Uptake Of Ammonium Ions Research Articles

Preferential uptake of ammonium ions by zinc ferrocyanide.

The concentration of ammonia from dilute aqueous solution could have facilitated many prebiotic reactions. This may be especially true if this concentration involves incorporation into an organized medium. We have shown that (unlike iron(III) ferrocyanide) zinc ferrocyanide,Zn2Fe(CN)6 xH2O, preferentially takes up ammonium ions from 0.01 M NH4Cl to give the known material Zn3(NH4)2[Fe(CN)6]2 xH2O, even in the presence of 0.01 M KCl. KCl alone gave Zn3K2[Fe(CN)6]2 xH2O. Products were characterized by elemental (CHN) analysis and powder X-ray diffraction (XRD). We attribute the remarkable specificity for the ammonium ion to the open framework of the product, which offers enough space for hydrogen-bonded ammonium ions, and infer that other inorganic materials with internal spaces rich in water may show a similar preference.

Enhanced nutrient removal in high-rate ponds

High-rate ponding (HRP) processes have evolved from conventional oxidation ponds and could play an important role in the treatment of organic wastewaters in sunbelt communities requiring tertiary treatment. HRP systems are very efficient in removing biochemical oxygen demand, nitrogen, and phosphorus. Mineralized nitrogen is removed by algal uptake of ammonium ion (NH4+) and out-gassing of ammonia (NH3). High daytime pH generated in the pond due to algal uptake of bicarbonate shifts the equilibrium in favor of NH3. There are also two mechanisms for phosphorus removal in an HRP; algal uptake and chemical precipitation. Phosphorus uptake by algae is lower than nitrogen uptake because the nitrogen content of algae is approximately ten times more than the phosphorus content, which is approximately one percent of the 100 to 300 mg/l algal dry weights in an HRP. If sewage contains 10 mg/l of phosphorus, algal phosphorus uptake would be only 1 to 3 mg/l. Precipitation of phosphates with polyvalent cations such as calcium and magnesium also occurs in a HRP due to the high pH. This precipitation is sometimes called “autoflocculation”, which is often incomplete due to insufficient calcium and magnesium concentrations in the wastewater. In the case of Richmond, California, where the studies were conducted, the sewage has low magnesium and very low calcium concentrations. Enhancement of calcium and magnesium deficient autoflocculation was studied by adding 20 to 80 mg/l of freshly slaked lime to the pond during the continuous paddle wheel mixing. This simple procedure improved phosphorus, nitrogen and algae removal efficiencies to a level greater than 90%.

Enhanced nutrient removal in high-rate ponds

High-rate ponding (HRP) processes have evolved from conventional oxidation ponds and could play an important role in the treatment of organic wastewaters in sunbelt communities requiring tertiary treatment. HRP systems are very efficient in removing biochemical oxygen demand, nitrogen, and phosphorus. Mineralized nitrogen is removed by algal uptake of ammonium ion (NH4+) and out-gassing of ammonia (NH3). High daytime pH generated in the pond due to algal uptake of bicarbonate shifts the equilibrium in favor of NH3. There are also two mechanisms for phosphorus removal in an HRP; algal uptake and chemical precipitation. Phosphorus uptake by algae is lower than nitrogen uptake because the nitrogen content of algae is approximately ten times more than the phosphorus content, which is approximately one percent of the 100 to 300 mg/l algal dry weights in an HRP. If sewage contains 10 mg/l of phosphorus, algal phosphorus uptake would be only 1 to 3 mg/l. Precipitation of phosphates with polyvalent cations such as calcium and magnesium also occurs in a HRP due to the high pH. This precipitation is sometimes called "autoflocculation", which is often incomplete due to insufficient calcium and magnesium concentrations in the wastewater. In the case of Richmond, California, where the studies were conducted, the sewage has low magnesium and very low calcium concentrations. Enhancement of calcium and magnesium deficient autoflocculation was studied by adding 20 to 80 mg/l of freshly slaked lime to the pond during the continuous paddle wheel mixing. This simple procedure improved phosphorus, nitrogen and algae removal efficiencies to a level greater than 90%.

