Loading of Cells with Fluorescent Probe to Study Intracellular Acid-base Homeostasis in Lactic Acid Bacteria

Here we describe a protocol which we have used to study the homeostasis intracellular in vivo in lactic acid bacteria (LAB) using a fluorescent probe. This type of probes can be used for determining changes in the pH of cytoplasm with high sensitivity, temporal resolution and technical simplicity as well as accessing the rate of change of intracellular pH in response to a stimulus from kinetic measurements on short time scales (Breeuwer et al., 1996; Molenaar et al., 1991). This protocol has been designed to measure the intracellular pH using the pH-sensitive fluorescent probe 2´,7´-bis-(2-carboxyethyl)-5(and-6)-carboxyfluorescein (BCECF) in LAB, Enterococcus faecalis (E. faecalis), Lactococcus lactis (L. lactis) and Lactobacillus casei (L. casei)Fil: Mortera, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Química Rosario; ArgentinaFil: Zuljan, Federico Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Química Rosario; ArgentinaFil: Magni, Christian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Alarcon, Sergio Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Química Rosario; Argentin

Multivariate analysis of organic acids in fermented food from reversed-phase high-performance liquid chromatography data

Multivariate calibration coupled to RP-HPLC with diode array detection (HPLC-DAD) was applied to the identification and the quantitative evaluation of the short chain organic acids (malic, oxalic, formic, lactic, acetic, citric, pyruvic, succinic, tartaric, propionic and α-cetoglutaric) in fermented food. The goal of the present study was to get the successful resolution of a system in the combined occurrence of strongly coeluting peaks, of distortions in the time sensors among chromatograms, and of the presence of unexpected compounds not included in the calibration step. Second-order HPLC-DAD data matrices were obtained in a short time (10 min) on a C18 column with a chromatographic system operating in isocratic mode (mobile phase was 20 mmol L−1 phosphate buffer at pH 2.20) and a flow-rate of 1.0 mL min−1 at room temperature. Parallel factor analysis (PARAFAC) and unfolded partial least-squares combined with residual bilinearization (U-PLS/RBL) were the second-order calibration algorithms select for data processing. The performance of the analytical parameters was good with an outstanding limit of detection (LODs) for acids ranging from 0.15 to 10.0 mmol L−1 in the validation samples. The improved method was applied to the analysis of many dairy products (yoghurt, cultured milk and cheese) and wine. The method was shown as an effective means for determining and following acid contents in fermented food and was characterized by reducibility with simple, high resolution and rapid procedure without derivatization of analytes.Fil: Mortera, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Zuljan, Federico Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Magni, Christian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Bortolato, Santiago Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Alarcon, Sergio Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; Argentin

Identification of malic and soluble oxaloacetate decarboxylase enzymes in Enterococcus faecalis

Two paralogous genes, maeE and citM, that encode putative malic enzyme family members were identified in the Enterococcus faecalis genome. MaeE (41 kDa) and CitM (42 kDa) share a high degree of homology between them (47% identities and 68% conservative substitutions). However, the genetic context of each gene suggested that maeE is associated with malate utilization whereas citM is linked to the citrate fermentation pathway. In the present work, we focus on the biochemical characterization and physiological contribution of these enzymes in E. faecalis. With this aim, the recombinant versions of the two proteins were expressed in Escherichia coli, affinity purified and finally their kinetic parameters were determined. This approach allowed us to establish that MaeE is a malate oxidative decarboxylating enzyme and CitM is a soluble oxaloacetate decarboxylase. Moreover, our genetic studies in E. faecalis showed that the citrate fermentation phenotype is not affected by citM deletion. On the other hand, maeE gene disruption resulted in a malate fermentation deficient strain indicating that MaeE is responsible for malate metabolism in E. faecalis. Lastly, it was demonstrated that malate fermentation in E. faecalis is associated with cytoplasmic and extracellular alkalinization which clearly contributes to pH homeostasis in neutral or mild acidic conditions. In the present study, we performed a biochemical characterization of two members of the malic enzyme family from Enterococcus faecalis. It was stated that MaeE is a malate oxidative decarboxylating enzyme whereas CitM is a soluble oxaloacetate decarboxylase. Our genetic studies showed that the citrate fermentation phenotype is not affected by citM deletion. Conversely, maeE gene disruption resulted in a malate deficient strain.Fil: Espariz, Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Repizo, Guillermo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Blancato, Victor Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Mortera, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Alarcon, Sergio Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Magni, Christian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; Argentin

Lactic acid bacteria decarboxylation reactions in cheese

Fermentation in cheese comprises oxidation-reduction of carbohydrates to yield organic acids, alcohols and carbon dioxide. Furthermore, organic acid and amino acid metabolism produces a series of compounds that positively or negatively affect final cheese quality. Under the strong selective pressure of the acidic environment of cheese ripening, lactic acid bacteria have developed multiple stress-resistant strategies, including decarboxylase and deiminase reactions that play a main physiological role during the ripening process of cheese production. The control of the expression and activity of these enzymes is one active strategy for intracellular acid-base homeostasis. This review covers relevant pathways and aspects related to gene regulation of gene clusters present in starter or non-starter lactic acid bacteria that are involved in sensory changes such as flavour development. From the point of view of food safety the main decarboxylation pathways that lead to the formation of biogenic amines are described.Fil: Zuljan, Federico Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; ArgentinaFil: Mortera, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; ArgentinaFil: Alarcon, Sergio Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; ArgentinaFil: Blancato, Victor Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; ArgentinaFil: Espariz, Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; ArgentinaFil: Magni, Christian. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; Argentin

