Concentration Of L-glutamic Acid Research Articles

Effects of Exogenous Substances Treatment on Fruit Quality and Pericarp Anthocyanin Metabolism of Peach

In this study, the two peach cultivars ‘Baifeng’ and ‘Weiduanmihong’ were used as experimental materials, and their fruits were sprayed with different concentrations of L-glutamic acid, brassinolide, and sucrose to study the effects of these three exogenous substances on fruit quality and anthocyanin metabolism of peaches. The results showed that the appearance quality (average single fruit weight, fruit firmness, and peel color difference), nutritional quality (soluble solids, soluble sugar, titratable acid, anthocyanins, total phenols, flavonoids, etc.), peel anthocyanin-related enzyme activity, and related gene expression of ‘Baifeng’ and ‘Weiduanmihong’ peaches treated with three different exogenous substances were different from those of the control. Higher-concentration treatments could significantly improve the appearance of peach fruit, the nutritional quality of peach fruit and the activity of anthocyanin-related enzymes in peel, as well as promote the expression of related genes. Treatment with 400 mg/L L-glutamic acid significantly promoted the average fruit weight of ‘Baifeng’ peaches. Treatment with 800 mg/L L-glutamic acid significantly promoted the increase in PAL enzyme activity and the expression of PpPAL and PpF3H in the two peach varieties and significantly promoted the expression of anthocyanin metabolism genes PpF3′H and PpGST1 in ‘Baifeng’ peach peel and anthocyanin metabolism gene PpUFGT in ‘Weiduanmihong’ peach peel. Treatment with 34 mg/L sucrose significantly increased the fruit firmness of ‘Baifeng’ peaches and the soluble sugar content of ‘Weiduanmihong’ peaches. Treatment with 51 mg/L sucrose significantly promoted the increase in flavonoid content and PpUFGT expression in ‘Baifeng’ peach fruit and significantly promoted the expression of anthocyanin metabolism genes PpDFR and PpANS in ‘Weiduanmihong’ peach peel. Treatment with 0.6 mg/L brassinolide significantly promoted the increase in soluble solids (TTS), soluble sugar, anthocyanin, total phenol content, PAL enzyme activity, UFGT enzyme activity, and the expression of anthocyanin metabolism genes PpDFR and PpMYB10.1 in ‘Baifeng’ peach fruit, and it significantly increased the average single fruit weight, fruit hardness, anthocyanin content, and UFGT enzyme activity of ‘Weiduanmihong’ peach fruit and promoted the expression of anthocyanin metabolism genes PpF3H and PpGST1 in ‘Weiduanmihong’ peach peel. The comprehensive effect of 0.6 mg/L brassinolide treatment on improving peach fruit quality and increasing anthocyanin content produces the best results and could be popularized in production practices.

Submerged and Solid-State Fermentation of Spirulina with Lactic Acid Bacteria Strains: Antimicrobial Properties and the Formation of Bioactive Compounds of Protein Origin.

The aim of this study was to investigate the changes in bioactive compounds (L-glutamic acid (L-Glu), gamma-aminobutyric acid (GABA) and biogenic amines (BAs)) during the submerged (SMF) and solid-state (SSF) fermentation of Spirulina with lactobacilli strains (Lacticaseibacillus paracasei No. 244; Levilactobacillus brevis No. 173; Leuconostoc mesenteroides No. 225; Liquorilactobacillus uvarum No. 245). The antimicrobial properties of the untreated and fermented Spirulina against a variety of pathogenic and opportunistic strains were tested. The highest concentrations of L-Glu (3841 mg/kg) and GABA (2396 mg/kg) were found after 48 h of SSF with No. 173 and No. 244 strains, respectively. The LAB strain used for biotreatment and the process conditions, as well as the interaction of these factors, had statistically significant effects on the GABA concentration in Spirulina (p ≤ 0.001, p = 0.019 and p = 0.011, respectively). In all cases, the SSF of Spirulina had a higher total BA content than SMF. Most of the fermented Spirulina showed exceptional antimicrobial activity against Staphylococcus aureus but not against the other pathogenic bacteria. The ratios of BA/GABA and BA/L-Glu ranged from 0.5 to 62 and from 0.31 to 10.7, respectively. The GABA content was correlated with putrescine, cadaverine, histamine, tyramine, spermidine and spermine contents. The L-glutamic acid concentration showed positive moderate correlations with tryptamine, putrescine, spermidine and spermine. To summarize, while high concentrations of desirable compounds are formed during fermentation, the formation of non-desirable compounds (BAs) must also be considered due to the similar mechanism of their synthesis as well as the possibility of obtaining high concentrations in the end products.