FERMENTATION OF WORTS MADE FROM 100% RAW SORGHUM AND ENZYMES

Worts made from raw sorghum and enzymes were successfully fermented even though the level of FAN present (51 mg/l) is well below that essential for fermentation of wort made from malted barley. Changes in typical fermentation parameters such as specific gravity, pH uptake of free amino nitrogen (FAN) and ammonium ions mirrored the increase in yeast cell concentration. Yeast viability remained high throughout the fermentation. Under identical fermentation conditions, malted barley worts showed typical fermentation profiles. However, malted barley worts with specific gravity maintained by the addition of D-glucose, but in which the FAN was diluted to a level similar to that found in a wort made from sorghum and enzymes, fermented more slowly and failed to attenuate fully. Five consecutive fermentations, using yeast cropped from the preceding to pitch the current fermentation were conducted. The specific gravity profiles were essentially the same in all five fermentations. Final values of pH, yeast in suspension, yeast viability and FAN were also indistinguishable. The yeast crop taken from fermentations of worts made from raw sorghum and enzymes represented a 5-fold increase over the initial pitching rate. When compared to commercial beers, the beers derived from fermentation of worts made from raw sorghum and enzymes contained lower levels of ethyl acetate, and higher levels of both 2- and 3-methyl butanol. In the beers derived from sorghum, isobutanol was always less than 20% of the total higher alcohol concentration.

Kinetics of the repression of tylosin biosynthesis by ammonium ion in Streptomyces fradiae

Nitrogen regulation of tylosin synthesis in Streptomyces fradiae NRRL 2702 was studied in batch and chemostat cultures using a soluble synthetic medium. In batch cultures, valine dehydrogenase (VDH; EC 1.4.1.8), threonine dehydratase (TDT; EC 4.2.1.16) and aspartate aminotransferase (ASAT; EC 2.6.1.1) reached their highest specific activities at 120 h. The specific activities of the three enzymes showed close correlation with the value of specific tylosin formation rate ( q TYL). In chemostat cultures, the maximum value of q TYL was 1.14 tylosin per mycelial mass per h (mg g −1 h −1) at the specific growth rate of 0.05 h −1, and after reaching a rate of 0.1 h −1, q TYL decreased with increasing levels of the specific growth rate. This value of q TYL was 3.5-times as large as that of maximum q TYL observed in the batch culture. The specific formation rates of VDH, TDT, ASAT and tylosin were repressed by high levels of specific ammonium ion uptake rate.

Simulation of water and nitrogen dynamics in soils during wastewater applications by using a finite-element model

A mathematical model was developed to simulate water movement, mass transport, and nitrogen transformations in soils during wastewater applications. The model is one-dimensional and based on the Galerkin finite-element method. The submodel of mass transport of nitrogen incorporates the convection-dispersion processes of ammonium and nitrate nitrogen, nitrification, denitrification, ammonium exchange and uptake of ammonium and nitrate ions. The accuracy and validity of the proposed model was examined by comparison with an explicit-implicit finite-difference model results. The model was used for simulation of water and nitrogen dynamics during wastewater application in homogeneous and multi-layered soils under different N concentration, rate, duration and scheduling of application.

Adaptive control of specific growth rate based on proton production in anaerobic fed-batch culture

This paper develops a practical and useful computer control scheme to control the specific growth rate as accurately as possible by measuring the released protons in anaerobic alcohol fermentation. In the case of current study, most of the released protons are due to the uptake of cationic ammonium ion via the conversion: NH4+ → NH3(cell) + H+. Correlating the Proton Production (PP) and the Proton Production Rate (PPR) with specific growth rate (μ) proved PP as a better measured variable. Using a simple adaptive control algorithm, μ was successfully controlled in a Zymomonas mobilis fed-batch culture.

