Showing papers on "Citric acid published in 1998"
TL;DR: In this article, the utilization of glucose and citrate either with or without being mixed with one of four commonlyoccurring soil mineral phases was assessed using both bacterial cultures and soil incubations.
Abstract: The utilization of glucose and citrate either with or without being mixed with one of four commonly-occurring soil mineral phases was assessed using both bacterial cultures and soil incubations. Citrate and glucose, both 14 C-labelled, were added separately to bacterial cultures. In each case they were rapidly degraded with >60% recovered as CO 2 . In the presence of soil the respired proportion declined especially for glucose. The presence of mineral phases (illite–mica, kaolinite, mixed soil clay or ferric hydroxide) had little observable affect on the utilization of glucose in either bacterial cultures or soil. However, ferric hydroxide did induce an alteration in the way 14 C was partitioned within the microbial cells. In contrast, citrate degradation was greatly reduced over short periods (6–22 h) in the presence of the three clay materials and almost completely inhibited by the presence of ferric hydroxide. The importance of substrate sorption in the context of carbon utilization in the rhizosphere is discussed.
290 citations
TL;DR: In this article, the authors examined the effect of ascorbic acid and citric acid on the stability of green tea catechins (GTCs) incubated in sodium phosphate buffer (pH = 7.42).
Abstract: Green tea catechins (GTCs) as a mixture of (−)-epicatechin (EC), (−)-epicatechin gallate (ECG), (−)-epigallocatechin (EGC), and (−)-epigallocatechin gallate (EGCG) possess a variety of biological activities. We have previously studied the stability of GTCs either as a mixture or as individual epicatechin derivatives in various pH, demonstrating that GTCs as a mixture in alkaline solutions were extremely unstable and degraded almost completely in a few minutes, whereas in acidic solutions (pH < 4) they were very stable. For the pH ranging from 4 to 7, the stability of GTCs was inversely associated with the pH value of the incubation solutions. The present study examined the effect of ascorbic acid and citric acid on the stability of GTCs incubated in sodium phosphate buffer (pH = 7.42). Ascorbic acid added to the incubation mixture significantly increased the stability of GTCs whereas citric acid exhibited no effect. Four epicatechin derivatives examined demonstrated varying stability, with EGCG and EGC be...
191 citations
TL;DR: In this article, weak organic acids and their salts were tested for the remediation of a loam and a sandy clay loam naturally polluted by heavy metals for over three years against two strong synthetic chelating agents (EDTA and DTPA).
Abstract: Various weak organic acids and/or their salts were tested for the remediation of a loam and a sandy clay loam naturally polluted by heavy metals for over three years against two strong synthetic chelating agents (EDTA and DTPA). Among 7 weak organic acids and/or their salts, citrate, tartarate and oxalate were found to effectively remove Cd, Cu, Pb and Zn from the two soils in double extractions, at a wide range of pH. Citrate removed 80 to 99.9% of all four metals within 24 h at pH from 2.3 to 7.5. Tartarate removed 84 to 99.9% of all metals from both soils within 24 h at pH from 2.1 to 6.7. Oxalate alone is not effective in removing metals particularly Pb but with ammonium citrate (1:1 ratio) removed effectively 82, 70, 99.9, and 99.9% for Cd, Pb, Cu and Zn, respectively at pH from 2.6 to 5.8. Zinc met the Quebec A level soil clean-up criteria after two extractions whereas Cu and Pb reached the B level. Probably, two more extractions with these weak organic acids and/or their salts are required to meet ...
168 citations
TL;DR: Two components of an amorphous solid mixture containing citric acid and indomethacin with limited solid state miscibility can be solublized as an amomorphous solid phase by the addition of moderate levels of PVP.
Abstract: Purpose To better understand the nature of drug-excipient interactions we have studied the phase behavior of amorphous binary and ternary mixtures of citric acid, indomethacin and PVP, as model systems
154 citations
TL;DR: The additions of citric acid and phytase to weanling pig diets were each beneficial, but no synergistic effects were observed.