Multi-omic Analysis of the Gut Microbiome in Rats with Lithium-Pilocarpine-Induced Temporal Lobe Epilepsy.

Evidence supports that the gut microbiota and bacteria-dependent metabolites influence the maintenance of epileptic brain activity. However, the alterations in the gut microbiota between epileptic versus healthy individuals are poorly understood. We used a multi-omic approach to evaluate the changes in the composition of gut metagenome as well in the fecal metabolomic profile in rats before and after being submitted to status epilepticus (SE)-induced temporal lobe epilepsy (TLE). The 16S ribosomal RNA (rRNA) sequencing of fecal samples coupled to bioinformatic analysis revealed taxonomic, compositional, and functional shifts in epileptic rats. The species richness (Chao1 index) was significantly lower in the post-TLE group, and the β-diversity analysis revealed clustering separated from the pre-TLE group. The taxonomic abundance analysis showed a significant increase of phylum Desulfobacterota and a decrease of Patescibacteria in the post-TLE group. The DESEq2 and LEfSe analysis resulted in 18 genera significantly enriched between post-TLE and pre-TLE groups at the genus level. We observed that epileptic rats present a peculiar metabolic phenotype, including a lower concentration of D-glucose and L-lactic acid and a higher concentration of L-glutamic acid and glycine. The microbiota-host metabolic correlation analysis showed that the genera differentially abundant in post-TLE rats are associated with the altered metabolites, especially the proinflammatory Desulfovibrio and Marvinbryantia, which were enriched in epileptic animals and positively correlated with these excitatory neurotransmitters and carbohydrate metabolites. Therefore, our data revealed a correlation between dysbacteriosis in epileptic animals and fecal metabolites that are known to be relevant for maintaining epileptic brain activity by enhancing chronic inflammation, an excitatory-inhibitory imbalance, and/or a metabolic disturbance. These data are promising and suggest that targeting the gut microbiota could provide a novel avenue for preventing and treating acquired epilepsy. However, the causal relationship between these microbial/metabolite components and the SRS occurrence still needs further exploration.

Improved spectral model building for using ATR-FTIR spectroscopy to measure solution concentration during cooling crystallization

To ensure in-situ measurement accuracy on the solution concentration during cooling crystallization process, an improved spectral model building method is proposed in this paper for application of the attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. The traditional partial least-squares (PLS) model is modified into a functional regression form for expressing the relationship between the input variables of in-situ measured spectra and the output of solution concentration, so as to address the issue of insufficient samples for model calibration with respect to the high-dimension of spectral variables for measurement. The widely used DB4 wavelet functions are taken as basis functions to approximate the smooth functions in the proposed functional regression model, by virtue of their multi-scale and orthogonal properties to procure good accuracy. Accordingly, a parameter estimation algorithm named wavelet partial-least-squares is proposed for the spectral model calibration. The application to measure the solution concentration of L-glutamic acid (LGA) cooling crystallization process well demonstrates the effectiveness and merit of the proposed method.

High production of L-glutamic acid from date juice extracts by Corynebacterium glutamicum using fed-batch cultures: pulsed and continuous feeding modes

Abstract In the present work, L-glutamic acid production by Corynebacterium glutamicum fermentation on date juice extracts applying two fed-batch feeding modes, pulsed and continuous, were investigated. According to the obtained results, the continuous feeding fed-batch mode was found to be the most efficient process. Moreover the continuous feeding rate mode with a feeding medium containing date juice sugars enriched with ammonium sulfate was found even more favorable as it enhances the L-glutamic acid production by approximately 2.35 fold more than the batch culture and by about 1.17 fold more than the pulsed feeding. In this respect, comparing the traditional batch culture to the continuously fed culture with a medium containing date juice sugars with ammonium sulfate showed increases of 135.47% in L-glutamic acid production, 104% in productivity, 39.09% in biomass, and 47.69% in the yield respectively allowing us to reach a final L-glutamic acid concentration of about 138 g/L, the highest ever published.