Different ammonium-ion uptake, metabolism and detoxification efficiencies in two Lemnaceae

15N-Nuclear magnetic resonance spectroscopy was used to follow nitrogen assimilation and amino-acid production in Wolffia arrhiza (L.) Hork. ex. Wimmer, clone Golan exposed to 4.0 mM 15NH4Cl solutions for 24 h. The main 15N-labelled metabolites were asparagine and glutamine, as well as substantial amounts of unreacted, intracellular NH 4 + . These results were compared with those of a previous study on Lemna gibba L. clone Hurfeish (Monselise et al., 1987, New Phytol. 10, 341–345) with regard to NH 4 + uptake, assimilation and detoxification efficiencies. Both species, grown under continuous white light, were capable of preferential uptake of NH 4 + in the presence of nitrate. Relative growth rates indicate that both species tolerate increased levels of NH 4 + , up to 10−2 mol · 1−1, with L. gibba showing a slightly greater tolerance. No 15N-labelled free NH 4 + was detectable in L. gibba, while in W. arrhiza excess NH 4 + was found within the cells. This fact indicates that L. gibba is more efficient in detoxification than W. arrhiza, presumably because of inability of W. arrhiza to regenerate the “NH 4 + traps”, glutamate and aspartate, rapidly enough. This is also evident from the observation that addition of α-ketoglutarate to the medium caused nearly complete assimilation of intracellular NH 4 + in W. arrhiza. In both plants, addition of α-ketoglutarate increased both NH 4 + uptake and assimilation. Addition of l-methionine dl-sulfoximine, an inhibitor of glutamine synthetase inhibited NH 4 + assimilation, while addition of azaserine, an inhibitor of glutamate synthase, resulted in 15N incorporation into the glutamine-amide position only. These results are consistent with the glutamine synthetase-glutamate synthase pathway being the major route of NH 4 + assimilation in the two plants under the conditions used.

Causes of conductance change in yeast cultures.

The conductance change due to growth of Saccharomyces cerevisiae Y112, Zygosaccharomyces bailii M and Rhodotorula rubra NCYC 63 in culture media containing glucose, tartrate pH buffer and ammonium ions as sole nitrogen source was compared with that in a medium containing L-asparagine as sole nitrogen source. Decreases in conductance were observed in glucose-ammonium cultures of all three yeasts while little change occurred in cultures with L-asparagine as sole nitrogen source. This supports the hypothesis that the metabolic activity primarily responsible for conductance change in yeast cultures is the uptake of charged ammonium ions as nitrogen source and the reaction of protons with pH buffer compounds. Rhodotorula rubra cultures with L-asparagine as sole carbon source caused large increases in conductance with growth. Chemical analyses of culture filtrates showed that this increase in conductance was due to use of L-asparagine as carbon source and the excretion of nitrogen surplus to biosynthetic needs as ammonium. In addition, the production of aspartate, acetate and bicarbonate contributed to the increase in conductance.

Futile cycling of ammonium ions via the high affinity potassium uptake system (Kdp) of Escherichia coli

Escherichia coli Frag1 was grown under various nutrient limitations in chemostat culture at a fixed temperature, dilution rate and pH both in the presence and the absence of a high concentration of ammonium ions by using either ammonium chloride or DL-alanine as the sole nitrogen source. The presence of high concentrations of ammonium ions in the extracellular fluids of potassium-limited cultures of E. coli Frag1 caused an increase of the specific rate of oxygen consumption of these cultures. In contrast, under phosphate-, sulphate- or magnesium-limited growth conditions no such increase could be observed. The presence of high concentrations of ammonium ions in potassium-limited cultures of E. coli Frag5, a mutant strain of E. coli Frag1 which lacks the high affinity potassium uptake system (Kdp), did not increase the specific rate of oxygen consumption. These results indicate that ammonium ions, very similar to potassium ions both in charge and size, are transported via the Kdp leading to a futile cycle of ammonium ions and ammonia molecules (plus protons) across the cytoplasmic membrane. Both the uptake of ammonium ions and the extrusion of protons would increase the energy requirement of the cells and therefore increase their specific rate of oxygen consumption. The involvement of a (methyl)ammonium transport system in this futile cycle could be excluded.

Effect of acidification on uptake of rubidium, potassium and ammonium ions by spruce

Abstract Four series of experiments were conducted to determine how pH affects the uptake of ions by spruce (Picea abies). Each series consisted of 12 plants growing in nutrient solutions with pHs of 3.0, 3.5, 4.0 and 5.0, respectively. The uptake of Rb, K and NH4 was studied. The uptake of Rb and NH4 in relation to the uptake of K was pH dependent, plants chose Rb and NH4 before K, the reason explained with the aid of a model including binding energy, hydration energy and the charge on the carrier. This model could explain other patterns of uptake of ions according to changing pH as long as the same carrier is used. Furthermore, our results indicate that coniferous trees growing on low pH soils in areas with a heavy N load from the atmosphere could risk shortage of K. Additional field studies are needed for verification.