Abstract: Crossbred weanling pigs (an equal number of barrows and gilts) with an average initial weight of 7.4 (Exp. 1) or 9.6 kg (Exp. 2) were used in two 4-wk experiments (Exp. 1, n = 96; Exp. 2, n = 96) to investigate the effects of added phytase or citric acid on performance, rib mineralization, gastric pH, and digestibility measurements. A corn-soybean meal-based diet low in Ca and P was used in both experiments. In Exp. 1, three citric acid levels (0, 1.5, or 3.0%) and four phytase levels (0, 250, 500, or 750 U/kg) were used in a 3 x 4 factorial arrangement of treatments. In Exp. 2, two citric acid levels (0 or 2.0%) and three phytase levels (0, 250, or 500 U/kg) were used in a 2 x 3 factorial arrangement of treatments. Phosphorus was maintained at .33 and .34% in Exp. 1 and 2, respectively. Calcium was maintained at a 2.5:1 ratio with total available P (available P plus the estimated released phytate P by phytase) in Exp. 1 and at a level of .44% in Exp. 2. In both experiments, BW and feed consumption were measured weekly, and pen fecal samples were collected twice daily for 5 d during wk 4. At the end of wk 4, the barrow in each pen was killed following a fast-refeed-fast (22-1-2 h) regimen for collection of 10th ribs and stomach digesta. In Exp. 1 and 2, phytase addition did not affect (P > .05) performance but linearly increased (P < .05) rib shear force, shear energy, dry bone weight, ash weight, ash percentage, and Ca and P digestibilities. Addition of citric acid in both experiments reduced dietary pH and stomach digesta pH (P < .05). The addition of citric acid improved (P < .05) ADG, feed efficiency, and Ca digestibility in Exp. 1, but it had no effect on performance and Ca digestibility in Exp. 2. In summary, the additions of citric acid and phytase to weanling pig diets were each beneficial, but no synergistic effects were observed.
144 citations
TL;DR: Apparent availabilities of calcium and phosphorus were greatly affected by citric acid supplementation in rainbow trout but not in goldfish; however, this level of dietary acidification had little effect on the apparent availability of major minerals in fish meal-based diet.
134 citations
TL;DR: It is suggested that the E. coli CitT protein is a member of a novel family of eubacterial transporters involved in the transport of di- and tricarboxylic acids.
Abstract: Under anoxic conditions in the presence of an oxidizable cosubstrate such as glucose or glycerol, Escherichia coli converts citrate to acetate and succinate Two enzymes are specifically required for the fermentation of the tricarboxylic acid, ie, a citrate uptake system and citrate lyase Here we report that the open reading frame (designated citT) located at 1390 min on the E coli chromosome between rna and the citrate lyase genes encodes a citrate carrier E coli transformed with a plasmid expressing citT was capable of aerobic growth on citrate, which provides convincing evidence for a function of CitT as a citrate carrier Transport studies with cell suspensions of the transformed strain indicated that CitT catalyzes a homologous exchange of citrate or a heterologous exchange against succinate, fumarate, or tartrate Since succinate is the end product of citrate fermentation in E coli, it is likely that CitT functions in vivo as a citrate/succinate antiporter Analysis of the primary sequence showed that CitT (487 amino acids, 531 kDa) is a highly hydrophobic protein with 12 putative transmembrane helices Sequence comparisons revealed that CitT is related to the 2-oxoglutarate/malate translocator (SODiT1 gene product) from spinach chloroplasts and five bacterial gene products, none of which has yet been functionally characterized It is suggested that the E coli CitT protein is a member of a novel family of eubacterial transporters involved in the transport of di- and tricarboxylic acids
130 citations
TL;DR: Citric acid (cA) and chitosan are used as durable press and antimicrobial finishing agents for cotton, and are applied by means of the conventional pad-dry-cure process.
Abstract: Citric acid (cA) and chitosan are used as durable press and antimicrobial finishing agents for cotton, and are applied by means of the conventional pad-dry-cure process. CA is expected to react wit...
129 citations
04 Aug 1998
TL;DR: Of all the treatments studied, germination appears to be the best processing method to obtain nutritive faba bean flour, since it caused a minor decrease in starch content, the largest α-galactoside and phytic acid removal and provided an appreciable amount of dietary fibre.
