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PubMed1981

[Experimental study of the dynamics in the biochemical parameter changes in the oxytetracycline biosynthesis process in apparatus of varying capacity].

An increase in the input of the mechanical power speeds up the culture growth, which correlates with the rate of carbohydrate and nitrogen consumption during the first phase of the process, the time of the biosynthesis phase onset and the level of the antibiotic production during this phase. During the second half of the process the antibiotic biosynthesis markedly decreases, especially in the apparatus with a high input of the mechanical power. Deficiency in carbon and nitrogen is one of the causes of this decrease. The activity level at the end of the biosynthesis in such apparatus does not differ significantly, since it depends on the biosynthesis rate during the whole cultivation period.

Carbohydrate Metabolism↗
PubMed2005

Impacts of population growth and economic development on the nitrogen cycle in Asia.

Asia is the major consumer of fertilizer nitrogen and energy in the world, and consequently shares a considerable proportion of the world creation of reactive nitrogen (Nr). However, if estimated on per capita basis, Asia is characterized by a lower arable land area, fertilizer nitrogen consumption, energy consumption, and gross domestic product, as well as lower daily protein intake. To meet the increasing needs for food and energy for the growing population combined with the improvement of living standards, Nr will inevitably increase. The present study estimates the creation of Nr and the emissions of various N compounds into environment in Asia currently and in 2030. In comparison with the world averages, the lower fertilizer nitrogen and energy use efficiencies, and the lower use of animal wastes for agriculture imply that there is potential for moderating the increase in Nr and its impacts on the environment. Strategies for moderating the increase are discussed.

Animals↗
PubMed2003

Interactions between irradiance and nutrient availability during astaxanthin accumulation and degradation in Haematococcus pluvialis.

Fully synchronised germination of Haematococcus pluvialis astaxanthin-replete aplanospores was induced by transfer to nitrogen-sufficient conditions under either high or low light intensities, and growth, pigment content and nitrogen consumption were monitored during the cell cycle. No germination of the aplanospores was achieved in the absence of nitrate, even when cells were transferred at low light intensities. On the other hand, cell density and chlorophyll concentration increased dramatically and astaxanthin concentration decreased in N-sufficient cultures due to the germination of 100% of the aplanospores, as demonstrated by flow cytometry. No significant effect of light intensity was observed on the degradation of astaxanthin during germination. In germinated cultures, nitrogen was depleted more rapidly under high light conditions, which resulted in earlier entry into the aplanospore stage and accumulation of astaxanthin. Germination of aplanospores accompanied by astaxanthin degradation could also be obtained in the dark in nutrient-sufficient conditions although at a much lower efficiency. The results demonstrate that nutrient availability is the main factor controlling the transition between red and green stages of H. pluvialis, with astaxanthin being accumulated only when cell division has ceased. High light levels accelerate the process by increasing the rate of nutrient depletion and providing more energy for astaxanthin synthesis.

Chlorophyll↗
PubMed2004

Encapsulation of brewers yeast in chitosan coated carrageenan microspheres by emulsification/thermal gelation.

Brewers yeast was encapsulated in kappa-carrageenan microspheres using an emulsification-thermal gelation approach. Due to heat sensitivity of the yeast at temperatures in excess of 36 degrees C, mixtures of low and high gelation temperature carrageenans were tested to obtain a blend yielding a gelation temperature under 40 degrees C. A 20:80 dispersion of 2% carrageenan sol containing cells, in warm canola oil, produced microspheres upon cooling, with a mean diameter of 450 microm and narrow size dispersion (span of 1.2). Application of a chitosan membrane coat to minimize cell release, increased the mean microsphere diameter to 700 microm, due to the coat thickness and swelling of the microspheres. This diameter was designed so as to minimize mass transfer limitations. Batch fermentations were carried out in a 3 L reactor on a commercial wort medium. Cell loading was 10(7) cells mL(-1) microspheres, and cell "burst" release was observed upon inoculation into fresh medium, whether microspheres were coated or not. The kinetics of intra- and extracapsular cell growth were determined. Increased concentrations of extracapsular free cells could be accounted for by growth in the wort medium, and by ongoing release from the gel microspheres, whether coated or not. Cell release from chitosan-coated carrageenan microspheres was less than that from uncoated microspheres, likely due to retention by the membrane coat. Growth kinetics and alpha-amino nitrogen consumption of encapsulated yeast were higher than that of free cells, and differences in alcohol and ester profiles were also observed, likely due to modified metabolism of the encapsulated yeast.