An enzyme free detection of L-Glutamic acid using deposited CuO.GdO nanospikes on a flat glassy carbon electrode

Here, copper oxide doped gadolinium oxide nanospikes (CuO.GdO NSs) were prepared by hydrothermal process at low temperature in an alkaline phase. CuO.GdO NSs were characterized by conventional techniques, for example Fourier Transform Infrared Spectroscopy (FTIR), UV–visible Spectroscopy (UV–visible), powder X-ray diffraction (XRD), Field-Emission Scanning Electron Microscopy (FESEM) equipped with X-ray electron dispersive spectroscopy (XEDS), and X-ray photoelectron spectroscopy (XPS). A sensitive and selective L-Glutamic acid sensor was developed with deposition of a thin-layer of doped NSs onto a glassy carbon electrode (GCE, surface area = 0.0316 cm2) by using coating 5% Nafion binder. Enhanced electrochemical performances such as higher sensitivity, lower limit of detection, linear dynamic range, and long-term stability of fabricated L-Glutamic acid sensor were achieved by a reliable current-voltage system. Calibration curve was found linear (R2 = 0.9982) over a wide range of L-Glutamic acid concentration (100.0 pM ~100.0 mM). Based on SNR ~3, sensitivity and limit of detection of sensor were calculated as sensitivity (569.62 μAnM−1cm−2), and LOD (166.67 pM) respectively. This expected CuO.GdO NSs/Nafion/GCE sensor probe is used for the real sample analysis (Human and rabbit serum) and found acceptable results. This proposed electrochemical approach can be a pioneer sensor development in enzyme less sensor improvement for assessment of bio-molecules in health care and biomedical fields in broad scales.

L-Glutamic acid induced the colonization of high-efficiency nitrogen-fixing strain Ac63 (Azotobacter chroococcum) in roots of Amaranthus tricolor

The aim of this study was to evaluate its feasibility of a non-symbiotic nitrogen-fixing strain, Ac63 (Azotobacter chroococcum), to promote biomass of common vegetable crops and its colonization mechanisms in their roots. Root exudates of common vegetables, including Amaranthus tricolor (AT), Willow amaranth (WA), Chrysanthemum coronarium (CC), cabbage, and lettuce, were collected, and a chemotaxis assay with Ac63 was performed. Components in exudates for the most differential chemotaxis effect crops (AT and lettuce) were determined with GC-MS. Then, the traditional screening strategies of chemotaxis, swarming, and in vitro were utilized to find the signal molecule for this strain. Finally, the colonization effects of Ac63 in roots of these two crops were verified with a soil pot experiment. Chemotaxis effects of root exudates on Ac63 follow the lists of AT > WA > CC > cabbage ≈ control (water) ≈ lettuce. With a 30-μM concentration of l-glutamic acid, bacterial amount of Ac63 in chemotaxis and in vitro was observed with 2.9- and 7.4-times enhancement compared with that in the control. Laser confocal microscopy indicated that l-glutamic acid induced Ac63 to form a robust biofilm in roots, suggesting that l-glutamic acid is a signal molecule for the colonization of this strain. Soil pot assay showed that the biomass, chlorophyll, and available nitrogen of AT significantly increased than those of lettuce after Ac63 inoculation, resulting from this strain was substantially increased in roots of AT with l-glutamic acid secretion. l-Glutamic acid induced the colonization of high-efficiency nitrogen-fixing strain Ac63 in AT roots, which provides a practical information for its agricultural applications.