Abstract: The influence on the nutrients content (soluble sugars, starch, dietary fibre and calcium) and antinutritional factors (α-galactosides and phytic acid) of faba beans (Vicia faba, L. major) of soaking in different solutions (distilled water, citric acid, and sodium bicarbonate solutions), cooking the presoaked seeds, dry-heating and germination have been studied. Soaking brought about a decrease in starch, sucrose, fructose, α-galactoside, dietary fibre and calcium content. Glucose was detected in soaked faba beans and soaking did not modify the phytic acid content. Cooking the presoaked faba beans produced a slight decrease in starch, and caused a general drop in α-galactosides, dietary fibre, calcium and phytic acid, with the exception of seeds presoaked in sodium bicarbonate in which cooking did not cause any appreciable changes in comparison with the unprocessed faba beans. Germination caused a sharp reduction in α-galactoside and phytic acid content after 6 days, whilst starch and dietary fibre decreased slightly. Calcium, however, enjoyed a slight increment during germination which was related to the decrease in the content of hemicellulose and phytic acid. Dry-heating caused a noticeable reduction in all the nutrients and antinutritional factors investigated. Of all the treatments studied, germination appears to be the best processing method to obtain nutritive faba bean flour, since it caused a minor decrease in starch content (15% loss), the largest α-galactoside and phytic acid removal (94% and 45%, respectively) and provided an appreciable amount of dietary fibre.
116 citations
TL;DR: The effect of foliar silicon (Si) applications on metabolic changes in strawberry plants (Fragaria x ananassa Duch) was studied in this article, where Silicon was used in the form of the potassium (K) salt.
Abstract: The effect of foliar silicon (Si) applications on metabolic changes in strawberry plants (Fragaria x ananassa Duch.) was studied. Silicon was used in the form of the potassium (K) salt. Foliar spray with K silicate (containing 0, 4.25, 8.50, 12.75, or 17.00 mm of Si) showed increased chlorophyll content and plant growth. Potassium silicate treatments also induced metabolic changes such as increases in citric acid and malic acid levels, and decreases in fructose, glucose, sucrose, and myo‐inositol contents. The treated tissues also had higher ratios of fatty acid unsaturation [(18:2+18:3)/18:1] in glycolipids and phospholipid and elevated amounts of membrane lipids. These results suggest that Si has beneficial effects on strawberry plant metabolism.
112 citations
TL;DR: In this paper, the use of 10 mmol litre −1 glutathione and 100 mmollitre − 1 citric acid was found to give good control of the browning of litchi fruit and 80-85% inhibition of PPO observed.
TL;DR: The oxygen transfer coefficient increases with the agitation rate and the oxygen consumption rate increased almost linearly with the biomass concentration; however, substrate consumption was highest at HOT conditions.
TL;DR: This study demonstrates for the first time that astringency elicited by acids is a function of pH and not concentration or anion species, and confirms that sourness is independently influenced by concentration, pH and anions species of the acid.
Abstract: The separate effects of concentration, pH and anion species on intensity of sourness and astringency of organic acids were evaluated. Judges rated sourness and astringency intensity of lactic, malic, tartaric and citric acid solutions at three levels of constant pH varying in normality and at three levels of constant concentration varying in pH. To assess the comparative sourness and astringency of the organic acid anions of study, binary acid solutions matched in pH and titratable acidity were also rated. As pH was decreased in equinormal solutions, both sourness and astringency in- creased significantly (P < 0.001). By contrast, as the normality of the equi-pH solutions was increased, only sourness demonstrated significant increases (P < 0.001) while astringency remained constant or decreased slightly. At the lowest normality tested, all solutions were more astringent than sour (P < 0.05). Although lactic acid was found to be significantly more sour than citric acid (P < 0.05), no other sourness or astringency differences among the organic acid anions were noted. This study demonstrates for the first time that astringency elicited by acids is a function of pH and not concentration or anion species, and confirms that sourness is independently influenced by concentration, pH and anion species of the acid.
TL;DR: It is suggested that alum cannot be used interchangeably with phenolic astringents in psychophysical studies because of the difference in astringency between alum and the phenolic compounds.
Abstract: Astringency of aqueous solutions of phenolic compounds (grape seed tannins, tannic acid, catechin and gallic acid) increased upon addition of citric acid, whereas the astringency of alum was reduced. Astringency of alum was decreased equivalently by addition of equi-sour levels of lactic acid, citric acid or hydrochloric acid. The difference between alum and the phenolic compounds is speculated to result from chemical modifications affecting binding of the astringents with oral proteins rather than cognitive differences. Chelation of the aluminum ion in alum by acids reduces its availability for interacting with salivary proteins or epithelial proteins. In contrast, the increased astringency produced upon acidification of phenolic compounds is speculated to result from the pH driven increase in the affinity of the phenols for binding with proteins. These results suggest that alum cannot be used interchangeably with phenolic astringents in psychophysical studies.
