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PubMed1977

Utilization of 15N-urea administered into the sheep small intestine.

The retention and excretion of intrajejunally administered 15N-urea was studied in four experiments on two sheep with a permanently fistulated small intestine. In the first 7 days after the administration of 2 g 15N-urea, 18.26% was excreted in the faeces and 19% in the urine; 62.74% was retained in the organism. Urinary excretion took place mainly on the first day and from the 3rd to the 7th day no 15N was present in the urine. The rate of 15N excretion in the faeces was roughly the same for the first 4 days and then fell; on the 7th day there was no 15N in the faeces. The proportion of 15N-urea retained in the organism and excreted in the urine was 81% showing that urea in the ruminant gastrointestinal tract is largely linked up into metabolic circulation as part of the general exchange of nitrogenous compounds.

Animals↗
PubMed1977

Nitrogen 15 tracer studies on the pathway of denitrification in Pseudomonas aeruginosa.

The pathway of anaerobic reduction of nitrite to nitrogen gas (N2) by cell suspensions of the denitrifier, Pseudomonas aeruginosa, was studied using the techniques of gas chromatography and mass spectrometry. While release of nitrous oxide (N2O) is not normally detected during the reduction of nitrite to N2 by this organism, 15N from [15N]nitrite nevertheless can be trapped quantitatively as 15N2O in a pool of added N2O. In such experiments the abundance of 15N in N2O always exceeds that in product N2, consistent with the absence of a major reductive route from nitrite to N2 which by-passes N2O. During the reduction of a mixture of [15N]nitrite and nitric oxide (NO), 15NO produced at most only in trace amounts. The final products are chiefly 15N2 and 14N2 with only a small fraction of the scrambled product, 14N15N. Much of the 14N15N can be accounted for as an artifact caused by traces of molecular oxygen, which promote the conversion of NO to nitrite by autooxidation and thereby degrade slightly the isotopic purity of [15N]nitrite. Nitrous oxide shows all the properties of a free obligatory intermediate during the denitrification of nitrite to N2 by P. aeruginosa, whereas NO does not. The inability to trap 15NO in a pool of NO indicates that NO is not a free obligatory intermediate in the reduction of nitrite. The small mole fractions of 14N15N produced from a mixture of [15N]nitrite and NO require that the main reductive pathways for these nitrogen oxides cannot share any freely diffusible mono-nitrogen intermediate in common. The simplest interpretation is that nitrite and NO are denitrified by separate pathways, at least prior to the formation of the first bi-nitrogen compound.

Anaerobiosis↗
PubMed1984

Total parenteral nutrition in sick preterm infants: effects of cysteine supplementation with nitrogen intakes of 240 and 400 mg/kg/day.

The effects of supplementing total parenteral nutrition (TPN) solutions with cysteine were assessed at two different levels of nitrogen intake by determining nitrogen retention, sulfate excretion, and sulfur-containing amino acid concentrations. Ten infants received 72 mg/kg/day of cysteine-HCl in a TPN solution for a period of 6 days. Five of these infants received 251 +/- 48 (mean +/- SD) mg/kg/day of nitrogen, and five received 403 +/- 45 mg/kg/day of nitrogen. Two other groups of five infants each received unsupplemented TPN at nitrogen intakes of 235 +/- 48 and 412 +/- 54 mg/kg/day, respectively. Fluid and nonprotein caloric intakes were similar for all four groups. Cysteine supplementation increased plasma and urine free cyst(e)ine concentrations and enhanced total sulfur retention, but did not enhance nitrogen retention. [Cyst(e)ine refers to the mixture in any proportion of the sulfhydryl (cysteine) and the disulfide (cystine) forms of this compound.] Nitrogen retention, sulfate excretion, cyst(e)ine excretion, and plasma taurine concentrations increased as the result of the increase in nitrogen intake.

Cysteine↗
PubMed2003

Summary of regulatory/policy/economic issues related to nitrogen.

This is a summary of the two presentations from the session that dealt with the regulatory, policy and economic issues related to nitrogen compounds and the need to reduce their emissions. The papers were presented by Ronald Evans and Jan Willem Erisman. Information on ecological impacts of nitrogen species and atmospheric relationships are presented in other papers in this special issue. This summary provides an overview of the discussions from the above presentations.

Air Pollutants↗
PubMed1984

Bacterial microflora of nitrogen industry wastewaters.

The quantitative and qualitative composition of heterotrophic bacteria found in two types of wastewaters from the nitrogen industry was determined. The number of bacteria in the wastewaters was 10(4) to 10(6) cells/ml. Gram-negative bacteria accounted for 57% of the bacteria in the final retention reservoir whereas their number in the wastewaters discharged into surface waters was 90%. The dominating species among the Gram-negative bacteria was Pseudomonas, irrespective of the composition of the wastes and means by which they were discharged into the Wisła. The studied microflora utilized in different metabolic processes nitrogen compounds present in the wastes.