Factors affecting resistance of winter rapeseed (Brassica napus L.) shoots to cold stress in vitro

Research was carried out at the Institute of Biology and Plant Biotechnology of Aleksandras Stulginskis University and at the Laboratory of Agrobiotechnology of the Joint Research Centre. The effect of cultivar, acclimation duration and exogenous L-glutamic acid on the changes of proline level and electrolyte leakage in shoots of winter rapeseed was evaluated. The shoots were cultivated in the MS medium supplemented with 0, 1, 2, 3 and 4.0 mM l–1 L-glutamic acid. The resistance of shoots to cold stress (at –8 °C for 24 h) was estimated by an electrolyte leakage test. It was found that the exogenous L-glutamic acid stimulates the synthesis of endogenous proline in non-acclimated as well as acclimated shoots. The highest increasing in cold resistance of winter rapeseed shoots has been obtained under the synergic effect of L-glutamic acid and acclimation. The shoots of cultivar ‘SY Kolumb’ were most cold-resistant independent of the acclimation duration and the concentration of L-glutamic acid in the medium.

Hierarchical wheat-like Au–Pd heterostructures with enhanced catalytic activity toward methanol electrooxidation

In this report, a simple, facile, controllable, and green one-step electrochemical co-deposition method was developed for the preparation of hierarchical wheat-like Au–Pd heterostructures on a glassy carbon electrode (GCE) without any template or surfactant, only using l-glutamic acid as a growth directing agent. The control experiments associated with the applied potential, the molar ratio of HAuCl4 to PdCl2, electrodeposition time, and concentration of l-glutamic acid were investigated in details. Meanwhile, the electrochemical experiments demonstrate the superior electrocatalytic activity of the Au–Pd heterostructures toward methanol oxidation, achieving a maximum catalytic current density of 45.8mAcm−2 in the presence of 0.5M methanol, much larger than those on pure Au (5.4mAcm−2) or Pd (25.0mAcm−2) under the same conditions.

Electrosynthesis of Poly(thiophene-3-acetic Acid) Film in Ionic Liquids for Covalent Immobilization of Biologically Active Species

Poly(thiophene-3-acetic acid) (PTAA) film with good biocompatibility, low toxicity, and high conductivity was electrosynthesized in an ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate. Glutamate oxidase (GO), one of biologically active species, was covalently immobilized on the surface of PTAA film for the design and fabrication of the electrochemical biosensor. The impedance spectroscopy, infrared spectra, and scanning electron microscopy indicated that GO molecules were successfully immobilized on the surface of PTAA film. The oxidation current increased linearly with the concentration of L-glutamic acid in the range from 6 × 10−7 to 3 × 10−3 M with a regression coefficient of 0.998. The limit of detection was found to be 0. 23 µM, this method also provided a sensitivity of 87.1 mA M−1 cm−2, and a response time of less than 5 s. Moreover, the bioaffinity and operational and storage stability of the biosensor were also evaluated. Satisfactory results indicated that the resulting PTAA film is a promising candidate for the covalent immobilization of biologically active species.

The complete genome sequence of Pantoea ananatis AJ13355, an organism with great biotechnological potential

Pantoea ananatis AJ13355 is a newly identified member of the Enterobacteriaceae family with promising biotechnological applications. This bacterium is able to grow at an acidic pH and is resistant to saturating concentrations of L-glutamic acid, making this organism a suitable host for the production of L-glutamate. In the current study, the complete genomic sequence of P. ananatis AJ13355 was determined. The genome was found to consist of a single circular chromosome consisting of 4,555,536 bp [DDBJ: AP012032] and a circular plasmid, pEA320, of 321,744 bp [DDBJ: AP012033]. After automated annotation, 4,071 protein-coding sequences were identified in the P. ananatis AJ13355 genome. For 4,025 of these genes, functions were assigned based on homologies to known proteins. A high level of nucleotide sequence identity (99%) was revealed between the genome of P. ananatis AJ13355 and the previously published genome of P. ananatis LMG 20103. Short colinear regions, which are identical to DNA sequences in the Escherichia coli MG1655 chromosome, were found to be widely dispersed along the P. ananatis AJ13355 genome. Conjugal gene transfer from E. coli to P. ananatis, mediated by homologous recombination between short identical sequences, was also experimentally demonstrated. The determination of the genome sequence has paved the way for the directed metabolic engineering of P. ananatis to produce biotechnologically relevant compounds. Electronic supplementary materialThe online version of this article (doi:10.1007/s00253-011-3713-5) contains supplementary material, which is available to authorized users.