TL;DR: This acid stress response seems to provide L. lactis biovar diacetylactis with a selective advantage resulting from cometabolism of glucose and citrate at low pHs.
Abstract: Citrate transport in Lactococcus lactis subsp. lactis biovar diacetylactis is catalyzed by citrate permease P (CitP), which is encoded by the plasmidic citP gene. We have shown previously that citP is included in the citQRP operon, which is mainly transcribed from the P1 promoter in L. lactis subsp. lactis biovar diacetylactis. Furthermore, transcription of citQRP and citrate transport are not induced by the presence of citrate in the growth medium. In this work, we analyzed the influence of the extracellular pH on the expression of citP. The citrate transport system is induced by natural acidification of the medium during cell growth and by a shift to media buffered at acidic pHs. This inducible response to acid stress takes place at the transcriptional level and seems to be due to increased utilization of the P1 promoter. Increased transcription correlates with increased synthesis of CitP and results in higher citrate transport activity catalyzed by the cells. Finally, this acid stress response seems to provide L. lactis subsp. lactis biovar diacetylactis with a selective advantage resulting from cometabolism of glucose and citrate at low pHs.
TL;DR: It is suggested that ligands with high affinity for Fe (e.g. EDTA) can prevent Fe from binding tannin and can remove Fe already bound.
TL;DR: Although the survival of E. coli O157:H7 in refrigerated acidic beverages may not be affected by the type of acidifier used, the subsequent survival in SGF of this pathogen may be critically dependent on this factor.
TL;DR: In this article, a silt loam soil spiked with lead (ca. 1000 mg/kg) was treated by electrokinetics using an electric gradient of 1 V/cm, and 0.1 M acetic acid was used as the cathode reservoir fluid.
TL;DR: A series of experiments was conducted to quantify the relative contribution of protons and other mechanisms to the dissolution of phosphate rocks (PRs) from six countries in solutions of low-molecular-weight aliphatic organic acids as mentioned in this paper.
Abstract: A series of experiments was conducted to quantify the relative contribution of protons and other mechanisms to the dissolution of phosphate rocks (PRs) from six countries in solutions of low-molecular-weight-aliphatic organic acids. The amounts of P and Ca released after 3 d of incubation at 28°C were determined in all the experiments. In the first experiment the solubility of the PRs < 500 μm particle size) in 100 M (25 mL g-1 PR) oxalic, tartaric, and citric acids was compared with that in three mineral acids and four chelating compounds. There were no differences in the amount of P released by the mineral acids, but the organic acids released more P than could be accounted for by protonation. The chelating compounds were the least effective. In the second experiment, 1 g each of Sri Lanka and Togo PRs was incubated with 2.5 mmol of the organic acids using three acid concentration (mM) : acid volume ratios (250:10, 100:25, and 25:100). The amount of P dissolved from the PRs and the amount of ac...
TL;DR: Citric acid production was best in flasks, with lower yields being obtained in tray and rotating drum bioreactors, and Aspergillus niger produced the highest amount of citric acid.
Abstract: Aspergillus foetidus ACR I 3996 (=FRR 3558) and three strains of Aspergillus niger ACM 4992 (=ATCC 9142), ACM 4993 (=ATCC 10577), ACM 4994 (=ATCC 12846) were compared for the production of citric acid from pineapple peel in solid-state fermentation. A. niger ACM 4992 produced the highest amount of citric acid, with a yield of 19.4 g of citric acid per 100 g of dry fermented pineapple waste under optimum conditions, representing a yield of 0.74 g citric acid/g sugar consumed. Optimal conditions were 65% (w/w) initial moisture content, 3% (v/w) methanol, 30 degrees C, an unadjusted initial pH of 3.4, a particle size of 2 mm and 5 ppm Fe2+. Citric acid production was best in flasks, with lower yields being obtained in tray and rotating drum bioreactors.
TL;DR: In this paper, a pseudo-cubic BaSnO 3 with lattice parameter a 0 = 0.4118±0.0003nm was identified as a barium-tin precursor.
