Nitrogen source

Resting cells of P. freudenreichii under both aerobic and anaerobic conditions rapidly degraded aspartic acid, glycine and alanine, and more slowly other amino acids. But large strain and species variations were observed, and certain specificities in the metabolism of different amino acids were found (Langsrud et al, 1995). 

In the presence of all amino acids in the medium bacterial growth is facilitated, since amino acids are incorporated into proteins in a readily available form. Preparation methods of casein hydrolysate were found to have important effects on propionibacterial growth. Mixtures of amino acids produced by alkaline, acid and trypsin hydrolysis were tested (Zodrow et al., 1963a) and the best result was achieved with the trypsin hydrolysate. It was suggested that in this case tryptophane is preserved and some peptides are formed which have specific stimulatory effects on the bacterial growth. Nitrate inhibits the deamination of amino acids in cheese by propionic acid bacteria (Peltola and Antila, 1953). 

Nitrate reduction. According to Kaspar (1982), P. acidipropionici, P. freudenreichii, P. jensenii, P. shermanii and P. thoenii can reduce nitrate to nitrite and further to N2O. Formation of N2O from nitrite in prokaryotes may represent a mechanism of detoxification rather than transformation of energy. N2O was not further reduced oxygen inhibited nitrate reduction by P. acidipropionici and P. thoenii. The enzymes of nitrate and nitrite reduction were either constitutive or derepressed in anaerobiosis only P. pentosaceum contained a constitutive nitrate reductase. Nitrate stimulated the synthesis of nitrate reductase in P. acidipropionici, specific growth rates and biomass yields were increased by the addition of nitrate. Nitrite at a concentration of 10 mM was not inhibitory. 

The ability to reduce nitrate was investigated by Swart et al. (1995) and was shown to vary from species to species and from strain to strain, being strongly affected by environmental factors. P. acidipropionici, P. acnes and P. freudenreichii subsp. freudenreichii were able to reduce nitrate, in contrast with P. jensenii and P. thoenii that were unable to do so in yeast 

Test substrate Carbon source in growth medium  

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As constituents of proteins the amino-acids are important constituents of the food of animals. Certain amino-acids can be made in the body from ammonia and non-nitrogenous sources others can be made from other amino-acids, e.g. tyrosine from phenylalanine and cystine from methionine, but many are essential ingredients of the diet. The list of essential amino-acids depends partly on the species. See also peptides and proteins. 

Regulations specify a considerable Hst of additives and treatments which may be permitted under controlled limits and conditions. It is important to note that no wine receives mote than a few of these treatments, and many have none. For example, most grape musts ferment readily without additions, but some extra nitrogen source for the yeasts is occasionally beneficial. If some is requited, ammonium phosphate is the most commonly used. 

Urea Process. In a further modification of the fundamental Raschig process, urea (qv) can be used in place of ammonia as the nitrogen source (114—116). This process has been operated commercially. Its principal advantage is low investment because the equipment is relatively simple. For low production levels, this process could be the most economical one. With the rapid growth in hydrazine production and increasing plant size, the urea process has lost importance, although it is reportedly being used, for example, in the People s RepubHc of China (PRC). 

Fig. 8. Transient NO emissions at synthetic wastes nitrogen contents of (D), 1% ( ), 3% and (0)> 10%, where the % of O2 is 2ero. Aniline is used as a nitrogen source and toluene is used to keep the total hydrocarbon weight fixed at 35 g (29).

Gate oxide dielectrics are a cmcial element in the down-scaling of n- and -channel metal-oxide semiconductor field-effect transistors (MOSEETs) in CMOS technology. Ultrathin dielectric films are required, and the 12.0-nm thick layers are expected to shrink to 6.0 nm by the year 2000 (2). Gate dielectrics have been made by growing thermal oxides, whereas development has turned to the use of oxide/nitride/oxide (ONO) sandwich stmctures, or to oxynitrides, SiO N. Oxynitrides are formed by growing thermal oxides in the presence of a nitrogen source such as ammonia or nitrous oxide, N2O. Oxidation and nitridation are also performed in rapid thermal processors (RTP), which reduce the temperature exposure of a substrate. 

Although the natural abundance of nitrogen-15 [14390-96-6] leads to lower sensitivity than for carbon-13, this nucleus has attracted considerable interest in the area of polypeptide and protein stmcture deterrnination. Uniform enrichment of is achieved by growing protein synthesi2ing cells in media where is the only nitrogen source. reverse shift correlation via double quantum coherence permits the... 

Semifermentation Process. In this process, the metaboHc intermediate in the amino acid biosynthesis or the precursor thereof is added to the medium, which contains carbon and nitrogen sources, and other nutrients required for growth and production, and the metaboHte is converted to the... 

Economic Aspects and Uses. Ammonium chloride is used as a nitrogen source for fertilization of rice, wheat, and other crops ia Japan, China, India, and Southeast Asia. Japan is a large producer, much of which is as by-product. 

Sodium is an indispensable element for some crops (notably sugar beet), can partially substitute for potassium in several crops, contributes to neutralising soil and subsoil acidity, and has a positive effect on soil phosphoms solubiUty. Sodium is an essential nutrient for cattle, and sodium appHcation to soil increases its content in pastures. Sodium nitrate is particularly effective as a nitrogen source for sugar beet, vegetable crops, tobacco, and cotton (qv), and for any crop in acid soils. 

