• Microbiology and Biotechnology Letters
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• v.47 no.1
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• pp.11-19
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• 2019

The properties of microalgae as bioresources for biodiesel production can be improved by adding nitrogen sources into the culture medium. Thus, Nannochloropsis oceanica CCAP 849/10 was cultured in f/2 media supplemented with five different forms of nitrogen at $0.88mmol-N\;l^{-1}$ each: ammonium bicarbonate ($NH_4HCO_3$), ammonium sulfate ($(NH_4)_2SO_4$), sodium nitrate ($NaNO_3$), ammonium nitrate ($NH_4NO_3$), and urea. The cell density, lipid content, and fatty acid profile of the microalga were determined after 15 days of cultivation. The growth of N. oceanica based on cell number was lowest in the medium with $NH_4NO_3$, and increased significantly in the medium with $NH_4HCO_3$. Cells treated with $(NH_4)_2SO_4$, and $NH_4NO_3$ produced the highest total lipid contents (i.e., 65% and 62% by dry weight, respectively). The fatty acid profiles of the microalga were significantly different in the various nitrogen sources. The major fatty acids detected in cultures supplemented with $NH_4HCO_3$, $(NH_4)_2SO_4$, $NH_4NO_3$, or urea were C14:0, C16:0, C16:1, C18:0, C18:1, C18:2, C20:5, and C22:6. However, the C16:1 content in the $NaNO_3$-supplemented culture was very low. This study highlights that the nitrogen source can strongly influence lipid production in N. oceanica and its fatty acid composition.

• Journal of Bio-Environment Control
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• v.21 no.3
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• pp.170-179
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• 2012

We examined pretreatment methods eliminating potassium and sodium efficiently for coir bag used in hydroponics by analyzing drainage coming from coir bags. In the first experiment we investigated for six coir bags with the high market shares. The three types of pretreatment were washing coir bags with only water for 7 days (W7S0), washing with water for 4 days and further with nutrient solution for 3 days (W4S3), and washing with only nutrient solution for 7 days (W0S7). In the second experiment we tested reproducibility of the experiment results for Bio Grow and coco Mix among six coir bags used in the first experiment to verify the results. As a result, the best pretreatments for the pH stabilization were W4S3 and W0S7. The EC value of the drainage was stabilized to less than 1.0 that is the same as EC of the supply solution on the fourth day in all treatments. The nutrients of the drainage in W7S0 was stabilized in 3~4 days but calcium and magnesium were depleted. We assessed that washing longer than 4 days was waste of water. The stabilization of coir bags in W0S7 was similar to it in W4S3, but washing with the nutrient solution for 7 days seemed to be uneconomical. The reproducibility experiment for two coir bags ensured the results in the first experiment. Therefore, the pretreatment method, which is the most simple to implement and economic, seems to wash with water for 3 days and then with the nutrient solution for 1 day before planting on coir bag.

• Journal of Korean Society of Forest Science
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• v.77 no.4
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• pp.361-370
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• 1988

This study was carried out for observation of growth, mycorrhizal formation and nutrient absorption of Pinus thunbergii seedlings treated with two soil mixtures and various nitrogen levels after inoculation with mycorrhizal fungus, Pisolithus tinctorius. 1. Seedlings grown on vermiculite applied with $50-150{\mu}g/ml$ nitrogen levels were well developed with pinnate type and cluster-like mycorrhizae. But seedlings on sandy loam had monopodial type in addition to the above-mentioned two types. 2. Optimum fertilization level for mycorrhizal formation is 50 or $150{\mu}g/ml$ N that showed best mycorrhizal formation of $86.4({\pm}3.14)%$ or $73.0({\pm}7.21)%$, respectively, but increased nitrogen levels decreased formation of mycorrhizal short roots. Seedlings applied with $450{\mu}g/ml$ nitrogen level decreased in net assimilation rate (NAR) and crop growth rate(CGR) during early growth of the seedlings, and they were increased since Aug, when nutrient application was stopped. 9. Inorganic nutrient absorption was increased more in seedlings grown on vermiculite and inoculated growth medium than those grown on sandy loam and noninoculated one, and it was gradually increased with increasing nitrogen increasing nitrogen level until $350{\mu}g/ml$. But $450{\mu}g/ml$ nitro gen level rather reduced absorption of nutrient.

• Journal of Bio-Environment Control
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• v.11 no.4
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• pp.168-174
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• 2002

A new circulating hydroponic system was invented for oriental melons grown in the greenhouse. For developing nutrient solution management techniques, we examined the changes of nutrient contents of circulating solution in three different types of new hydroponic systems. The yield and fruit quality of oriental melons in Hydroponics were better than those in soil culture. The substrate culture was appropriate fer hydroponics of oriental melons, and NFT was turned to be the opposite due to the physiological disorder during hot seasons. Yamazaki's melon solution with EC 2.0dS.m$^{[-10]}$ was the most appropriate for oriental melons. The new circulating hydroponic system seemed to be appropriate for oriental melons because of the stable EC, pH and the macro- and micro-element contents. NO$_3$-N, Ca and Mg contents in the circulating solution kept a good balance in all types of hydroponics. However, p content, compared to other types, decreased by the degree of 1 me.L$^{[-10]}$ in perlite medium. K content showed irregular status in perlite but showed the stable status in cocopeat. Generally, microelements, except Mo, showed stable absorption in the substrate culture. However, in NET, most of the elements showed irregular absorption except B and Mn. Microelement absorption, especially Cu, Zn and Mo, decreased during hot seasons.

