1128/jb.174.16.5302-5308.1992] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Growth of the malolactic bacterium Leuconostoc oenos was improved with respect to both the specific growth rate and the biomass yield during the fermentation of glucose-malate mixtures as compared with those in media lacking malate. Such a finding indicates that the malolactic reaction contributed to the energy budget of the bacterium, suggesting that growth is energy limited in the absence of malate. An energetic yield (YATP) of 9.5 g of biomass.mol ATP-1 was found during growth on glucose with an ATP production by substrate-level phosphorylation of 1.2 mol of ATP.mol of glucose-1. During the period of mixed-substrate catabolism, an apparent YATP of 17.7 was observed, indicating a mixotrophy-associated ATP production of 2.2 mol of ATP.mol of glucose-1, or more correctly an energy gain of 0.28 mol of ATP.mol of malate-1, representing proton translocation flux from the cytoplasm to the exterior of 0.56 or 0.84 H+.mol of malate-1(depending on the H+/ATP stoichiometry). The growth-stimulating effect of malate was attributed to chemiosmotic transport mechanisms rather than proton consumption by the malolactic enzyme. Lactate efflux was by electroneutral lactate -/H+ symport having a constant stoichiometry, while malate uptake was predominantly by a malate -/H+ symport, though a low-affinity malate- uniport was also implicated. The measured electrical component (delta psi) of the proton motive force was altered, passing from -30 to -60 mV because of this translocation of dissociated organic acids when malolactic fermentation occurred.
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Affiliation(s)
- P Loubiere
- Département de Génie Biochimique, Centre National de la Recherche Scientifique Unité de Recherche Associée, Toulouse, France
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18
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Pyruvate is transported by a proton symport inLactobacillus plantarum 8014. Curr Microbiol 1992. [DOI: 10.1007/bf01570082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Tsau JL, Guffanti AA, Montville TJ. Conversion of Pyruvate to Acetoin Helps To Maintain pH Homeostasis in
Lactobacillus plantarum. Appl Environ Microbiol 1992; 58:891-4. [PMID: 16348677 PMCID: PMC195350 DOI: 10.1128/aem.58.3.891-894.1992] [Citation(s) in RCA: 83] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
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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Affiliation(s)
- J L Tsau
- Department of Food Science, New Jersey Agricultural Experiment Station, Cook College, Rutgers-the State University, New Brunswick, New Jersey 08903-0231, and Department of Biochemistry, Mount Sinai School of Medicine of the City University of New York, New York, New York 10029
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20
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Lewus CB, Sun S, Montville TJ. Production of an Amylase-Sensitive Bacteriocin by an Atypical
Leuconostoc paramesenteroides
Strain. Appl Environ Microbiol 1992; 58:143-9. [PMID: 16348619 PMCID: PMC195184 DOI: 10.1128/aem.58.1.143-149.1992] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An atypical
Leuconostoc paramesenteroides
strain isolated from retail lamb produced a bacteriocin, leuconocin S, that was inactivated by α-amylase, trypsin, α-chymotrypsin, protease, and proteinase K but not by lipase or heat treatment at 60°C for 30 min. Supernatants from culture broths produced two glycoprotein bands on sodium dodecyl sulfate-polyacrylamide gels; these had molecular weights of 2,000 and 10,000 and activity against
Lactobacillus sake
ATCC 15521. The crude bacteriocin preparation was bacteriostatic and dissipated proton motive force. Bacteriocin activity was produced over a wide pH range (5.2 to 7.9) on buffered agar medium, with an optimum pH of pH 6.15. The optimum pH for production in broth was 6.5 to 7.0.
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Affiliation(s)
- C B Lewus
- Department of Food Science and George H. Cook Honors Program, New Jersey Agricultural Experiment Station, Cook College, Rutgers-The State University, New Brunswick, New Jersey 08903-0231
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