The mechanism of action of ethanolamine ammonia-lyase, a B 12 -dependent enzyme. IX. Interaction of the enzyme-coenzyme complex with reaction products.
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Acetaldehyde↗
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Nutritional potential of nitrogen recycling in man.
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Amino Acids↗
Competition between ammonia derived from internal glutamine hydrolysis and hydroxylamine present in the solution for incorporation into UTP as catalysed by Lactococcus lactis CTP synthase.
CTP synthase catalyses the reaction: glutamine+UTP+ATP --> glutamate+CTP+ADP+P(i). The reaction is greatly stimulated by the allosteric binding of GTP. In addition to glutamine that is hydrolysed by the enzyme to ammonia and glutamate, CTP synthase will also utilise external sources of amino donors such as NH(4)Cl. This reaction is no longer dependent on allosteric activation by GTP. Hydroxylamine is also a substrate for Lactococcus lactis CTP synthase and results in the formation of N4-OH CTP. This product has the feature that it absorbs at 300nm where CTP absorption was shown to be greatly reduced and enabled the determination of N4-OH CTP formation in the presence of CTP synthesis derived from glutamine hydrolysis. Differences in initial rates determined for the hydroxylamine dependent reaction at 291nm in the presence and absence of glutamine and GTP were ascribed to simultaneous CTP and N4-OH CTP synthesis in the presence of these compounds. A characterisation of the apparent inhibition by GTP and glutamine of N4-OH CTP synthesis determined at 300nm showed that glutamine dependent CTP synthesis occurs at a rate of about 60% of that in the absence of hydroxylamine. GTP dependent inhibition of the ammonium chloride dependent reaction of L. lactis CTP synthase by the glutamine analog glutamate gamma-semialdehyde showed a partial inhibition with a maximum inhibition of about 60%. These results are interpreted in terms of a "half of the sites" mechanism for glutamine hydrolysis on CTP synthase.
Ammonia↗
The incorporation of nitrogen into products of recent photosynthesis in Anabaena cylindrica Lemm.
In vivo tracer studies with 14C have been performed to help determine pathways of incorporation of newly assimilated nitrogen into N2-fixing cells of Anabaena cylindrica. After photosynthesis in Ar: O2:14CO2 for 30 min, the addition of N2 or NH+4 resulted in increased rates of 14CO2-incorporation both in the light and dark, and in increased incorporation of 14C into amino acids at the expense of sucrose and sugar phosphates. Evidence of enhanced sucrose catabolism and increased pyruvate kinase activity was obtained on adding nitrogen, and, of the 14C-labelling entering the tricarboxylic acid cycle, more appeared in citrate and 2-oxoglutarate than in malate and oxaloacetate. The kinetics of 14C-incorporation into various amino acids suggest that in the light and dark the most important route of primary ammonia assimilation involves glutamine synthetase and that glutamate, aspartate, glycine and probably alanine are formed secondarily from glutamine.
Alanine↗
Photocatalytic degradation of explosives contaminated water.
This study was undertaken to examine the degradation of TNT, RDX and HMX in a circular photocatalytic reactor with TiO2 as a photocatalyst. We examined the impact of parameters such as the initial concentration, initial pH of solution on rates of photocatalized transformation, and the mineralization. The results showed that photocatalysis is an effective process for the degradation of TNT, RDX and HMX. They could be comoletely degraded in 150 min with 1.0 g/L TiO2 at pH 7. An increase in the photocatalytic degradation of HMX was noticed with decreasing initial HMX. The rates of RDX and HMX degradation were greater in neutral pH than in acidic and alkaline conditions. In case of TNT degradation, the rate of degradation was the fastest at pH 11. Approximately 82% TOC decrease in the TNT degradation was achieved after 150 min, whereas TOC decrease in RDX and HMX was 24% and 59%, respectively. Nitrate, nitrite, and ammonium ions were detected as the nitrogen byproducts from the photocatalysis, and more than 50% of the total nitrogen was recovered as nitrate ion in every explosives.