Alcohols↗
PubMed2004

The anammoxosome: an intracytoplasmic compartment in anammox bacteria.

Anammox bacteria belong to the phylum Planctomycetes and perform anaerobic ammonium oxidation (anammox); they oxidize ammonium with nitrite as the electron acceptor to yield dinitrogen gas. The anammox reaction takes place inside the anammoxosome: an intracytoplasmic compartment bounded by a single ladderane lipid-containing membrane. The anammox bacteria, first found in a wastewater treatment plant in The Netherlands, have the potential to remove ammonium from wastewater without the addition of organic carbon. Very recently anammox bacteria were also discovered in the Black Sea where they are responsible for 30-50% of the nitrogen consumption. This review will introduce different forms of intracytoplasmic membrane systems found in prokaryotes and discuss the compartmentalization in anammox bacteria and its possible functional relation to catabolism and energy transduction.

Anaerobiosis↗
PubMed2001

Ion chromatographic analysis of selected free amino acids and cations to investigate the change of nitrogen metabolism by herbicide stress in soybean (glycine max).

A simple and reliable method for the determination of NH4+, K+, Na+, aspartic acid, asparagine, glutamine, and alanine by ion chromatography has been developed. It is suitable for monitoring changes of nitrogen metabolism in soybean because it can accurately measure concentrations o asparagine and NH4+, two key substances for nitrogen storage and transport in this plant species Analysis of asparagine distribution in soybean indicated that higher levels (up to 18.4 micromol g(-1) of fresh mass) occur in stems and lower levels in roots (2.0 micromol g(-1) of fresh mass) and leaves (1.6 micromol g(-1) of fresh mass). When the herbicide metsulfuron-methyl (0.5, 5, and 50 ppb) was applied via the nutrient solution to the root system, asparagine concentrations increased 3-6 times in stems roots, and leaves. Metsulfuron-methyl is known to impair the synthesis of branched amino acids and, in consequence, protein synthesis. Thus, nitrogen consumption was limited, leading to ar accumulation of asparagine. The possible use of this physiological response in agricultural practice to identify herbicide stress in soybean and to detect low-level residues of sulfonylurea herbicides ir the soil is discussed.

Alanine↗
PubMed2003

[Effect of prescribed burning on grassland nitrogen gross mineralization and nitrification].

The seasonal dynamics of nitrogen gross mineralization, nitrification, and mineral nitrogen consumption rates in burned and unburned Leymus chinensis grasslands were studied with 15N pool dilution technique. The results indicated that the gross mineralization and nitrification rates in burned area were higher than those in unburned area in April and May, and lower than those in unburned area in September. NH4(+)-N consumption rates were higher than unburned area in April and May, and lower in September. NO3(-)-N consumption rates were higher than control in April and May, and lower than control in July and September. The NH4(+)-N concentrations were higher in burned area in April, May and July, and no difference in September. NO3(-)-N concentrations were no difference between burned and unburned areas in April and May, and higher in burned areas in July and September.

Ammonia↗
PubMed1999

Effects of increasing ruminally degraded nitrogen and abomasal casein infusion on net portal flux of nutrients in yearling heifers consuming a high-grain diet.