Substrate Utilization by Dendrobium Tissues

Glucose, fructose, and sucrose provide carbon sources for Dendrobium tissues. Fructose was the most readily utilized sugar. Sucrose was hydrolyzed extracellularly. Ammonium ion uptake far exceeded nitrate uptake. Significant nitrate uptake was evident only when the ammonium ion was totally depleted. Relative growth rate increased with increasing sugar concentration in the media and was most marked with fructose as the carbon source. A high respiration rate was observed for tissues grown in fructose or glucose but not in sucrose. Respiratory rate decreased with an increase in sugar concentration.

The Uptake of Ammonium, Nitrite and Nitrate Ions by Hydrodictyon reticulatum

AbstractIt has been found that ammonium ions belong together with potassium and sodium ions to the main cationic species in algal cells. The intracellular concentration of ammonium ions, which changes from 4 to 160 μmol. g−1 wet weight, strongly influences the influx and reflux of different ions. Algal cells containing 4… 6 μmol of ammonium ions per gram cumulate ammonium ions in the light with a very high initial rate of 40… 80 pmol. cm−2. s−1, whereas the influx of nitrite or nitrate ions is slower by more than one order. Whereas ammonium ions simply displace potassium ions from the cell, the uptake of nitrite and nitrate ions is more complicated. These ions are rapidly reduced inside the cell into ammonium ions, which is connected with the reflux of potassium and hydroxyl ions. Ammonium ions formed take part in metabolic reactions releasing hydrogen ions.

Effects of root temperature on uptake of nitrate and ammonium ions by barley grown in flowing-solution culture

Effects of root temperature on uptake of nitrate and ammonium ions by barley grown in flowing-solution culture

PARTIAL RECOVERY IN PLASTIDS OF LEMNA AEQUINOCTIALIS WELWITSCH * 1073 TREATED WITH l‐METHIONINE OR l‐CYSTINE

SUMMARYWhen light‐grown plants of mutant 1073 of Lemna aequinoctialis Welwitsch were grown in a medium containing 31 μl‐cystine, the tubular clusters characteristic of this mutant disappeared in the mature fronds and chloroplasts and mitochondria appeared normal. l‐Methionine (2 μ) effected a similar but less dramatic change. In young fronds, however, 10% of chloroplasts when supplied with l‐cystine, and 50% when supplied with l‐methionine, still contained tubular clusters.When l‐cystine was supplied to young fronds of the wild‐type strain 6746, chloroplasts were normal but contained much larger starch inclusions. Relative growth rates of both strains were improved by addition of l‐cystine or l‐methionine. In mutant fronds they attained values equivalent to wild‐type control. This partial recovery from ultrastructural defects was not matched by a physiological recovery, i.e. plants were still incapable of photosynthesis and ammonium ion uptake, as were mutant plants in control media.Moreover when the partially recovered plants were tested for ammonium ion uptake, in the presence of either l‐methionine or l‐cystine, ammonium ions from plants moved out into the medium during the first 24 h, while increased ammonium uptake was detected with the wild strain.

Ammonia Transport in Free-living and Symbiotic Rhizobium sp. ANU289

Summary: [14C]Methylamine uptake by free-living Rhizobium sp. ANU289 had Michaelis–Menten kinetics (apparent K m 6.6 μm). Uptake was competitively inhibited by ammonia (K i 0.4 μm) and was dependent on an energized membrane. Uptake by bacteria had an optimum at pH 7.0. Methylamine uptake by bacteroids from siratro root nodules was much slower than that by free-living bacteria at pH 7.0 but increased exponentially with the pH of the medium. Uptake by bacteroids did not show saturation kinetics and was insensitive to the presence of ammonia or uncouplers. These results suggest that free-living bacteria (grown under conditions where ammonia is limiting) have an active transport mechanism for the uptake of ammonium ions; this carrier is not operative in the symbiotic state, where passive diffusion of ammonia occurs. In the free-living state, the ammonium carrier is under genetic control, being repressed by growth on high concentrations of ammonia. Derepression occurs under conditions of nitrogen starvation.