Electrochemical characterization of copper chemical mechanical polishing in l-glutamic acid–hydrogen peroxide-based slurries

The effect of l-glutamic acid as complexing agent in the presence of hydrogen peroxide as oxidizer in copper chemical mechanical polishing (CMP) slurry is investigated. In the CMP process, the work surface is moved against a pad, with slurry flowing between the surface and the pad. The polish rate was found to be stable over a wide range of hydrogen peroxide concentration. High concentration of either l-glutamic acid or hydrogen peroxide leads to a reduction in polish rate, but a high concentration of both chemicals does not reduce the polish rate. In the absence of hydrogen peroxide, the Cu polish rate was 0 for all the l-glutamic acid concentrations investigated. However, potentiodynamic polarization curves do not show any sign of passivation when l-glutamic acid was present in the solution. In situ open circuit potential measurements show that copper redox reactions as well as hydrogen peroxide redox reactions contribute in determining the electrochemical behavior. We propose that l-glutamic acid inhibits the copper dissolution by adsorption onto the metallic copper, but enhances copper dissolution by complexing copper ions. The results show that it is possible to conduct controllable copper CMP in mildly acidic slurries with hydrogen peroxide as oxidizer and l-glutamic acid as complexing agent.

Sequential injection ATR-FTIR spectroscopy for taste analysis in tomato

The potential of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) for food analysis has been demonstrated in many publications. Most applications, however, deal with the major disadvantage of extensive sample manipulation and cleaning of the ATR sampling compartment, which greatly reduces the sampling rate. To address this problem, in this paper, the potential of sequential injection analysis (SIA) in combination with ATR-FTIR has been studied for sugar and organic acid analysis of Belgian tomato samples. SIA allows automation of the sampling and measurement protocol. The SIA-ATR-FTIR system is optimized for measurement performance accuracy using a central composite design. The four important operational parameters studied are spectral resolution, number of co-added scans, flow rate, and sample temperature. A clear optimum is found for the number of scans (256 co-added scans) and resolution (16 cm −1) while sample temperature and flow rate are found not to significantly influence the measurement performance on the most important taste components in fruit. Hence, a stopped flow analysis – to save sample – at room temperature with 256 co-added scans at a resolution of 16 cm −1 is selected as optimal for tomato juice measurements. This setup results in a sample throughput of 24 samples/h. Different tomato cultivars were discriminated based on their acid and sugar content, which are the most important chemical components determining tomato taste. Prediction models for d-glucose, d-fructose, citric acid and l-glutamic acid concentrations in tomato samples were successful for the measured tomato cultivars with RMSEP-values of 1.81 g L −1, 1.63 g L −1, 0.41 g L −1 and 0.35 g L −1 respectively. However, the prediction model for l-malic acid, which is present in very small concentrations in tomato fruit, was not successful.

Central l-arginine reduced stress responses are mediated by l-ornithine in neonatal chicks

Recently, we observed that central administration of L-arginine attenuated stress responses in neonatal chicks, but the contribution of nitric oxide (NO) to this response was minimal. The sedative and hypnotic effects of L-arginine may be due to L-arginine itself and/or its metabolites, excluding NO. To clarify the mechanism, the effect of intracerebroventricular (i.c.v.) injection of L-arginine metabolites on behavior under social separation stress was investigated. The i.c.v. injection of agmatine, a guanidino metabolite of L-arginine, had no effect during a 10 min behavioral test. In contrast, the i.c.v. injection of L-ornithine clearly attenuated the stress response in a dose-dependent manner, and induced sleep-like behavior. The L-ornithine concentration in the telencephalon and diencephalon increased following the i.c.v. injection of L-arginine. In addition, several free amino acids including L-alanine, glycine, L-proline and L-glutamic acid concentrations increased in the telencephalon. In conclusion, it appears that L-ornithine, produced by arginase from L-arginine in the brain, plays an important role in the sedative and hypnotic effects of L-arginine observed during a stress response. In addition, several other amino acids having a sedative effect might partly participate in the sedative and hypnotic effects of L-arginine.