Seven Meat Animal Research Center (MARC) III heifers (410+/-25 kg) fitted with hepatic portal, mesenteric venous, carotid catheters, and an abomasal cannula were used in a 7 x 5 incomplete Latin square design experiment. The objective was to evaluate the effects of increasing levels of ruminally degradable N (RDN) with or without the addition of abomasally infused casein on portal-drained visceral (PDV) flux of nutrients. Treatments consisted of dietary CP percentage levels of 9.5 (control), control plus .72% dietary urea (11.5U), control plus 1.44% dietary urea (13.5U), control plus abomasally infused casein (250 g/d; 11.5C), or control plus .72% dietary urea and abomasally infused casein (250 g/d; 13.5UC). All diets contained (DM basis) 80% ground corn, 15% corn silage, and 5% dry supplement and were provided for ad libitum consumption. Nitrogen intake increased (linear, P < .001) as CP increased from 9.5 to 13.5%. Portal-drained visceral release of ammonia N increased (linear, P < .10) as RDN increased, and was greater (P < .05) when protein was fed compared with heifers fed control (P < .10). Urea N removal by PDV was not affected ( P > . 10) by level of RDN but was greatest when 11.5C was fed and least when 13.5UC was fed. Net alpha-amino N (AAN) release by PDV was greatest when 13.5UC was fed (309 mmol/h), least when 9.5% CP was fed (112 mmol/h), and intermediate for the other groups (205 to 252 mmol/h). These data suggest that removal of N by the PDV may promote microbial protein synthesis when dietary RDN is low. When RDN needs have been met and amino acids are deficient for the host, escape protein should be fed to increase amino acid absorption.

Abomasum↗
PubMed1975

Enniatin production by Fusarium sambucinum: primary, secondary, and unitary metabolism.

Fusarium sambucinum liquid surface cultures on semi-defined medium with glucose as carbon source passed through well-defined phases corresponding to trophophase, idiophase (enniatin production), and a degenerative phase. All the glucose was consumed by day 6, at which time the mycelial dry weight had reached only half its maximum. When glucose was replaced by lactose, there was no separation of trophophase and idiophase. Enniatin production, dry weight, and sugar and nitrogen consumption were in approximate balance throughout the growth period (25 days), after which slow degeneration began. The term 'unitary metabolism' is proposed for this type of unphased behaviour. Unitary metabolism may approximate more closely to that occurring under natural conditions than does the metabolic phase separation observed when rapidly utilized carbon sources are used in laboratory cultures.

Anti-Bacterial Agents↗
PubMed1996

Screening of microorganisms for biodegradation of poly(lactic-acid) and lactic acid-containing polymers.

The ability of some microorganisms to use lactic acid stereocopolymers and copolymers with glycolic acid as sole carbon and energy sources was studied under controlled or natural conditions. First, 14 filamentous fungal strains were tested in liquid cultures, adopting total lactic acid consumption, nitrogen source exhaustion, and maximal biomass production as selection criteria. Two strains of Fusarium moniliforme and one strain of Penicillium roqueforti were able to totally assimilate DL-lactic acid, partially soluble racemic oligomers (MW = 1,000), and the nitrogen source. Only one strain of F. moniliforme was able to grow on a poly(lactic acid)-glycolic acid copolymer (MW = 150,000) after 2 months of incubation at 28 degrees C on synthetic agar medium. Mycelium development was examined by scanning electron microscopy. F. moniliforme filaments were observed to grow not only at the copolymer surface but also through the bulk of the copolymer. In a second approach, plates made of a racemic poly(lactic acid) were buried in the soil before being incubated in petri dishes containing mineral agar medium under controlled conditions. Five strains of different filamentous fungi were isolated, and their ability to assimilate racemic poly(lactic acid) oligomers was tested in liquid cultures.

Biodegradation, Environmental↗
PubMed1999

Microprocessor-controlled freezing device for cryopreservation of cell samples.

A freezing device for cryopreservation of blood mononuclear cells has been developed. The device is microcontroller operated, allowing cell freezing by a fully automatic, unattended process. To ensure optimum preservation, the temperature in the cell suspension uniformly decreases from room temperature to -100 degrees C and then the samples are transferred to long-term storage. The performance of the device has been tested using both physiological solution and a sample of cell suspension. The control of temperature variation of cell suspension in the entire temperature range has been realised with an accuracy better than +/- 0.1%. The viability of cells recovered from the frozen samples was 95%. The nitrogen consumption for one cycle of cryopreservation was 1.51. In addition to the fully automatic mode, the manual and semi-automatic modes are available for research purposes. The device has been designed using low cost and widely used electronic components and materials, it is compact and simple to operate.

