A comparative study of the ability of organic nitrogenous compounds to serve as sole sources of nitrogen for the growth of plants

Summary The ability of over 160 organic nitrogen compounds to serve as sole sources of nitrogen for the growth in sterile culture ofNeurospora crassa, Chlorella vulgaris andSpirodela oligorrhiza has been tested. With some forms of organic nitrogen all three organisms grew as well as with the more usual inorganic forms. Neurospora had the ability to use a wider range of compounds than the other organisms. Some compounds, including a few native to the organism inhibited Spirodela.     

Effect of yeast extract and succinic acid on growth and sporulation of alternaria species

Summary Alternaria solani andA. nyctanthi, these pathogens causing leafspot disease were able to metabolize a variety of nitrogen compounds when grown on different culture media. The amount of growth varied with the nitrogen source. Peptone produced the best zonation when added in definite proportion to the yeast extract medium. Ammonium compounds were found to be moderately effective for growth but poor for sporulation. The effect of adding succinic acid in media containing ammonium sources and the role of pH in the utilization of nitrite nitrogen was investigated.The fungus gave more vegetative growth on a mixture of aminoacids than in culture media in which the same amino acids were supplied singly to study the effect produced on growth and sporulation.     

A survey of available nitrogen sources for the growth of the blue-green alga,Agmenellum quadruplicatum

The growth response of the marine blue-green alga, Agmenellum quadruplicatum to 60 inorganic and organic nitrogen sources was studied. These compounds were offered as sole nitrogen sources. Most amino acids, most purines, and urea were good nitrogen sources for growth.     

Growth response of four freshwater algal species to dissolved organic nitrogen of different concentration and complexity

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Growth and physiological responses of <Emphasis Type="Italic">Picea asperata</Emphasis> seedlings to elevated temperature and to nitrogen fertilization

Picea asperata is a dominant species in the subalpine coniferous forests distributed in eastern edges of Tibetan Plateau and upper reaches of the Yangtze River. The paper mainly identified the short-term influences of experimental warming, nitrogen fertilization, and their combination on growth and physiological performances of Picea asperata seedlings. These seedlings were subjected to two levels of temperature (ambient; infrared heater warming) and two nitrogen levels (0; 25 g m⁻² a⁻¹ N) for 6 months. We used a free air temperature increase of overhead infrared heater to raise both air and soil temperature by 2.1 and 2.6°C, respectively. The temperature increment induced an obvious enhancement in biomass accumulation and the maximum net photosynthetic rate, and decreased AOS and MDA level under ambient nitrogen conditions. Whereas, negative effects of experimental warming on growth and physiology was observed under nitrogen fertilization condition. On the other hand, nitrogen fertilization significantly improved plant growth in unwarmed plots, by stimulating total biomass, maximum net photosynthetic rate (A _max), antioxidant compounds, as well as reducing the content of AOS and MDA. However, in warmed plots, nitrogen addition clearly decreased A _max, antioxidant compounds, and induced higher accumulation of AOS and MDA. Obviously, the beneficial effects of sole nitrogen on growth and physiology of Picea asperata seedlings could not be magnified by artificial warming.     

Nitrogen regulation of the xyl genes of Pseudomonas putida mt‐2 propagates into a significant effect of nitrate on m‐xylene mineralization in soil

The nitrogen species available in the growth medium are key factors determining expression of xyl genes for biodegradation of aromatic compounds by Pseudomonas putida. Nitrogen compounds are frequently amended to promote degradation at polluted sites, but it remains unknown how regulation observed in the test tube is propagated into actual catabolism of, e.g. m‐xylene in soil, the natural habitat of this bacterium. To address this issue, we have developed a test‐tube‐to‐soil model system that exposes the end‐effects of remediation practices influencing gene expression of P. putida mt‐2. We found that NO₃^? compared with NH₄⁺ had a stimulating effect on xyl gene expression in pure culture as well as in soil, and that this stimulation was translated into increased m‐xylene mineralization in soil. Furthermore, expression analysis of the nitrogen‐regulated genes amtB and gdhA allowed us to monitor nitrogen sensing status in both experimental systems. Hence, for nitrogen sources, regulatory patterns that emerge in soil reflect those observed in liquid cultures. The current study shows how distinct regulatory traits can lead to discrete environmental consequences; and it underpins that attempts to improve bioremediation by nitrogen amendment should integrate knowledge on their effects on growth and on catabolic gene regulation under natural conditions.     