Ammonia↗
Anammox transited from denitrification in upflow biofilm reactor.
Anammox was successfully transited from heterotrophic denitrification and autotrophic denitrification in two upflow biofilm reactors, respectively. The results showed that the volumetric loading rate and nitrogen removal efficiency in the reactor transited from heterotrophic denitrification were higher than that in its counterpart. When the hydraulic retention time was 12 h or so, the total nitrogen loading rate was about 0.609 kg N/(m3 x d), and the effluent ammonia and nitrite concentrations were less than 8.5 mg/L and 2.5 mg/L, respectively. The upflow anammox biofilm reactor was capable of keeping and accumulating the slow-growing bacteria efficiently. During operation of the reactor, the biomass color was gradually turned from brownish to red, and the ratio of ammonia consumption, nitrite consumption and nitrate production approached the theoretical one. These changes could be used as an indicator for working state of the reactor.
Biofilms↗
Feasibility of a combined carrier test for disinfectants: studies with a mixture of five types of microorganisms.
BACKGROUND: There is mounting concern regarding the efficacy of many germicides on the market because officially recognized germicidal tests for various classes of microorganisms vary widely and often lack reproducibility and proper quantitation. We report here a carrier method for simultaneously and quantitatively assessing the efficacy of liquid chemical germicides against a mixture of microorganisms of varying degrees of resistance. METHODS: In the test, each small glass cup (10 mm wide x 14 mm long) was contaminated with 10 microliters of a standardized mixture of Staphylococcus aureus, Mycobacterium bovis bacille Calmette-Guérin, Trichophyton mentagrophytes spores, Sabin poliovirus type 1, and Bacillus stearothermophilus spores in 5% fetal bovine serum. The inoculum was dried for 60 minutes under ambient conditions and covered with 60 microliters of the disinfectant under test or a balanced salt solution control for the desired contact time. The carrier was then placed in 2940 microliters of an eluent and the eluates assayed separately for the five microorganisms. Tap water was used to dilute the test product as needed. RESULTS: Of the 11 products tested, 2% alkaline glutaraldehyde, 0.6% sodium hypochlorite (about 5000 ppm free chlorine), and a 0.4% quarternary ammonium compound containing 23% hydrochloric acid were effective against all five challenge organisms. A hard-surface spray containing 0.1% o-phenylphenol with 79% ethanol was effective against all but bacterial spores; 70% (volume/volume) ethanol alone and povidone-iodine (1% available iodine) were effective against S. aureus, the mycobacterium, and the fungus; a 3% solution of peroxygen compounds was effective only against S. aureus and the poliovirus; 1.5% chlorhexidine gluconate, 0.06% quaternary ammonia compound, and 0.03% o-phenylphenol + 0.03% p-tertiary amylphenol could inactivate nothing but S. aureus; and 3% hydrogen peroxide was ineffective in all tests. CONCLUSIONS: This method shows promise for use with various classes of microorganisms, individually or as mixtures. Its application should enable the classification of germicides according to spectrum of activity.
Disinfectants↗
The astrocyte response in experimental portal-systemic encephalopathy: an electron microscopic study.
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Ammonia↗
Nitrification and autotrophic nitrifying bacteria in a hydrocarbon-polluted soil.