Algorithms↗
PubMedDate not supplied

[Energy metabolism and metabolite flow from muscle tissue during TPN of trauma patients].

AIM: We evaluated muscle-visceral interorgan flux of substrates in 8 critically ill patients in the flow phase after injury. SETTING: This study was conducted on critically ill patients admitted in ICU. PATIENTS: 8 patients were studied immediately after injury. RESULTS: We measured leg flux for oxygen, amino acids, glucose, lactate pyruvate, keton bodies, free fatty acids (FFA), free and total carnitine, and whole body oxygen consumption, nitrogen (N) balance and 3-methyl hystidine (3MEH) excretion during fasting and the second day of metabolic treatment (10.7 +/- 0.06 g x N x m-2 e 1035.5 +/- 3.9 kcal x m-2 x die). During fast the leg shows a net release of N, pyruvate, FFA and free carnitine while glucose, lactate and keton bodies fluxes are not different from zero. The energy balance of the leg is markedly negative (substrate for 79 kcal x m-2 burned for leg energy requirement and 347 kcal x m-2 released as a such). Assuming the body muscle tissue 4.5 times the leg tissue and knowing whole body energy balance, we were able to assess that the non muscular (visceral) part of the body resulted in a consistently positive energy balance. The metabolic treatment is able to match the energy expenditure and the substrate efflux of the leg (and the whole body muscle tissue). In fact the efflux of amino acids and FFA is reduced pyruvate blunted while glucose is remarkably taken up (the uptake of the whole muscle tissue accounted for 72% of the daily load). At the same time, the treatment blunts leg free carnitine and reduces body 3MEH output. Moreover, the caloric balance of the non muscular part of the body remains positive even if the qualiquantitative uptake of substrates is different from fasting. CONCLUSION: Substrates for energy requirements of visceral tissue came from muscular tissue. The metabolic treatment is able to modulate this process.

Energy Metabolism↗
PubMed1987

Nitrogen narcosis and alcohol consumption--a scuba diving fatality.

Nitrogen narcosis can cause death among experienced scuba divers. Nitrogen under pressure affects the brain by acting as an anesthetic agent. Furthermore, the consumption of ethanol along with diving will cause the symptoms of nitrogen narcosis to occur at depths less than 30 m. Our case deals with an experienced diver who drank alcoholic beverages before diving and developed symptoms of nitrogen narcosis at a shallow depth. These two conditions contributed to his death by drowning.

Adult↗
PubMed1993

Cereals, nitrogen and population: an assessment of the global trends.

In the lecture following the award of his Nobel Prize for Peace in 1970 the eminent agronomist Norman Borlaug remarked: 'If you desire peace, cultivate justice but at the same time cultivate the fields to produce more bread'. This is as true now as it was then. This article analyses trends in the relationship between cereal production and nitrogen fertilizer consumption up to the year 2030. It concludes that a doubling of chemical nitrogen consumption over this period is necessary to maintain world cereal production per capita at its present level.

Agriculture↗
PubMed1997

Effect of stanozolol on body composition, nitrogen balance, and food consumption in castrated dogs with chronic renal failure.

OBJECTIVE: To determine the effect of stanozolol on body composition, nitrogen balance, and food consumption in castrated dogs with chronic renal failure. DESIGN: Blinded crossover trial. ANIMALS: 22 castrated Beagles with experimentally induced chronic renal failure. PROCEDURE: Dogs were divided into 2 groups of 11 dogs each. During each of two 6-week treatment periods, dogs in 1 group received stanozolol, and those in the other group received a control agent. Nitrogen balance, body composition, and food consumption were determined. RESULTS: During administration of stanozolol, the amount of food consumed per dog, lean body mass, and nitrogen balance increased. Stanozolol did not have a significant effect on body fat, bone mineral content, or food consumption per kilogram of body weight. CLINICAL IMPLICATIONS: For dogs with mild-to-moderate, nonuremic, experimentally induced, chronic renal failure, stanozolol had positive effects on nitrogen balance and lean body mass.

Anabolic Agents↗