Bacteria↗
PubMed2003

New concepts of microbial treatment processes for the nitrogen removal in wastewater.

Many countries strive to reduce the emissions of nitrogen compounds (ammonia, nitrate, NOx) to the surface waters and the atmosphere. Since mainstream domestic wastewater treatment systems are usually already overloaded with ammonia, a dedicated nitrogen removal from concentrated secondary or industrial wastewaters is often more cost-effective than the disposal of such wastes to domestic wastewater treatment. The cost-effectiveness of separate treatment has increased dramatically in the past few years, since several processes for the biological removal of ammonia from concentrated waste streams have become available. Here, we review those processes that make use of new concepts in microbiology: partial nitrification, nitrifier denitrification and anaerobic ammonia oxidation (the anammox process). These processes target the removal of ammonia from gases, and ammonium-bicarbonate from concentrated wastewaters (i.e. sludge liquor and landfill leachate). The review addresses the microbiology, its consequences for their application, the current status regarding application, and the future developments.

Industrial Microbiology↗
PubMed2000

Are microorganisms more effective than plants at competing for nitrogen?

Plant scientists have long debated whether plants or microorganisms are the superior competitor for nitrogen in terrestrial ecosystems. Microorganisms have traditionally been viewed as the victors but recent evidence that plants can take up organic nitrogen compounds intact and can successfully acquire N from organic patches in soil raises the question anew. We argue that the key determinants of 'success' in nitrogen competition are spatial differences in nitrogen availability and in root and microbial distributions, together with temporal differences in microbial and root turnover. Consequently, it is not possible to discuss plant-microorganism competition without taking into account this spatiotemporal context.

Fungi↗
PubMed1980

Asparagine formation in soybean nodules.

(15)NH(4) (+) and [(15)N](amide)-glutamine externally supplied to detached nodules from soybean plants (cv. Tamanishiki) were incorporated within nodule tissues by vacuum infiltration and metabolized to various nitrogen compounds during 60 minutes of incubation time. In the case of (15)NH(4) (+) - feeding, the (15)N abundance ratio was highest in the amide nitrogen of glutamine, followed by glutamate and the amide nitrogen of asparagine. In (15)N content (micrograms excess (15)N), the amide nitrogen of asparagine was most highly enriched after 60 minutes. (15)NH(4) (+) was also appreciably assimilated into alanine.When [(15)N](amide)-glutamine was fed to detached nodules, (15)N was almost entirely in the amide nitrogen of asparagine. The result indicates the presence of active glutamine-linked asparagine synthesizing systems in soybean root nodules.

Journal Article↗
PubMed1998

Improvement of nitrogen assimilation and fermentation kinetics under enological conditions by derepression of alternative nitrogen-assimilatory pathways in an industrial Saccharomyces cerevisiae strain.

Metabolism of nitrogen compounds by yeasts affects the efficiency of wine fermentation. Ammonium ions, normally present in grape musts, reduce catabolic enzyme levels and transport activities for nonpreferred nitrogen sources. This nitrogen catabolite repression severely impairs the utilization of proline and arginine, both common nitrogen sources in grape juice that require the proline utilization pathway for their assimilation. We attempted to improve fermentation performance by genetic alteration of the regulation of nitrogen-assimilatory pathways in Saccharomyces cerevisiae. One mutant carrying a recessive allele of ure2 was isolated from an industrial S. cerevisiae strain. This mutation strongly deregulated the proline utilization pathway. Fermentation kinetics of this mutant were studied under enological conditions on simulated standard grape juices with various nitrogen levels. Mutant strains produced more biomass and exhibited a higher maximum CO2 production rate than the wild type. These differences were primarily due to the derepression of amino acid utilization pathways. When low amounts of dissolved oxygen were added, the mutants could assimilate proline. Biomass yield and fermentation rate were consequently increased, and the duration of the fermentation was substantially shortened. S. cerevisiae strains lacking URE2 function could improve alcoholic fermentation of natural media where proline and other poorly assimilated amino acids are the major potential nitrogen source, as is the case for most fruit juices and grape musts.

Crosses, Genetic↗
PubMed2001

Enzymatic treatment of sanitary landfill leachate.