In vitro ammonia-oxidizing bacteria are capable of oxidizing hydrocarbons incompletely. This transformation is accompanied by competitive inhibition of ammonia monooxygenase, the first key enzyme in nitrification. The effect of hydrocarbon pollution on soil nitrification was examined in situ. In a microcosm study, adding diesel fuel hydrocarbon to an uncontaminated soil (agricultural unfertilized soil) treated with ammonium sulfate dramatically reduced the amount of KCl-extractable nitrate but stimulated ammonium consumption. In a soil with long history of pollution that was treated with ammonium sulfate, 90% of the ammonium was transformed into nitrate after 3 weeks of incubation. Nitrate production was twofold higher in the contaminated soil than in the agricultural soil to which hydrocarbon was not added. To assess if ammonia-oxidizing bacteria acquired resistance to inhibition by hydrocarbon, the contaminated soil was reexposed to diesel fuel. Ammonium consumption was not affected, but nitrate production was 30% lower than nitrate production in the absence of hydrocarbon. The apparent reduction in nitrification resulted from immobilization of ammonium by hydrocarbon-stimulated microbial activity. These results indicated that the hydrocarbon inhibited nitrification in the noncontaminated soil (agricultural soil) and that ammonia-oxidizing bacteria in the polluted soil acquired resistance to inhibition by the hydrocarbon, possibly by increasing the affinity of nitrifying bacteria for ammonium in the soil.
Colony Count, Microbial↗
Sodium citrate supplementation in inborn argininosuccinate lyase deficiency: a study in a 5-year-old patient under total parenteral nutrition.
The effects of sodium citrate supplementation to improve aspartic acid supply in a 5-year-old girl with argininosuccinate lyase deficiency were studied over a period of 5 years under constant and total parenteral nutrition. Daily increasing doses of sodium citrate (0-8 mmol/kg) were continuously infused i.v.. Her standard therapy with arginine hydrochloride (4 mmol/kg/day) and sodium benzoate (200 mg/kg/day) was continued. Serum citrulline concentrations were reduced by citrate supplementation (161.8-41.7 mumol/l). Correspondingly serum concentrations of argininosuccinate and its anhydrides rose (270-458 mumol/l), positively correlated with the doses of sodium citrate. Renal elimination of argininosuccinate did not change measurably. There was no improvement in plasma ammonia concentration, which remained between 88 and 136 mumol/l. A long-standing hepatomegaly did not improve. The patient developed a significant alkalosis with blood pH-values increasing up to 7.55. The alkalosis lead to a reduction in renal ammonium elimination by at least 5.3 mmol/kg per day; the portion of ammonium-nitrogen decreased from 54.2% to finally 9% of total urinary nitrogen. Nevertheless total urinary nitrogen elimination, as measured by pyrochemiluminescence, improved by 24.5% during the 5 days and rose from 2065 mg nitrogen/day to 2570 mg/day. This improvement could not be explained by the metabolites determined and corresponded with an increase in chemically undefined nitrogen excretion, which rose from 0% to 65.9% of total urinary nitrogen. Further investigations are necessary to elucidate the nature of these unexplained nitrogen-containing compounds. CONCLUSION. Sodium citrate supplementation improved renal nitrogen elimination in a patient with argininosuccinate lyase deficiency in the observation period of 5 days by up to 24.5%.
Alkalosis↗
Effects of ammonia in vitro on endogenous taurine efflux and cell volume in rat cerebrocortical minislices: influence of inhibitors of volume-sensitive amino acid transport.
Rat cerebrocortical minislices were incubated with physiological saline in the absence or presence of 5 mM ammonium acetate ("ammonia") and/or inhibitors of osmosensitive amino acid transport: 50 microM niflumic acid and 100 microM N-ethyl-maleimide for 60 min, with medium changes after 20 min and 40 min. The efflux of endogenous taurine, glutamate and glutamine was assayed by high-performance liquid chromatography, and steady-state cell volumes were monitored in the slices with the [14C]inulin method. In the absence of ammonia, niflumic acid abolished taurine efflux but did not affect glutamate or glutamine efflux at all time-points, and increased cell volume at 20 min and 60 min. N-Ethyl-maleimide increased taurine, glutamine and glutamate efflux at 20 min and 40 min, inhibited taurine and glutamine efflux at 60 min, and increased cell volume at 20 min. Ammonia strongly stimulated taurine (by 380% at 20 min), and only moderately glutamate (30% at 20 min) or glutamine efflux (76% at 20 min). Ammonia increased cell volume above the control level at all time-points. Niflumic acid inhibited, but did not abolish ammonia-dependent taurine and glutamine efflux, and did not change glutamate efflux. The effects of ammonia + niflumic acid on cell volume did not differ from the effects of each compound separately. N-Ethyl-maleimide inhibited ammonia-dependent efflux of all three amino acids except for stimulation of glutamate efflux at 20 min. N-Ethyl-maleimide + ammonia decreased the cell volumes more than did each compound separately. It is concluded that although ammonia-induced taurine efflux is accompanied by an increase in cell volume, the underlying mechanism is not simply a cell volume regulatory response normally observed in hypoosmotic stress. Increased efflux of taurine, which is an inhibitory amino acid and a cell membrane protectant, may serve to counteract the deleterious effects of increased excitatory transmission accompanying acute hyperammonemic insult.