High nitrogen content distinguishes it from other controlled release nitrogen sources. 

Oxamide is produced commercially by Ube Industries, Ltd. (Japan) and a pilot process is being operated by Enichem (Italy). It is not produced domestically as a commercial fertilizer, although it was the subject of much research and development activity by the Tennessee Valley Authority s (TVA) National Fertilizer Research and Development Center. It is made in small quantities for industrial use by AUied Chemical, Hummel Chemical Co., and United Guardian, Inc. Oxamide has appHcation as a controlled release nitrogen source for the turf and specialty agricultural markets. 

Dithiolylium salts (483) may be converted into pyrazoles, pyrazolium salts and isothiazoles depending on the type and degree of substitution of the nitrogen source. 

Plant and animal cells have numerous chromosomes. Growth rates are relatively slow. A typical nutrient medium will contain a large number of vitamins and growth factors in addition to complex nitrogen sources, because other specialized cells in the original structures supply these needs. A plant or animal cell is not hke a microbial cell in its ability to function independently. 

A. 2-(Trimethtjlsiloxymethyl)allyltvimethylBilane. An oven-dried (Note 1) 2-L, three-necked, round-bottomed flask is equipped with an air-tight mechanical stirrer (Note 2), a 500-mL pressure-equalizing dropping funnel (Note 3), and a reflux condenser. The top of the condenser is connected to a three-way stopcock with one branch connected to a nitrogen source and the other to a variable pressure oil pump with a dry-ice trap (Note 4). The apparatus is flamed dry under a steady stream of nitrogen. The flask is... 

Other PK variations include microwave conditions, solid-phase synthesis, and the fixation of atmospheric nitrogen as the nitrogen source (27—>28). Hexamethyldisilazane (HMDS) is also an excellent ammonia equivalent in the PK synthesis. For example, 2,5-hexanedione and HMDS on alumina gives 2,5-dimethylpyrrole in 81% yield at room temperature. Ammonium formate can be used as a nitrogen source in the PK synthesis of pyrroles from l,4-diaryl-2-butene-l,4-diones under Pd-catalyzed transfer hydrogenation conditions. 

The close relationship of this reaction scheme with that for the Hantzsch protocol becomes obvious upon careful examination. The use of AcOH/NRtOAc as the solvent/nitrogen source has dramatically improved on the experimental ease and yield of this reaction. ... 

The previous methods used commercial microwave ovens. When a Smith Synthesizer was employed where one could control temperature and pressure, further improvements in time and yield were noted for the conversion of 95 and 82 into 96. Optimal conditions included the use of aqueous ammonium hydroxide as solvent and nitrogen source. The method was efficient enough to execute on a 4 x 6 array using the dicarbonyl and the aldehyde as points of diversity. The library of 24 compounds was obtained in 39-89% yields and 53-99% purity. 

The yield was highest with starch or dextrin, intermediate and about the same with sucrose, glucose, maltose and lactose and poorest with glycerol. Kanamycin was produced by media containing soybean meal, peanut meal, cottonseed meal, corn steep liquor, peptone, yeast extract or meat extract, with or without sodium nitrate. Commercially available soybean meal was recognized to be one of the best nitrogen sources. The addition of corn steep liquor, peptone, yeast extract or nitrate to the soybean meal promoted the production of kanamycin. 

Nitrogen sources include proteins, such as casein, zein, lactalbumin protein hydrolyzates such proteoses, peptones, peptides, and commercially available materials, such as N-Z Amine which is understood to be a casein hydrolyzate also corn steep liquor, soybean meal, gluten, cottonseed meal, fish meal, meat extracts, stick liquor, liver cake, yeast extracts and distillers solubles amino acids, urea, ammonium and nitrate salts. Such inorganic elements as sodium, potassium, calcium and magnesium and chlorides, sulfates, phosphates and combinations of these anions and cations in the form of mineral salts may be advantageously used in the fermentation. 

The metal catalyst is not absolutely required for the aziridination reaction, and other positive nitrogen sources may also be used. After some years of optimization of the reactions of alkenes with positive nitrogen sources in the presence of bromine equivalents, Sharpless et al. reported the utility of chloramine-T in alkene aziridinations [24]. Electron-rich or electron-neutral alkenes react with the anhydrous chloramines and phenyltrimethylammonium tribromide in acetonitrile at ambient temperature, with allylic alcohols being particularly good substrates for the reaction (Schemes 4.18 and 4.19). 

Guanidines have been shown to act as nitrogen sources in the conversion of... 

Despite the effectiveness of chloramine-T in this new method, removal of the toluenesulfonyl group from the newly introduced nitrogen substituent requires harsh conditions. The finding that the N-chloramine salt of tert-butylsulfonamide is also an efficient nitrogen source and the terminal oxidant for aziridination of... 

A bacterium is grown aerobically with glucose as sole source of carbon and ammonium ions as nitrogen source. Experimental analysis shows that six moles of glucose are utilised for each mole of biomass produced. Write the reaction equation for growth if the elemental composition of the cells is CHi,666 CW Nojd. 

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