• Journal of Applied Biological Chemistry
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• v.49 no.1
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• pp.28-32
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• 2006

Effect of organic-C on immobilization and nitrification patterns in acidic soil was examined during 20 weeks incubation period to verify if organic amendments such as composted material can increase soil retention of N by stimulating microbial immobilization of $NH_4^+$. Four treatments were laid out: control without fertilizer N and glucose (treatment code: S), ammonium sulfate (SN), ammonium sulfate with single glucose at the commencement (0 week) of incubation (SNG), and ammonium sulfate with double glucose at 0 and 4 weeks of incubation (SNGG). Glucose application (SNG) significantly increased microbial immobilization of $NH_4^+$ within 1 week of incubation over SN. Immobilization was followed by remineralization thereafter; however, second-application of glucose (SNGG) restored $NH_4^+$ immobilization. At the same time, nitrification was significantly inhibited by glucose application as indicated by consistently low $NO_3^-$ concentration in SNG and SNGG soils, suggesting that microbial assimilation of $NH_4^+$ is predominant compared to nitrification when available C-source is abundant. These results suggest application of chemical fertilizer-N with organic amendment would have beneficial effect on soil-N retention and environmental conservation by reducing production of $NO_3^-$ which is likely to be lost through leaching or denitrification.

• Journal of Bio-Environment Control
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• v.5 no.2
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• pp.120-130
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• 1996

Crisphead lettuce(Lactuca sativa L.) was grown in NFT to investigate the effects of NO$_3$-N and NH$_4$-N ratio in nutrient solution and elevated $CO_2$ treatment in the crisphead lettuce growth. This experiment has been conducted under three different ratios of NO$_3$-N:NH$_4$-N(100:0, 75:25, 50:50) with two $CO_2$ concentration (control, 1500ppm ). The results are as follows; 1. In the case of not controlling pH and EC in nutrient solution, pH was gradually increased in NO$_3$-N:NH$_4$-N=100:0 treatment but rapidly decreased in the nutrient solution 2. Daily changes of NO$_3$-N and NH$_4$-N were observed without controlling the nutrient solution. In the treatments of NO$_3$-N:NH$_4$-N ratios were 75:25 and 50:50, NO$_3$-N absorption rates were 27.7% and 26.1%, while NH$_4$-N absorption rates were 87.9% and 71.2%, respectively. 3. There was little differences in total nitrogen of leaves. However phosphorus, potassium, calcium and magnesium contents were highly shown in the treatment of $CO_2$ 1500ppm and 100:0 ratio of NO$_3$-N:NH$_4$-N. 4. Higher $CO_2$ assimilation rate was shown in plants grown under $CO_2$ 1500ppm and 100:0 ratio of NO$_3$-N:NH$_4$-N. It dropped significantly with the increase of NH$_4$- N rates in nutrient solution. 5. Fresh weight, leaf number, root length and root weight of crisphead lettuce were far better in the treatment of $CO_2$ 1500ppm and 100:0 ratio of NO$_3$-N:NH$_4$-N. Growth differences by $CO_2$ elevation were not shown in other NO$_3$-N:NH$_4$-N treatments. 6. The highest nitrate contents of leaves were shown in NO$_3$-N single treatment but shown the lowest vitamin C contents. Nitrate contents of leaves were decreased by $CO_2$ but the effect was slight treatment.

• The Korean Journal of Mycology
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• v.27 no.6 s.93
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• pp.386-393
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• 1999

Ethanol is considered as one of the most suitable substitutes for the petroleum, since it offers attractive functional features at an economical cost. Glucoamylase producing yeasts were isolated and characterized. Based on the morphological character, carbon fermentations, assimilation of carbon and nitrate, growth on vitamine-free medicine, and urease activity, five isolates of Saccharomyces diastaticus, two isolates of Saccharomycopsis fibuligera, and two of Schwanniomyces occidentalis, and each isolate of Ambrosiozyma monospora and Lipomyces kononenkoae were identified. Among 12 isolates, one of the S. diastaticus, E3 showed the highest activity of glucoamylase and identified as Saccharomyces diastaticus. The hydrolysis of starch by the E3 strain showed the release of considerable amount of reducing sugar, along with the reduction in iodine staining capacity. The product of action of glucoamylase, glucose was determined by thin-layer chromatography. The enzyme activity was found to be stable in broad pH range of $5.0{\sim}7.0$ with optimal activity at pH $5.0{\sim}6.0$. The enzyme showed optimal antivity at $50^{\circ}C{\sim}60^{\circ}C$. Soluble starch and glucose were better carbon sources for the enzyme production than xylose and glycerol. $Na^+\;and\;Mg^{2+}$ increased the glucoamylase activity, however $Hg^{2+}\;and\;Ag^{2+}$ inhibited the activity. Soluble starch was the best substrate for the enzyme activity.