Ammonia↗
Nitrogen source and the retrograde signalling pathway affect detection, not generation, of the [URE3] prion.
[URE3] is an infectious (prion) inactive amyloid form of Ure2p, a regulator of nitrogen catabolism. [URE3] clones are selected on NH(4) (+), using their derepressed expression of DAL5 to allow uptake of ureidosuccinate (USA). We previously reported that mks1Delta prevents generation of [URE3] and others reported that glutamate in the medium or the elevated glutamate in mks1Delta strains blocks [URE3] generation. We show here that elevated glutamate does not block [URE3] generation, but that neither does mks1Delta. Rather, a post-transcriptional effect on DAL5 of mks1Delta through the retrograde regulation pathway prevents detection of [URE3] prion-containing colonies. Moreover, the presence of both ammonia and glutamate blocks USA uptake in a known [URE3] strain, so that detection of the prion is prevented, rather than its generation.
Glutamic Acid↗
(13)C incorporation into DNA as a means of identifying the active components of ammonia-oxidizer populations.
AIMS: To identify active CO2-assimilating species of ammonia-oxidizing bacteria in fresh water sediment. METHODS AND RESULTS: Enrichment cultures were incubated in the presence of 13C labelled CO2, and 13C-DNA successfully resolved from 12C-DNA by caesium chloride density gradient ultracentrifugation of DNA extracts. Ammonia-oxidizer DNA recovered from these gradients was amplified and characterised by Temporal Temperature Gradient Gel Electrophoresis (TTGE), with confirmatory sequence analysis to identify the metabolically active components of the population. CONCLUSION: The 12C-DNA fraction was dominated by nitrosospiras, in contrast to the 13C-DNA fraction which was largely nitrosomonad DNA, in support of the hypothesis that nitrosomonads out-compete nitrosospiras in laboratory culture. SIGNIFICANCE AND IMPACT OF THE STUDY: The use of stable isotype incorporation into ammonia-oxidizer DNA could therefore circumvent the problems associated with RNA detection to identify metabolically active species in situ.
Carbon Dioxide↗
Antisense reduction of serine hydroxymethyltransferase results in diurnal displacement of NH4+ assimilation in leaves of Solanum tuberosum.
Serine hydroxymethyltransferase (SHMT) is part of the mitochondrial enzyme complex catalysing the photorespiratory production of serine, ammonium and CO(2) from glycine. Potato plants (Solanum tuberosum cv. Solara) with antisensed SHMT were generated to investigate whether photorespiratory intermediates accumulated during light lead to nocturnal activation of the nitrogen-assimilating enzymes glutamine synthetase (GS) and glutamate synthase (GOGAT). The transformant lines contained 70-90% less SHMT protein, and exhibited a corresponding decrease in mitochondrial SHMT activity. SHMT antisense plants displayed lower photosynthetic capacity and accumulated glycine in light. Glycine was converted to serine in the second half of the light period, while serine, ammonium and glutamine showed an inverse diurnal rhythm and reached highest values in darkness. GS/GOGAT protein levels and activities in the transgenics also reached maximum levels in darkness. The diurnal displacement of NH(4)(+) assimilation was accompanied by a change in the subunit composition of GS(2), but not GS(1). It is concluded that internal accumulation of post-photorespiratory ammonium is leading to nocturnal activation of GS/GOGAT, and that the time shift in ammonia assimilation can constitute part of a strategy to survive photorespiratory impairment.