Whole Plant Studies using Radioactive 13-Nitrogen

Presland, M. R. and McNaughton, G. S. 1986. Whole plant studies using radioactive 13-nitrogen IV. A compartmental model for the uptake and transport of ammonium ions by Zea mays.—J exp. Bot. 37: 1619–1632 Ammonium ion uptake by roots of hydroponically grown maize seedlings and the transport of ammonium-sourced nitrogen to the shoot were measured using the short-lived isotope 13-nitrogen. They are shown to be described by a five compartment model—ammonium in the root bathing solution, ammonium entering the root, nitrogen bound in the root, nitrogen outside the load region but still within the root, and nitrogen in the shoot. Once taken into the root symplasm, ammonium-sourced nitrogen was not exchanged with the external solution. Activity-time profiles for nitrogen transported both basally and apically from the load region of the root implied the existence of large well-mixed pools in the transport path, though the capacity of the pools inferred from modelling the profiles was greater than found by dissecting roots following loading with labelled ammonium.

Peptide Alcohols as Promoters of Nitrate and Ammonium Ion Uptake in Plants

Several aryl-carbamoyl dipeptide alcohols increased the uptake of nitrate and ammonium ions into corn root segments by up to 50% and 90%, respectively. The most effective one was N-carbobenzoxy-l-prolyl-l-valinol. Foliar application of this compound to underfertilized corn plants caused an increase in the rate of plant growth in the greenhouse and provided modest (6-10%) corn yield increases in field tests in Delaware.

UNUSUAL ‘TUBULAR CLUSTERS’ IN THE PLASTIDS OF A DUCKWEED (LEMNA PAUCICOSTATA) MUTANT INCAPABLE OF PHOTOSYNTHESIS AND AMMONIUM ION UPTAKE

SummaryLight‐grown plants of the wild type 6746 strain and the mutant strain 1073 of Lemna paucicostata were compared. It was confirmed that this photosynthetically defective mutant is dependent on supply of sucrose for its growth. Moreover it was found that it is unable to take up NH4+ in the absence of added sucrose; addition of a‐oxoglutarate did not allow ammonium ion uptake.In the mutant, mitochondria are unusually long and distorted and in its chloroplasts the grana contain many more thylakoid membranes than in the wild‐type chloroplasts of the same age. Moreover, at all ages, the presence of specific new structures known as ‘tubular clusters’ can be detected; tubular clusters differ from prolamellar bodies found in etioplasts. In addition, both strains produced in young fronds, upon standing in darkness for 28 h, prolamella bodies with typical crystalline structure.A possible connection between the tubular clusters and physiological aberrations of the mutant is discussed.

Light-limited growth of two strains of the marine diatom Phaeodactylum tricornutum Bohlin: Chemical composition, carbon partitioning and the diel periodicity of physiological processes

Two isolates of the marine pennate diatom Phaeodactylum tricornutum Bohlin were grown in semi-continuous, nutrient-sufficient culture at varying irradiances on a 12-h light, 12-h dark illumination cycle. The reponse of the isolates to varying degrees of light limitation differed with respect to all of the compositional parameters measured, including growth rates, elemental composition, chlorophyll content, and the partitioning of cellular carbon into four biochemical classes: proteins, lipids, polysaccharides, and low-molecular weight intermediates. The isolates also differed with respect to the relative contributions of light-period and dark-period uptake to the total uptake of ammonium and phosphate ions, although in all cases uptake took place at a reduced rate in the dark. They did not differ with respect to the diel periodicity of cell division, chlorophyll synthesis, and biochemical synthesis. Slightly more cell division took place during the dark period than during the light period. The specific rate of chlorophyll synthesis in the light period, when expressed as a function of irradiance, saturated rapidly; the rate was nearly constant for all irradiances > 100 βE · m −2 · s −1. Chlorophyll synthesis in the dark was positively correlated with irradiance over the entire range of irradiances, except where photoinhibition was involved. Protein was synthesized in both the light and dark periods, but at a reduced rate in the dark. Polysaccharides were synthesized during the light period and consumed during the dark period. Lipids and low molecular weight intermediates were synthesized during the light period, but showed little net change during the dark period.