TL;DR: In this article, Aspergillus niger was found to produce the highest amount of citric acid (250 g/kg dry matter of corncobs) after 72 h of growth at 30°C in the presence of 3% methanol.
TL;DR: In this paper, the quality of a new variety of apple, "Jonagored", after peeling and cutting was evaluated during ten days of storage in air at 4C, and the objective was to evaluate the shelf-life of apple cubes by detecting the limiting parameter and to test the influence of different chemical dips on the cut apple quality with the aim of extending shelf life.
Abstract: The quality of a new variety of apple, 'Jonagored', after peeling and cutting was evaluated during ten days of storage in air at 4C. The objective was to evaluate the shelf-life of apple cubes by detecting the limiting parameter and to test the influence of different chemical dips on the cut apple quality with the aim of extending shelf-life. Color, i. e. browning at the cut surface, was found to be the critical quality parameter determining the shelf-life of the cut apple to less than three days. There were no significant differences between the dip treatments in measurements of CIE values. When apple cubes were treated with ascorbic acid, ascorbic acid plus calcium chloride or ascorbic acid plus calcium chloride and citric acid, the 0.75% ascorbic acid dip was found to be the most effective preservation treatment in terms of reducing color change of the cut surface. Both 0.75% ascorbic acid and 0.75% ascorbic acid plus 0.75% calcium chloride inhibited the loss of firmness of apple cubes. When citric acid was added to the dip treatment, there were color changes similar to those of the control.
Patent•
01 Sep 1998
TL;DR: In this paper, a pharmaceutical composition which includes a sugar and a Krebs cycle intermediate, or salt thereof, or a precursor of a k-cycle intermediate is described, and the present invention relates to administration of the pharmaceutical composition to treat an individual for a disorder involving impaired mitochondrial function.
Abstract: The present invention relates to a pharmaceutical composition which includes a sugar and a Krebs cycle intermediate, or salt thereof, or a precursor of a Krebs cycle intermediate. Krebs cycle intermediates include citric acid, aconitic acid, isocitric acid, α-ketoglutaric, succinic acid, fumaric acid, malic acid, and oxaloacetic acid, and mixtures thereof. Precursors of Krebs cycle intermediates are compounds converted by the body to form a Krebs cycle intermediate. The present invention also relates to administration of the pharmaceutical composition to treat an individual for a disorder involving impaired mitochondrial function and to improve cerebral function in an individual having impaired cerebral metabolism.
TL;DR: In this article, a review of the new developments of recovery of citric acid from the fermentation broth is presented, focusing on the new development of extraction and extraction of the acid from fermentation broth.
Abstract: The requirement of citric acid is increasing every year. Therefore, it is important to have an efficient recovery method following the production of citric acid. At present, most of the manufacturers use the classical method of citric acid recovery which is a precipitation technique using calcium salt followed by filtration and subsequently treated with sulphuric acid. This review focuses on the new developments of recovery of citric acid from the fermentation broth.
TL;DR: It is demonstrated that the endogenous CitP of Lactococcus lactis has the same properties, showing that the few differences in the amino acid sequences of the CitPs of members of the two genera do not result in different catalytic mechanisms.
Abstract: Citrate metabolism in the lactic acid bacterium Leuconostoc mesenteroides generates an electrochemical proton gradient across the membrane by a secondary mechanism (C. Marty-Teysset, C. Posthuma, J. S. Lolkema, P. Schmitt, C. Divies, and W. N. Konings, J. Bacteriol. 178:2178–2185, 1996). Reports on the energetics of citrate metabolism in the related organism Lactococcus lactis are contradictory, and this study was performed to clarify this issue. Cloning of the membrane potential-generating citrate transporter (CitP) of Leuconostoc mesenteroides revealed an amino acid sequence that is almost identical to the known sequence of the CitP of Lactococcus lactis. The cloned gene was expressed in a Lactococcus lactis Cit− strain, and the gene product was functionally characterized in membrane vesicles. Uptake of citrate was counteracted by the membrane potential, and the transporter efficiently catalyzed heterologous citrate-lactate exchange. These properties are essential for generation of a membrane potential under physiological conditions and show that the Leuconostoc CitP retains its properties when it is embedded in the cytoplasmic membrane of Lactococcus lactis. Furthermore, using the same criteria and experimental approach, we demonstrated that the endogenous CitP of Lactococcus lactis has the same properties, showing that the few differences in the amino acid sequences of the CitPs of members of the two genera do not result in different catalytic mechanisms. The results strongly suggest that the energetics of citrate degradation in Lactococcus lactis and Leuconostoc mesenteroides are the same; i.e., citrate metabolism in Lactococcus lactis is a proton motive force-generating process.