Genomic analysis revealed conserved acid tolerance mechanisms from native micro‐organisms in fermented feed

Aims: Fermented feed is an agricultural practice used in many regions of the world to improve the growth performance of farm animals. This study aimed to identify and evaluate the lactic acid bacteria and yeast involved in the production of fermented feed. Methods and Results: We isolated and described two micro-organisms from autochthonous microbiota origin present in a regional feed product, Lactobacillus paracasei IBR07 (Lacticaseibacillus paracasei) and Kazachstania unispora IBR014 (Saccharomyces unisporum). Genome sequence analyses were performed to characterize both micro-organisms. Potential pathways involved in the acid response, tolerance and persistence were predicted in both genomes. Although L. paracasei and K. unispora are considered safe for animal feed, we analysed the presence of virulence factors, antibiotic resistance and pathogenicity islands. Furthermore, the Galleria mellonella model was used to support the safety of both isolates. Conclusions: We conclude that IBR07 and IBR014 strains are good candidates to be used as starter cultures for feed fermentation. Significance and Impact of the Study: The data presented here will be helpful to explore other biotechnological aspects and constitute a starting point for further studies to establish the consumption benefit of fermented feed in farm animal production.Fil: Teran, Lucrecia Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Mortera, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Tubio, Gisela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Procesos Biotecnológicos y Químicos Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Procesos Biotecnológicos y Químicos Rosario; ArgentinaFil: Alarcon, Sergio Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Blancato, Victor Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Espariz, Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Esteban, Luis. Universidad Nacional de Rosario. Facultad de Ciencias Médicas; ArgentinaFil: Magni, Christian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; Argentin

Novel glutamate dehydrogenase genes show increased transcript and protein abundances in mature tomato fruits

NAD(P)H-glutamate dehydrogenase (GDH, EC 1.4.1.3) contributes to the control of glutamate homeostasis in all living organisms. In bacteria and animals, GDH is a homohexamer allosterically regulated, whereas in plants NADH-GDH (EC 1.4.1.2) is also found as heterohexamer of α- and β-subunits, but its regulation remains undefined. In tomato (Solanum lycopersicum), GDH activity increases during the fruit ripening along with the content of free glutamate, the most abundant amino acid of ripe fruit involved in conferring the genuine tomato flavour. In this work, novel Slgdh-NAD genes were identified in the recently deciphered tomato genome: three encoding the α-subunit (Slgdh-NAD; A1-3) and one additional gene encoding the β-subunit of GDH (Slgdh-NAD; B1) isolated from a genomic library. These genes are located in different chromosomes. Slgdh-NAD;A1-3 show conserved structures, whereas Slgdh-NAD;B1 includes a novel 5'-untranslated exon. Slgdh-NAD;A1-3 transcripts were detected in all tomato tissues examined, showing the highest levels in mature green fruits, contrasting with Slgdh-NAD;B1 transcripts which were detected mainly in roots or in mature fruits when treated with glutamate, NaCl or salicylic acid. Analyses of GDH activity and protein distribution in different tissues of the Micro-Tom cultivar showed that only the active homohexamer of GDH β-subunits was detected in roots while heterohexamers of GDH α- and β-subunits were found in fruits. These results indicate that GDH β-subunit could modulate the heteromeric isoforms of GDH in response to the environment and physiology of the tomato fruit. This information is relevant to manipulate glutamate contents in tomato fruits genetically. © 2012 Elsevier GmbH.Fil: Ferraro, Gisela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Bortolotti, Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Mortera, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Schlereth, Armin. Max-Planck Institute of Molecular Plant Physiology; AlemaniaFil: Stitt, Mark. Max-Planck Institute of Molecular Plant Physiology; AlemaniaFil: Carrari, Fernando Oscar. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Biotecnología; ArgentinaFil: Kamenetzky, Laura. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Biotecnología; ArgentinaFil: Valle, Estela Marta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; Argentin

Ca2+-Citrate Uptake and Metabolism in Lactobacillus casei ATCC 334

<p>The putative citrate metabolic pathway in Lactobacillus casei ATCC 334 consists of the transporter CitH, a proton symporter of the citrate-divalent metal ion family of transporters CitMHS, citrate lyase, and the membrane-bound oxaloacetate decarboxylase complex OAD-ABDH. Resting cells of Lactobacillus casei ATCC 334 metabolized citrate in complex with Ca2+ and not as free citrate or the Mg2+-citrate complex, thereby identifying Ca2+-citrate as the substrate of the transporter CitH. The pathway was induced in the presence of Ca2+ and citrate during growth and repressed by the presence of glucose and of galactose, most likely by a carbon catabolite repression mechanism. The end products of Ca2+-citrate metabolism by resting cells of Lb. casei were pyruvate, acetate, and acetoin, demonstrating the activity of the membrane-bound oxaloacetate decarboxylase complex OAD-ABDH. Following pyruvate, the pathway splits into two branches. One branch is the classical citrate fermentation pathway producing acetoin by alpha-acetolactate synthase and alpha-acetolactate decarboxylase. The other branch yields acetate, for which the route is still obscure. Ca2+-citrate metabolism in a modified MRS medium lacking a carbohydrate did not significantly affect the growth characteristics, and generation of metabolic energy in the form of proton motive force (PMF) was not observed in resting cells. In contrast, carbohydrate/Ca2+-citrate cometabolism resulted in a higher biomass yield in batch culture. However, also with these cells, no generation of PMF was associated with Ca2+-citrate metabolism. It is concluded that citrate metabolism in Lb. casei is beneficial when it counteracts acidification by carbohydrate metabolism in later growth stages.</p>