The objective of this investigation was to study the effectiveness of applying enzymes (bioaugmentation) for enhancement of biological treatability of leachates generated in a typical municipal solid waste sanitary landfill. The basic purpose of enzyme use is to enforce the biodecomposition of organic constituents, as well as to reduce nitrogen content. A laboratory-scale sequencing batch (bio)reactor (SBR) was used for the examination of enzymatic application. The effect of different operation strategies on the efficiency of this biological treatment process was studied to optimize performance, especially for the removal of nitrogen compounds and of biodegradable organic matter. It was found that the enzymatic process was able to remove organic matter effectively (expressed as BOD5 and COD) and nitrogen content, color and turbidity.

Biodegradation, Environmental↗
PubMed2000

Physiology of pregnancy and nutrient metabolism.

Pregnancy consists of a series of small, continuous physiologic adjustments that affect the metabolism of all nutrients. The adjustments undoubtedly vary widely from woman to woman depending on her prepregnancy nutrition, genetic determinants of fetal size, and maternal lifestyle behavior. Studies of protein and energy metabolism illustrate the potential of adjusting the use of those nutrients to conserve a fetal supply. Adjustments in the metabolism of nitrogenous compounds are in place by the second quarter of pregnancy. During the last quarter of pregnancy, when fetal demands are greatest, those adjustments allow a positive nitrogen retention. The energy requirement of basal metabolism is influenced by maternal prepregnant nutrition and by fetal size. If maternal energy reserves are low at conception, the basal metabolic rate is down-regulated to conserve energy. Also, women having larger babies tend to have greater increases in their basal metabolic rate and lower rates of maternal energy storage. Changes in maternal food and physical activity behaviors during gestation may augment the physiologic adjustments. However, the substantial variability in food intakes and physical activity makes it difficult to show those changes. Thresholds in the capacity to adjust nutrient use to the amount supplied exist for all nutrients. When intakes fall below the threshold, fetal growth and development is affected more than is maternal health. Efforts to achieve good maternal nutritional status preconception as well as throughout gestation best assure a good milieu for fetal growth and development.

Dietary Proteins↗
PubMed1997

Nitrogen GATA factors participate in transcriptional regulation of vacuolar protease genes in Saccharomyces cerevisiae.

The expression of most nitrogen catabolic genes in Saccharomyces cerevisiae is regulated at the level of transcription in response to the quality of nitrogen source available. This regulation is accomplished through four GATA-family transcription factors: two positively acting factors capable of transcriptional activation (Gln3p and Gat1p) and two negatively acting factors capable of down-regulating Gln3p- and/or Gat1p-dependent transcription (Dal80p and Deh1p). Current understanding of nitrogen-responsive transcriptional regulation is the result of extensive analysis of genes required for the catabolism of small molecules, e.g., amino acids, allantoin, or ammonia. However, cells contain another, equally important source of nitrogen, intracellular protein, which undergoes rapid turnover during special circumstances such as entry into stationary phase, and during sporulation. Here we show that the expression of some (CPS1, PEP4, PRB1, and LAP4) but not all (PRC1) vacuolar protease genes is nitrogen catabolite repression sensitive and is regulated by the GATA-family proteins Gln3p, Gat1p, and Dal80p. These observations extend the global participation of GATA-family transcription factors to include not only well-studied genes associated with the catabolism of small nitrogenous compounds but also genes whose products are responsible for the turnover of intracellular macromolecules. They also point to the usefulness of considering control of the nitrogen-responsive GATA factors when studying the regulation of the protein turnover machinery.

DNA-Binding Proteins↗
PubMed2000

Nitrogen partitioning in Heterorhabditis bacteriophora-infected hosts and the effects of nitrogen on attraction/repulsion.

Entomopathogenic nematode behavior is affected by the condition of their infected hosts. We hypothesized that nitrogen compounds released from infected hosts may be one factor affecting entomopathogenic nematode host-finding and infection behaviors. Our objectives were to (1) investigate the partitioning of nitrogen in Galleria mellonella (L.) infected by Heterorhabditis bacteriophora Poinar and (2) determine attraction and repulsion of H. bacteriophora to various quantities of nitrogen (ammonia). Volatile (ammonia), organic, and inorganic nitrogen forms were monitored during the course of infection. Approximately 0.052 mg of nitrogen was released from a single infected host as volatile ammonia. Most of the ammonia release was detected within the first 3 days postinoculation. Organic nitrogen increased during the course of infection, whereas inorganic nitrogen decreased. The net nitrogen change in the infected host consisted of a loss of approximately 47 mg, most of which was lost within the 1st week of infection. Accelerated loss of nitrogen early in the infection process was likely correlated with activity and growth of bacterial symbionts. Increased organic nitrogen was likely associated with nematode reproduction within the host. Attraction or repulsion of H. bacteriophora to nitrogen (ammonium hydroxide) was measured on agar quadrant plates. Nematodes were attracted to 16 and 160 microg of nitrogen and repelled by concentrations of 1600 and 8000 microg. Our data indicate that nitrogen released from H. bacteriophora-infected hosts attracts nematodes at lower levels (early in the infection) and repels them at higher concentrations (later in the infection process).