Effect of culture conditions on antifouling compound production of a sponge-associated fungus

Microorganisms associated with invertebrate hosts have long been suggested to be a source for bioactive metabolites. In this study, we reported that a sponge-associated fungus, Letendraea helminthicola, produced two antifouling compounds: 3-methyl-N-(2-phenylethyl) butanamide and cyclo(D-Pro-D-Phe). To optimize the production of these antifouling compounds, we then examined the production of compounds under different culture conditions (temperature, salinity, pH, and carbon and nitrogen sources). This fungus grew well and produced more compounds at temperatures between 18 and 30°C; the fungus grew well at 75 parts per thousand (ppt) salinity but produced the highest amount of antifouling compounds at 30 and 45 ppt. The optimal initial pH value for mycelial growth was 5.5 to 6.5, whereas the production of the antifouling compounds was maximized at pH 3.5 and 4.5. Glucose and xylose (as carbon sources) increased the production of antifouling compounds. Yeast extract and peptone (as nitrogen sources) maximized the production of mycelial biomass and antifouling compounds. Our results indicate that culture conditions greatly affect the production of bioactive compounds from mycelial fungal cultures as exemplified by strain L. helminthicola and that the conditions favorable for fungal growth may not be the best conditions for bioactive compound production.     

Evaluation of alternative nitrogen and carbon sources for sugarbeet suspension culture platings in development of cell selection schemes

Summary Low molecular weight nitrogenous impurity compounds as well as raffinose are negative quality factors that interfere with efficient processing of sugarbeet (Beta vulgaris L.) for sucrose. In order to identify nutrient media for cell selection of biochemical mutants or transgenics that might have reduced levels of these processing impurities, the ability of 10 endogenous compounds to serve as sole nitrogen or carbon source for suspension plating and subculture callus growth was evaluated. The most productive concentrations of nitrate, ammonium, l-glutamine, l-glutamate, urea, and l-proline as sole nitrogen sources supported plating callus growth at 106, 159, 233, 167, 80, and 52%, respectively, as well as the historical 60 mM mix of nitrate and ammonium in Murashige-Skoog medium. Glycine betaine and choline did not support growth. d(+) Raffinose and d(+) galactose supported plating callus growth only 67 and 25%, respectively, as well as sucrose as sole carbohydrate source. No callus growth occurred on glutamine, glutamate, or glycine betaine as the sole carbon or carbon plus nitrogen source. Platings on either nitrate or ammonium as sole nitrogen source did not differ in sensitivity to the nitrate uptake inhibitor phenylglyoxal, suggesting that phenylglyoxal lacks the specificity for use in selection for mutants of nitrate uptake. The ability of raffinose to be used as the carbon source, and glutamine or glutamate as the nitrogen source, may preclude their use for selection of genetic variants accumulating less of these processing impurities. However, mutants or transgenics able to utilize either glutamine, glutamate, or glycine betaine might be selectable on media containing any one of these as carbon, nitrogen, or carbon plus nitrogen source, respectively, that is incapable of supporting wild-type cell growth.     

Interrelated responses of tomato plants and the leaf miner Tuta absoluta to nitrogen supply

Plant–insect interactions are strongly modified by environmental factors. This study evaluates the influence of nitrogen fertilisation on the tomato (Solanum lycopersicum L.) cv. Santa clara and the leafminer (Tuta absoluta (Meyrick), Lepidoptera: Gelechiidae). Greenhouse‐grown tomato plants were fed hydroponically on a complete nutrient solution containing either a high nitrogen concentration (HN) sustaining maximum growth or a low nitrogen concentration (LN) limiting plant growth. Insect‐free plants were compared with plants attacked by T. absoluta. Seven and 14 days after artificial oviposition leading to efficacious hatching and larvae development, we measured total carbon, nitrogen and soluble protein as well as defence compounds (phenolics, glycoalkaloids, polyphenol oxidase activity) in the HN versus LN plants. Only in the HN treatment did T. absoluta infestation slightly impair leaf growth and induce polyphenol oxidase (PPO) activity in the foliage. Neither the concentration of phenolic compounds and proteins nor the distribution of nitrogen within the plant was affected by T. absoluta infestation. In contrast, LN nutrition impaired T. absoluta‐induced PPO activity. It decreased protein and total nitrogen concentration of plant organs and enhanced the accumulation of constitutive phenolics and tomatine. Moreover, LN nutrition impaired T. absoluta development by notably decreasing pupal weight and lengthening the development period from egg to adult. Adjusting the level of nitrogen nutrition may thus be a means of altering the life cycle of T. absoluta. This study provides a comprehensive dataset concerning interrelated responses of tomato plants and T. absoluta to nitrogen nutrition.     

Effect of phosphorus and nitrogen on growth,chlorophyll, amino nitrogen,soluble sugar contents and algal heterocysts of water fernAzolla pinnata

The P uptake inAzolla pinnata in mineral medium increased linearly with increasing phosphate doses and optimum growth and chlorophyll content of fern were recorded at 1.2 mM of K₂HPO₄. The higher doses of phosphate reduced growth and chlorophyll, but an increase in soluble sugar and amino nitrogen was noticed. Addition of combined nitrogen sources decreased the fern growth, soluble sugar, chlorophyll and heterocyst frequency but amino nitrogen was comparatively higher. The growth and chlorophyll content were always high when the fern was grown in the absence of added nitrogen sources; this supports the thesis about the specific importance of symbiosis for the nutrition of fern with nitrogen which cannot be replaced by mineral compounds.     