Amino Acids↗
DNA-dependent RNA polymerase from the thermophilic bacterium Thermus aquaticus.
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Ammonia↗
Difficulties in maintaining long-term partial nitritation of ammonium-rich sludge digester liquids in a moving-bed biofilm reactor (MBBR).
Nitrogen can be eliminated effectively from sludge digester effluents by anaerobic ammonium oxidation (anammox), but 55-60% of the ammonium must first be oxidized to nitrite. Although a continuous flow stirred tank reactor (CSTR) with suspended biomass could be used, its hydraulic dilution rate is limited to 0.8-1 d(-1) (30 degrees C). Higher specific nitrite production rates can be achieved by sludge retention, as shown here for a moving-bed biofilm reactor (MBBR) with Kaldnes carriers on laboratory and pilot scales. The maximum nitrite production rate amounted to 2.7 gNO2-Nm(-2)d(-1) (3 gO2m(-3)d(-1), 30.5 degrees C), thus doubling the dilution rate compared to CSTR operation with suspended biomass for a supernatant with 700 gNH4-Nm(-3). Whenever the available alkalinity was fully consumed, an optimal amount of nitrite was produced. However, a significant amount of nitrate was produced after 11 months of operation, making the effluent unsuitable for anaerobic ammonium oxidation. Because the sludge retention time (SRT) is relatively long in biofilm systems, slow growth of nitrite oxidizers occurs. None of the selection criteria applied - a high ammonium loading rate, high free ammonia or low oxygen concentration - led to selective suppression of nitrite oxidation. A CSTR or SBR with suspended biomass is consequently recommended for full-scale operation.
Bacteria, Anaerobic↗
[Effect of osmotic pressure on nitrification].
The effect of osmotic pressure on nitrification was investigated in the internal-loop air-lift nitrifying reactor. When influent ammonia concentration is kept at 420mg x L(-1) and influent osmotic pressure is increased from 4.3 to 18.8 x 10(5) Pa, the ammonia conversion of the nitrifying bioreactor is maintained between 93% and 100%. After influent osmotic pressure is further increased to 19.2 x 10(5)Pa, the ammonia conversion goes down to 69.2%. The influence of osmotic pressure on nitrification takes place without any alarm and the critical osmotic pressure is between 18.8 x 10(5) and 19.2 x 10(5) Pa. During osmotic stress, the nitrifying bacterial populations in the activated sludge become simplified, the cell size becomes smaller, the inner membrane becomes less and some unknown inclusion particles are formed. The cell structure is restored as soon as the osmotic pressure is removed. Addition of potassium is able to relieve the effect of osmotic pressure on nitrification. The nitrifying activity of the activated sludge is stimulated by the osmotic stress, and the specific ammonia conversion is increased from 0.083 kg x kg(-1) x d(-1) to 0.509 kg x kg(-1) x d(-1) and 2.569 kg x kg(-1) x d(-1), respectively.
Bioreactors↗
[Hygienic evaluation of technological, design and sanitary-technical solutions for large-scale chemical plants].
Complexes of technologic solution for the construction of large-scale plants producing ammonia, nitric and sulfuric acids, ammonium nitrate, carbomide and caprolactam , are characterized by both positive and negative hygienic features. The hygienic shortcomings reveal themselves in sporadic increases of hazardous ingredients in concentrations up to the MAC and higher levels, as well as in unfavorable labour conditions when dealing with catalysts, storage operations, inter-enterprise transportation, dispatching of raw materials and finished products, in the contamination of the in-going ventilation air, and in the compound influence of low temperatures and toxic substances. The concentration of several large-capacity enterprises in the same area entails large-scale discharges in the atmosphere with subsequent contamination of the surrounding protection areas. The author proposes a set of major preventive measures.
Air Pollution↗