• Korean Journal of Soil Science and Fertilizer
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• v.35 no.5
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• pp.314-325
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• 2002

The effects of arbuscular mycorrhizal (AM) fungus (Glomus intraradices) on plant growth and N metabolic responses were examined in perennial ryegrass plants exposed to drought-stressed or well-watered condition. Mycorrhizal inoculation improved significantly leaf water potential, dry mass and P content. Drought stress increased significantly nitrate concentration in roots where the increase was much less in AM than non-AM. Drought stress decreased the concentration of soluble proteins in non-AM shoots, whereas non-significant decline occurred in AM shoots even under drought condition. The concentrations of ammonia and proline in drought stressed non-AM plants significantly increased, while mycorrhizal inoculation lowered significantly ammonia and proline accumulation. The decrease in leaf dry weight in drought stressed-plants was significantly correlated to the increase in ammonia (p<0.01) and proline concentration (p<0.01). These results suggested that the increased P content and N assimilation by mycorrhizal inoculation may be associated with drought stress tolerance, showing the moderating effects on shoot growth inhibition and ammonia accumulation in drought stressed-plants.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.5
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• pp.779-786
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• 2012

Many farmers have been seeking alternatives to chemical fertilizer for successful organic fruit production. This experiment was carried out to investigate the replaceability of chemical fertilizer by cover crop and slurry composting biofiltration (SCB) liquid manure (LM) application in pear orchard. Three treatments were contained in this experiment; cover crop only and cover crop + LM treatment, and control (chemical fertilizer application). Dry weight and mineral contents of gramineous cover crops were significantly increased in LM-combined treatments than that of leguminous species. Bulk density of soil was decreased in rye + LM and hairy vetch + LM treatments, compared with each cover crop treatment. Soil pH was lowest in fertilizer treatment and soil nitrate content became similar between treatments after rainy season. Available soil phosphate was lower in cover crop and cover crop + LM treatmemts than control, but exchangeable Mg was higher. The mineral content and net assimilation rate of leaves showed no difference between the treatments. As a result, it is suggested that the application of SCB liquid manure in pear orchard managed by cover crops is desirable to maintain the productivity by improving soil physical properties and potential nutrient recovery.

• Asian Journal of Turfgrass Science
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• v.25 no.2
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• pp.171-176
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• 2011

Sclerotinia homoeocarpa, the causal agent of dollar spot, is one of the most common pathogens of cool season turfgrasses in South Korea. The vegetative compatibility group (VCG) assay was carried out using nitrate-nonutilizing (nit) mutants recovered from 13 South Korean isolates with various geographical origins. The mutants were divided into four phenotypic classes based on mutation loci associated with nitrogen assimilation: nit1, nit2, nit3, and NitM. The recovered number of nit mutants greatly varied among the isolates, ranging from 0 to 15 mutants. Of the mutants isolated, nit1 and nit2 mutants were most common (80%) while NitM and nit3 were relatively rare. One dominant and four minor VCGs were determined from 18 mutant isolates tested. To study population structures of Korean S. homoeocarpa isolates and increase our understanding of its ecological and epidemiological aspects for dollar spot management on turfgrass, more generated mutants should be tested with more diverse isolate collections.

• 한국해양학회지
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• v.23 no.4
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• pp.194-206
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• 1989

Seasonal variations of nutrients (ammonium, nitrite, nitrate, phosphate and silicate), primary productivity and ammonium regeneration rate of macrozooplankton were investigate to understand the relationship between nitrogen recycling and nitrogen requirement by phytoplankton from Feburuary 1986 to November 1987 in the Kyunggi Bay, shallow estuarine water of Yellow Sea. In general, nutrients increased during the winter and depleted during the spring and the early summer except temporally sharp increase after flood in September. Ammonium was prevalently generally found in high concentration throughout the study area and it occasionally raised N/P ratio in the range of 30 to 70 as in the freshwater environment. Daily net primary productivity ranged from 30.3 to 3580.0 mgC/$m^2$/d with an average of 883.9 mgC/$m^2$/d. Annual primary productivity was determined to be 320.0 gC/$m^2$/yr. Carbon assimilation number ranged from 2.9 to 19.4 mgC/mg chl-a/h which increased in the summer and decreased in the winter. Nitrogen requirement by phytoplankton ranged from 0.4 to 45.0 mg at-N/$m^2$/d and turnover time of inorganic nitrogen ranged from 2.4 in the late summer to 122.7 days in the winter. Nitrogen regeneration rate of mixed macrozooplankton determined by bottle incubation method ranged from 0.02 to 1.34 mg at-N $m^2$/d and it could contribute from 2.8 to 38.7% with an annual average of 14.9% of total nitrogen requirement by phytoplankton in this shallow estuarine environment.