TL;DR: The major organic acid in Garcinia cambogia (Malabar tamarind) has been found to be (−)-hydroxycitric acid, present in concentrations of 16-18%, using high-performance liquid chromatography with 10 mM sulfuric acid as eluent as discussed by the authors.
TL;DR: The effects of free radicals on the development of crystals attached to the living epithelium have been studied using an experimental model that enables close simulation of the conditions prevailing in the kidney and clearly demonstrate that free radical-damaged cells produce a favorable environment for crystal development.
Abstract: The effects of free radicals on the development of crystals attached to the living epithelium have been studied using an experimental model that enables close simulation of the conditions prevailing in the kidney. The results obtained clearly demonstrate that free radical-damaged cells produce a favorable environment for crystal development. At low free radical concentrations, crystals develop on calcium-enriched zones, whereas at higher concentrations, crystals develop on areas with a destroyed monolayer of superficial cells. Evaluation of the action of some products with antioxidant action and/or crytallization-inhibitory capacity is also included. Antioxidants, such as ascorbic acid and mannitol, exerted the most remarkable effects in avoiding calcium oxalate crystal development, whereas crystal inhibitors, such as citric acid, did not produce any remarkable reduction in calcium oxalate crystallization. Phytic acid notably decreased calcium oxalate crystal development. The ability of phytic acid to diminish calcium oxalate crystallization must be attributed to the combination of its inhibitory capacity of calcium oxalate crystallization and its preventive antioxidant action.
TL;DR: In this article, the antioxidant properties of grapefruit seed extract (GFSE) were investigated in vegetable oils, where different amounts of GFSE in powder were dissolved in a mixture of soybean oil and sunflower oil.
Abstract: The antioxidant activities of a grapefruit seed extract (GFSE) which contains tocopherols, citric acid and ascorbic acid, were investigated in vegetable oils. Different amounts of GFSE in powder were dissolved in a mixture of soybean oil–sunflower oil. The oxidation was carried out in an AOM equipment at temperatures of 98·7°C, 75°C and 66·5°C. The results indicated prooxidant effects of GFSE at 97·8°C and 75°C possibly due to a blockade effect of a hydroxyl compound by tocopherol. The inhibitor reaction orders at these temperatures were 0·902 and 0·465, respectively, while at 66·5°C the oxidation rate was inverse to GFSE concentration with reaction order of −0·420. These results seem to indicate different reaction mechanisms depending on temperature conditions. The blockade effects were explained on the basis of a proposed complex between tocopherol and citric acid molecules. © 1998 SCI.
TL;DR: The role of acidification and chelating agents in the solubilization of uranium (U) from contaminated soil was examined in a series of experiments as mentioned in this paper, which indicated that the addition of citric acid solubiliized more U than acidification or the other amendments tested.
Abstract: The role of acidification and chelating agents in the solubilization of uranium (U) from contaminated soil was examined in a series of experiments. Soil acidification and the addition of chelating agents were the two methods compared initially. The results indicated that the addition of citric acid solubilized more U than acidification or the other amendments tested. This increase in U solubility was, however, transitory. A subsequent experiment indicated that citrate concentration had a more dramatic effect on U solubility than did acidification. The greatest soluble U concentration during this experiment (775 mg kg -1 soil, or ∼85% of the total U) was observed after 24 h in the presence of 20 millimoles citrate kg -1 soil at pH 5. The persistence of U solubility over the 96-h experimental period was primarily a function of pH and citrate degradation. In a separate experiment, in which citric acid rather than citrate was added to contaminated soil, the soluble U concentrations observed were generally lower than those observed in the presence of citrate. Citric acid decreased soil pH to values ≤3.6, and solubilized higher concentrations of Al and Fe than observed in the presence of citrate. Since the maximum solubilization of U was observed at pH 5, the implication of these results is that a combined approach, using both soil acidification and citric acid addition, may be necessary to maximize the phytoextraction of U from soils with a pH > 6.0.