Effect of nitrogen source on biosynthesis of rapamycin by Streptomyces hygroscopicus

Six non-amino acid nitrogen compounds were examined as nitrogen source for growth of Streptomyces hygroscopicus and biosynthesis of rapamycin. Of the nitrogen sources studied, ammonium sulfate was the best with respect to formation of rapamycin, and supported cell growth comparable to the organic nitrogen sources used in the control chemically defined medium, ie, aspartate, arginine plus histidine. In the new chemically defined medium, which is buffered with 200 mM 2-(N-morpholino)ethanesulfonic acid to prevent decline of pH during fermentation, an ammonium sulfate concentration of 40 mM was optimal for biosynthesis of rapamycin. Rapamycin production increased by more than 30% on both volumetric and specific bases as compared to the previous medium containing the three amino acids as nitrogen source. Received 08 November 1996/ Accepted in revised form 07 April 1997     

Physiological and biochemical contributions to the taxonomy of the genus Prototheca

Prototheca zopfii (12 strains) is able to use glucose, fructose, propanol, glycerol, and acetate as sources of carbon for growth. One of the strains is biochemically (utilization also of galactose and mannose), and two strains are morphologically slightly different.Two strains can be identified as P. wikerhamii. They exhibit good growth with glucose, fructose, galactose, trehalose, propanol, glycerol, acetate, and glutamate as sources of carbon. P. spec. 263-2 grows only with glucose and acatate. P. zopfii and P. wickerhamii are able to use urea, glycine, and glutamate as sources of nitrogen. P. spec. 263-2, on the other hand, cannot utilize these organic nitrogen compounds for growth.Four strains of Chlorella protothecoides are able to use glucose, fructose, galactose, and acetate as sources of carbon for growth in the dark. Three of them utilize also mannose, trehalose, and glutamate. Two strains can grow with glycerol, and one is able to use lactose. — Urea and glycine can serve as sources of nitrogen for the four strains of C. protothecoides. Glutamate supports growth of three strains, and one strain is able to use nicotinamide.     

Metabolism of Explosive Compounds by Sulfate-Reducing Bacteria

The metabolism of various explosive compounds—1,3,5-trinitrobenzene (TNB), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetraazocine (HMX)—by a sulfate-reducing bacterial consortium, Desulfovibrio spp., was studied. The results indicated that the Desulfovibrio spp. used all of the explosive compounds studied as their sole source of nitrogen for growth. The concentrations of TNB, RDX, and HMX in the culture media dropped to below the detection limit (<0.5 ppm) within 18 days of incubation. We also observed the production of ammonia from the nitro groups of the explosive compounds in the culture media. This ammonia served as a nitrogen source for the bacterial growth, and the concentration of ammonia later dropped to <0.5 mg/L. The sulfate-reducing bacteria may be useful in the anaerobic treatment of explosives-contaminated soil. Received: 23 January 1998 / Accepted: 5 March 1998     

SOME FACTORS IN THE COMPETITION OR ANTAGONISM AMONG BACTERIA, ALGAE, AND AQUATIC WEEDS

Field observations of changes in the populations of aquatic weeds and phytoplankton have confirmed that aquatic weeds have antagonistic activity toward phytoplankton. Nutritional studies in the laboratory indicate that cultures of the aquatic weeds, Myriophyllum sp., Ceratophyllum sp., and duckweed (Lemma minor L.); liquid cultures of barley (Hordeum vulgare L., Dickson variety); and cultures of the filamentous green algae, Cladophora sp. and Pithophora oedogonium (Mont.) Withrock, will remain relatively free of epiphytes or competing phytoplankton if the cultures are nitrogen-limited. Field observations of Cladophora sp. have confirmed that the growth of epiphytes on the Cladophora is related to conditions of surplus available nitrogen compounds. It is proposed that this antagonistic activity may be due to a “nitrogen sink” effect in which the aquatic weeds or filamentous green algae prevent the growth of contaminating algae by competition for the limited nitrogen compounds available. However, the presence of bacteria-sized organisms which have selective toxicity to certain algae indicates that perhaps multiple factors exist. Discussed are the ecological implications of associations of certain algae with bacteria that have selective toxicities for other species of algae under certain environmental conditions such as nitrogen-limited growth.     