Extracellular Hypothalamic γ-Aminobutyric Acid (GABA) and L-Glutamic Acid Concentrations in Response to Bicuculline in a Genetic Absence Epilepsy Rat Model

The posterior part of the hypothalamus plays a vital role in the homeostatic processes of the internal environment, including blood pressure and heart rate regulation, by means of γ-aminobutyric acid (GABA)ergic and glutamatergic neurotransmission. In this study we measured the extracellular levels of GABA and L-glutamic acid in the dorsomedial hypothalamic nucleus (DMH) and posterior hypothalamus (PH), following intracerebroventricular (i.c.v.) administration of bicuculline, a GABAA-receptor antagonist, in genetic absence epileptic rats from Strasbourg (GAERS), where heart rate, blood pressure, and EEG recordings were also collected simultaneously. The i.c.v. injection of bicuculline (0.3 nmol) produced no response in nonepileptic Wistar rats but caused an increase in mean arterial pressure in GAERS (P <0.01). Microdialysis experiments showed that L-glutamic acid increased in the DMH in GAERS after bicuculline administration (P <0.01). Additionally, extracellular GABA concentration decreased in the PH (P <0.05). Bicuculline suppressed the spike-and-wave discharges, the characteristic sign of absence seizures. All these results suggest that the bicuculline-induced blood pressure response is accompanied by changes in L-glutamic acid levels in the DMH and GABA levels in the PH, indicating a bicuculline hypersensitivity in the DMH and PH of GAERS that may make the GAERS display an altered mode of central cardiovascular regulation. These results suggest that the circuits affected in GAERS are not only restricted to the regions responsible for seizure generation but also present in the hypothalamus.

Regulation of SULT2B1a (pregnenolone sulfotransferase) expression in rat C6 glioma cells: Relevance of AMPA receptor-mediated NO signaling

The neurosteroid pregnenolone sulfate (PREGS), which is synthesized in glial cells, plays a significant role in learning and memory performance. The aim of this study was to investigate the regulation of expression of the steroid sulfotransferase SULT2B1a, which catalyzes the conversion of pregnenolone to PREGS, using the rat C6 glioma cell line. Rat C6 glioma cells expressed the SULT2B1a isoform, which sulfonates pregnenolone, but, neither the SULT2B1b isoform, which catalyzes cholesterol, nor the prototypical steroid sulfotransferase SULT2A1 were expressed in these cells. Increasing concentrations of l-glutamic acid in the presence of cyclothiazide, which prevents AMPA receptor desensitization, attenuated SULT2B1a mRNA expression; however, neither NMDA nor kainic acid had a significant effect. Exposure to the synthetic glutamate analogue alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) in the presence of cyclothiazide also inhibited SULT2B1a expression. Attenuation of SULT2B1a expression by L-glutamic acid was reversed by the selective AMPA/kainate receptor antagonist 2,3-dioxo-6-nitro-7-sulfamoylbenzo(f)quinoxaline (NBQX), and partially reversed by the specific neuronal nitric oxide synthase (NOS) inhibitor 7-nitroindazole (7-NI). Induction of inducible NOS by TNF-alpha in combination with lipopolysaccharide (LPS) dramatically attenuated SULT2B1a expression; this was partially reversed by the specific inducible NOS inhibitor N(6)-(1-iminoethyl)-L-lysine hydrochloride (L-NIL). Furthermore, exposure to exogenous NO donors inhibited SULT2B1a mRNA expression, and exposure to sodium nitroprusside, LPS/TNF-alpha and L-glutamic acid in combination with cyclothiazide increased the production of nitrite, a stable degradation product of NO. These findings suggest that expression of SULT2B1a, which catalyzes PREGS production, is inhibited by activation of excitatory amino acid receptors of the AMPA subtype, via facilitation of intracellular NO signaling.