• Journal of The Korean Society of Grassland and Forage Science
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• v.22 no.3
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• pp.153-160
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• 2002

To investigate the effects of the exogenous N $O_3$$^{[-10]}$ supply level on the nitrate assimilation and growth during the vegetative growth stage, and on the accumulation of organic reserves during the successive regrowth period, dry matter (DM), the amount of nitrogenous compounds, total N and starch in alfalfa plants grown hydroponically with 0.2, 1.0 and 3.0 mM KN $O_3$ was estimated, respectively, during vegetative growth period and two cycle of regrowth. When compared with DMs and N contents in various N compounds in the organs grown with 1.0 mM N $O_3$$^{[-10]}$ , N starvation symptoms were found in 0.2 mM and a depressive effect was observed in 3.0 mM after 10 weeks of vegetative growth. Total starch content in root system gown with 0.2, 1.0 and 3.0 mM N $O_3$$^{[-10]}$ during the first regrowth was 50.96, 15.47 and 6.37 mg plant$^{-1}$, respectively. Starch was contained mainly in taproots. The starch content was not significantly changed by 24 days of the second regrowth with 1.0 mM N $H_4$N0$_3$. Total nitrogen content in root system grown with 0.2, 1.0 and 3.0 mM N $O_3$$^{[-10]}$ during the first regrowth was 6.66, 8.43 and 11.09 mg plant$^{-1}$ , respectively. Nitrogen was contained mainly in lateral roots; 80% (in 0.2 mM), 74% (1.0 mM) and 76% (3.0 mM) of total nitrogen in root system. Total N content in root system at the end of the second regrowth also closely affected by the N $O_3$$^{[-10]}$ supply level during the first regrowth. These results suggest that the level of N $O_3$$^{[-10]}$ may strongly influence the accumulation of organic reserves in root system, and that the initial level of organic reserves for the successive regrowth was one of the determinants for shoot regrowth.

• Microbiology and Biotechnology Letters
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• v.41 no.1
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• pp.17-25
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• 2013

The thermotolerant methylotrophic yeast Hansenula polymorpha is an attractive model organism for various fundamental studies, such as the genetic control of enzymes involved in methanol metabolism, peroxisome biogenesis, nitrate assimilation, and resistance to heavy metals and oxidative stresses. In addition, H. polymorpha has been highlighted as a promising recombinant protein expression host, especially due to the availability of strong and tightly regulatable promoters. In this study, we investigated the possibility of employing human serum albumin (HSA) as the fusion tag for the secretory expression of heterologous proteins in H. polymorpha. A set of four expression cassettes, which contained the methanol oxidase (MOX) promoter, translational HSA fusion tag, and the terminator of MOX, were constructed. The expression cassettes were also designed to contain sequences for accessory elements including His8-tag, $2{\times}(Gly_4Ser_1)$ linkers, tobacco etch virus protease recognition sites (Tev), multi-cloning sites, and strep-tags. To determine the effects of the size of the HSA fusion tag on the secretory expression of the target protein, each cassette contained the HSA gene fragment truncated at a specific position based on its domain structure. By using the Green fluorescence protein gene as the reporter, the properties of each expression cassette were compared in various conditions. Our results suggest that the translational HSA fusion tag is an efficient tool for the secretory expression of recombinant proteins in H. polymorpha.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.1
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• pp.83-89
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• 2010

We investigated the growth of cucumber plants, the uptake and use of mineral nutrients, such as $NO_3$-N, $NH_4$-N, $K^+$, $Ca^{+}^{+}$, $Mg^{+}^{+}$ and $Na^+$, absorbed from media solution, and the synthesis and distribution of soluble sugars under nutrient-deficient condition. Difference in plant growth revealed after 20 days of treatment. Nitrate uptake in nutrient-deficient condition was significantly reduced compared with nutrient-normal treatment, and its distribution was primarily in petioles, stem, roots and less in leaves. In contrast, ammonium content was markedly predominated in fast growing organs, and it was significantly different in growing leaves, expanded leaves, and roots under similar growth conditions. $K^+$, lack by deficient nutrient condition, was found in growing leaves. The $Ca^{+}^{+}$ content did not show significant difference between treatments and a substantial portion of $Ca^{+}^{+}$ remained in petioles. The $Mg^{+}^{+}$ content was significantly higher in the leaves of nutrient-normal condition compared with nutrient-deficient condition while significantly lower in stem and roots. The behavior of $Na^+$ in plant was similar to $K^+$ although its content was relatively little. The highest $CO_2$ assimilation was observed in fully expanded leaves of nutrient-normal condition, which was 1.7 times higher compared with nutrient-deficient condition. The instantaneous water use efficiency (A/E) and the A/gsratio, which is an index of leaf intrinsic water use efficiency for individual leaves, was 1.2 and 1.1 times higher, respectively. The total soluble sugar (TSS) contents were highest in leaves followed by petioles, stems and roots, and in younger leaves. The growing leaves contained about 7,200 mg $kg^{-1}$ of TSS in nutrient-normal condition whereas the TSS contents in nutrient-deficient condition were not significantly different between leaves. The $Mg^{+}^{+}$ and $NH_4$- N were positively correlated with the TSS whereas $NO_3$ - N was negatively correlated.