Utilization of organic nitrogen compounds by Hydrogenomonas eutropha

The chemolithotroph, Hydrogenomonas eutropha, was tested for its ability to utilize a variety of single nitrogen sources during growth in an atmosphere of H₂? O₂? CO₂ The present data show that H. eutropha can utilize the nitrogen from many, but not all, amino acids, several sulfur-containing amino acids, glucosamine, and two aliphatic amides. The nitrogen concentration that supported maximum growth for NH₄Cl, L -glutamate, L -glutamine, urea, and glycine was in the 0.010–0.019M range. H. eutropha failed to remove the nitrogen from primary and secondary amines, eycloleucine, tert-DL -leucine, DL -p-fluorophenylalanine, DL -5-methyltryptophan, creatine, and creatine. This microorganism was able to partially degrade at least six substituted indoles and/or tryptophan catabolites and six substituted imidazoles and/or histidine catabolites. All of a series of 17 dipeptides were able to serve as a nitrogen source for growth in the absence of NH₄Cl. Extracts of H. eutropha were able to catalyze the hydrolysis of 16 α-dipeptides, 2 tripetides, a tetrapeptide, a polypeptide, a β-aspartyl peptide, 2 γ-glutamyl peptides, a N-acetyl amino acid, and 4 amino acid amides. These results emphasize the effectiveness of H. eutropha in utilizing a wide diversity of organic nitrogenous compounds containing amino and amide groups, heterocyclic rings, and peptide bonds.     

Molecular analysis of inorganic nitrogen assimilation in yeasts

Assimilation of nitrate and various other inorganic nitrogen compounds by different yeasts was investigated. Nitrate, nitrite, hydroxylamine, hydrazine, ammonium sulphate, urea and L-asparagine were tested as sole sources of nitrogen for the growth of Candida albicans, C. pelliculosa, Debaryomyces hansenii, Saccharomyces cerevisiae, C. tropicalis, and C. utilis. Ammonium sulphate and L-asparagine supported the growth of all the yeasts tested except D. hansenii while hydroxylamine and hydrazine failed to support the growth of any. Nitrate and nitrite were assimilated only by C. utilis. Nitrate utilization by C. utilis was also accompanied by the enzymatic activities of NAD(P)H: nitrate oxidoreductase (EC 1.6.6.2) and NAD(P)H: nitrite oxidoreductase (EC 1.6.6.4), but not reduced methyl viologen-or FAD-nitrate oxidoreductases (EC 1.7.99.4). It is demonstrated here that nitrate and nitrite reductase activities are responsible for the ability of C. utilis to assimilate primary nitrogen.     

Studies on Choanephoraceae. VIII. Interaction of carbon and nitrogen sources

Summary The effect of different carbon-nitrogen combinations on the growth and sporulation ofBlakeslea trispora, Choanephora cucurbitarum, Choanephora infundibulifera, Choanephora conjuncta, Choanephora heterospora andChoanephora circinans was studied. Both potassium nitrate and sodium nitrite were found to be useless for the present species, even when they were given in combination with different carbon compounds. In some of the cases only a little improvement in the growth was caused by combining poor carbon sources with good nitrogen sources.     

Regrowth dynamics of <Emphasis Type="Italic">Calamagrostis epigejos</Emphasis> after defoliation as affected by nitrogen availability

Young plants of a rhizomatous grass Calamagrostis epigejos (L.) Roth were grown from seed in nutrient solutions containing nitrogen in concentrations 0.1, 1.0, and 10 mM. After six weeks of cultivation the plants were defoliated and changes in growth parameters and in content of storage compounds were measured in the course of regrowth under highly reduced nitrogen availability. Plants grown at higher nitrogen supply before defoliation had higher amount of all types of nitrogen storage compounds (nitrates, free amino acids, soluble proteins), which was beneficial for their regrowth rate, in spite of lower content of storage saccharides. Amino acids and soluble proteins from roots and stubble bases were the most important sources of storage compounds for regrowth of the shoot. Faster growth of plants with higher N content was mediated by greater leaf area expansion and greater number of leaves. In plants with lower contents of N compounds number of green leaves decreased after defoliation significantly and senescing leaves presumably served as N source for other growing organs. Results suggest that internal N reserves can support regrowth of plants after defoliation even under fluctuating external N availability. Faster regrowth of C. epigejos with more reserves was mediated mainly by changes in plant morphogenesis.     

Response of walnut aphid populations to increasing foliar nitrogen content

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Spectrophometric analysis of volatile compounds in microorganisms

A simple modification of a spectrophometric method was proposed for the rapid detection of microorganisms based on their ability either to excrete or to absorb volatile compounds. The method provides the possibility of contactless control for bacterial growth at a concentration above 10⁷ cells/ml. In addition, the method allows discriminating mutants of the fungus Neurospora crassa defective in the nitrogen metabolism from the wild type strains. It is likely that nitrite reductase and nitrate reductase enzymes regulated by the nit-2 and nit-6 genes are involved in formation of the water soluble volatile compounds of this organism.