Animals↗
PubMed2001

Quantum chemical calculations of infrared spectra for the identification of unknown compounds by GC/FTIR/MS in exobiological simulation experiments.

Gas chromatography/Fourier transform IR spectroscopy/mass spectrometry (GC/FTIR/MS) is a powerful tool for the separation and unambiguous identification of complex mixtures of organic compounds, where the use of two kinds of spectra allows to significantly increase identification reliability. The simplest situation is when acquired spectra can be found in IR and MS databases, or appropriate standards are available; but this is not always the case. Some simulation experiments related to the origins of life and exobiology (e.g., simulation of amino acid pyrolysis during atmospheric entry of space bodies) can be a typical example when one encounters with numerous unknown compounds. To assist their identification by GC/FTIR/MS, recently we suggested quantum chemical calculations of infrared spectra in order to compare them to IR spectra acquired experimentally. The present work summarizes the results obtained by semi-empirical and ab initio methods, discusses their advantages and limitations, considering as test compounds some cyclic amides and amidines derived from amino acids, saturated and unsaturated nitriles (including those of interest for the Titan atmospheric chemistry), acetylenes and some other nitrogen compounds.

Amino Acids↗
PubMedDate not supplied

Study of changes of properties in thermically and hydrothermically treated feeds. 2. N fractions in fermentation medium at the incubation of treated feeds under in vitro conditions.

In the extensive experiments in vitro degradation ability of hydrothermically and thermically treated feeds have been studied. The feeds used were soybean meal, horse bean, alfalfa meal, field pea. The feeds have been treated at 90, 110 and 130 degrees C for 30, 60 and 90 min. The treated feeds have been tested both for microbial degradation ability due to rumen microflora and enzymatic degradation ability via pepsin and trypsin. The fact has been regarded as an important finding that the degradation ability of nitrogenous compounds had been restricted effectively by hydrothermic treatment that was manifested by low ammonia-N levels in fermentation medium (11.3; 8.8; 15.9 and 1.1% out of nitrogen contents in the different feeds). On the other hand improved protein enzymatic digestibility have been recorded in treated feeds as compared with native ones.

Animal Feed↗
PubMedDate not supplied

[Physiological and agrochemical properties of different symbiotic genotypes of pea (Pisum sativum L.)].

Physiological characters of symbiotic mutants of pea were studied: nodulation, activities of nitrogenase and nitrate reductase, chlorophyll content in leaves and their water-holding capacity, biomass accumulation, and nitrogen forms. The parameters reflecting the genotype state of the macrosymbiont under soil conditions considerably varied. Supernodulation mutants stood out against symbiotic pea genotypes by high contents of chlorophyll and nonprotein nitrogen compounds, high nitrogenase activity, and low nitrate reductase activity. The efficiency of the legume-rhizobium symbiosis was largely mediated by the macrosymbiont genotype. The highest atmospheric nitrogen fixation (50-80%) was observed in the parental pea varieties. Despite the highest nitrogenase activity in the nodules, the supernodulation mutants were inferior to the parental varieties by the nitrogen fixation capacity (40-60%), which was due to their low productivity.

Genotype↗
PubMed1981

Physiological studies on Phymatotrichum omnivorum. XII Influence of cultural conditions on amylase synthesis.

The production of extracellular amylase by P. omnivorum has been studied under different cultural conditions. Maximum mycelial growth and amylase synthesis were found in basal synthetic medium containing 2% glycogen as the carbon source. Significant amounts of amylase and growth were obtained in medium containing other carbon compounds with alpha-1, 4-linkages. Optimum temperatures for mycelial growth and amylase synthesis were found at 28 degree and 30 degree C, respectively. Of all the nitrogenous compounds tested, ammonium nitrate supported the maximum mycelial growth and amylase production. Increasing the concentration of starch in the basal medium increased the growth as well as the enzyme synthesis.

Amylases↗
PubMed2006

Fixation of nitrogen in an electrospray mass spectrometer.

The formation of an iron-nitrogen compound in an electrospray ionization instrument is reported. The iron was released from the stainless steel electrospray needle by acetic acid added to displace trifluoroacetic acid and the nitrogen was present as the drying gas. The product is an iron nitride ion, [N(2)FeOH](1+), m/z 100.9438, and is capable of addition to peptides and proteins.

Acetic Acid↗