Ácido L-glutâmico na prevenção da calcificação de pericárdio bovino fixado em glutaraldeído: estudo em ratos

To evaluate the efficiency of L-glutamic acid to prevent calcification of glutaraldehyde bovine pericardium implanted in rats' subcutaneous tissues. Fifty four Wistar rats were divided in six groups according to the type of the bovine pericardium implanted. At first, all pericardia were initially cross-linked with 0.5% glutaraldehyd (GDA) fixative for 72 h. In Group I, after the initial fixation, the pericardia were preserved in 0.2% GDA fixative until the implantation, whereas in Group II they were stocked in Paraben solution. In Groups III and IV, after the initial fixation in 0.5% GDA fixative, the pericardia were treated with 8% L-glutamic acid at pH 7.4 and 3.5, respectively, being subsequently stocked in Paraben solution. Groups V and VI were similar to III and IV, except for the concentration of L-Glutamic acid which was 0.8%. Explantation was done at 15, 30, and 60 days, and the specimens submitted to histological analysis with Hematoxylin and eosin (HE) and Von Kossa stains, besides calcium quantification with atomic spectrofotometry. Microscopic analysis demonstrated severe and progressive calcification in groups I, II, and III, whereas in groups IV, V, and VI calcification, when present, was mild and focal. Spectrofotomety confirmed these findings, revealing calcium contents of 1.93 microg/mg of tissue at 60 days in the control group. Groups IV and VI showed the least calcium contents (0.063 e 0.066, respectively). The use of L-glutamic acid in segments of bovine pericardium with glutaraldehyde fixative was effective in preventing the calcification when implanted in rats' subcutaneous up to 60 days.

The effect of extractants on degradation of L-glutamate and L-arginine in the course of shaking and filtration at low temperature

The effects of demineralized water (DEMI H(2)O) and 0.5 M ammonium acetate (0.5 M AAc) on losses of L-glutamic acid and L-arginine in the course of shaking and filtration at low temperature (6 degrees C) were tested. The concentration of L-glutamic acid decreased by 6.3% in DEMI H(2)O and by 4.9% in 0.5 M AAc, whereas the L-arginine concentration decreased by 6.0% (DEMI H(2)O) and 10.7% (0.5 M AAc). We found a significantly (P < 0.05) higher degradation of L-arginine in 0.5 M AAc compared with that of DEMI H(2)O.

A study into the role of L-aspartic acid on the metabolism of L-malic acid and D-glucose by Oenococcus oeni.

The purpose of this work was to study the effect of L-aspartic acid concentration on bacterial growth, D-glucose fermentation and L-malic acid consumption of Oenococcus oeni NCFB 1707. Bacterial cultures were performed in synthetic media. Bacterial growth, D-glucose fermentation and L-malic acid consumption were reduced when L-aspartic acid concentration became excessive. This inhibitory effect of high concentrations of L-aspartic acid on bacterial growth was also observed with several Oenococcus oeni strains, except O. oeni BL01. The L-aspartic acid inhibitory effect on bacterial growth could be reduced by increasing the concentration of L-glutamic acid. L-glutamic acid transport was found to be competitively inhibited by L-aspartic acid. In addition, an excessive amount of L-aspartic acid modified D-glucose metabolism, with an overproduction of acetic acid and reduced ethanol production. Since L-glutamic acid is an essential amino acid for the bacterial strain used, the L-aspartic acid inhibitory effect on bacterial growth could be linked to its involvement in an antagonistic interaction with L-glutamic acid. Such antagonistic interactions between amino acids in O. oeni strains could be another explanation for the difficulties of inducing malolactic fermentation in wines.

Simultaneous Determination of D-Lactic Acid and L-Lactic Acid Using a Flow System With Two Enzyme Reactors and an Octadecylsilica Column in One Line

ABSTRACT Simultaneous determination of D- and L-lactic acids was achieved using an apparatus containing two enzyme reactors and an octadecylsilica column placed between the two reactors in tandem in a single flow line. The enzymes used for the D-lactic acid assay were D-lactate dehydrogenase and glutamic-pyruvic transaminase, and for the L-lactic acid assay, L-lactate dehydrogenase and glutamic-pyruvic transaminase. The optimal concentrations of L-glutamic acid and NAD+ in the carrier were determined. Of the buffers examined for use as a carrier medium, Tris buffer was found to be the most favorable. Under these optimal conditions, NADH due to D-lactic acid and that due to L-lactic acid could be observed separately in this apparatus. The calibration curve for D-lactic acid was linear in the range of 20 – 1000 μM, and that for L-lactic acid was 2 – 250 μM. This method was applied to analyze D- and L-lactic acids in several beverages that contained lactic acid bacteria. The D- and L-lactic acid content determined by the present method agreed with that determined by a commercially available test-kit method.