• Korean Journal of Microbiology
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• v.39 no.3
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• pp.181-186
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• 2003

This study was performed to analyze quantitatively the number of living bacteria in forest soil samples collected from Mt. Keryong using improved direct viable count (DVC) and plate count (PC) methods. The number of living bacteria by DVC comprised 18～44% of the total direct count (TDC), whereas the number of living bacteria by PC was less than 1% of TDC. These results showed that viable but non-culturable (VBNC) bacteria existed in the soil with high percentages. Besides, DVC was proved to make it possible to make a quantitative detection of the VBNC bacteria. On the other hand, upon measuring the value from the conventional nutrient broth (NB) and $10^{-2}$ folded diluted nutrient broth (DNB), the values from the DNB showed 5 to 10 times higher than those from the conventional NB medium. These results indicate that oligotrophic bacterial groups, which could multiply in the low nutrient broth, abundantly exist in the soil ecosystem. It would also be possible to apply this kind of method to other substrate to make a quantitative detection of soil bacterial groups.

• Journal of Mushroom
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• v.20 no.2
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• pp.55-60
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• 2022

This study was conducted to establish an appropriate period of use of sawdust spawn at low temperatures and a nutrient supplement medium for cultivation of Lentinula edodes 'Hwadam'. Of the nutrient supplements, the total yield of rice bran (5%) + corn flour (5%) treatments were 673.3 g, which was higher than rice bran (551.6 g) and wheat bran (546.7 g) treatments, respectively. As shown by the growth of Lentinula edodes 'hwadam' during to the sawdust spawn storage period (at 4℃), the period of spawn running, browning, fruiting body formation, and development was 27 d, 81 d, 5 d, and 11-13 d, respectively, regardless of the length of the storage period at 4 ℃. After 3 months of storage of sawdust spawn, the number of fruiting bodies and yield decreased as the storage period increased. Therefore, the period of use of sawdust spawn (at 4 ℃) for the stable production of fruiting bodies of Lentinula edodes 'Hwadam' was a maximum of 3 months.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.4
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• pp.334-340
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• 1997

It was proven that rice straw can serve can serve as a good support medium for trickling filter with livestock wastewater treatment. The efficiency of removal of removal of environmentally undesirable components from the wastewater by the straw medium was no less inferior to other commonly used support materials. The treated straw was also proven to be a source of abundant plant nutrients. The growth of orchard grass was enhanced greatly by the application of large quantity of the support medium. A maximum yield of dry matter was obtained at the rate of 40 ton/ha. Inorganic NPK elements as background fertilizers were highly recommended for better development in an early stage of growth. The nutritional status of the soil was very much improved by the addition of the medium in terms of exchangeable cations(K, Ca, Mg and Na), available phosphate, and organic matter contents. Nutrient uptake by orchard grass such as N, P and cations was enhanced by rice straw medium treatment and that was proportional to the levels of treatment.

• Weed & Turfgrass Science
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• v.3 no.4
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• pp.336-341
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• 2014

Wetting agent is a substance that reduces the soil water repellency and causes a liquid to spread more easily into the soil. Wetting agents are well known as to improve irrigation efficiency. Phosphorus is one of the 17 essential nutrient elements and promote faster seed germination. The objective of this study was to evaluate wetting agent and P rates for fast germination and establishment of Kentucky bluegrass. Three levels of wetting agent which were 0.23, 0.46, and $0.92ml\;m^{-2}$ were applied and the P treatments were 5, 10, and $15g\;m^{-2}$. The medium and high rate of wetting agent at the high P rate had the greatest turfgrass coverage and took 28 days to reach 50% turfgrass coverage regardless of P application. Based on this study, wetting agent is effective for fast germination and establishment of Kentucky bluegrass if sufficient phosphorus is applied.

• Journal of Applied Biological Chemistry
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• v.44 no.4
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• pp.173-176
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• 2001

This report concerns the role of indole-3-acetic acid (IAA) in bacterial pustule disease of soybean. Pustule production in soybean leaves caused by Xanthomonas axonopodis pv. glycines was accompanied by a drastic increase in IAA content of host tissues. The phytopathogenic bacterium synthesized IAA in a tryptophan concentration-dependent manner when grown in a defined minimal medium. In complex media, however, the pathogen showed no response to tryptophan feeding, implying that the bacterial biosynthetic machinery of IAA is strictly regulated by nutrient availability of its growth environments. The results may suggest that IAA of bacterial origin and tryptophan of plant origin be involved in the process of pustule symptom development in soybean.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.331-337
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• 2000

When microorganism is injected into porous medium such as soils, biomass retained in the pore. Bacteria within these microcolonies produced large amounts of exopolysaccharides and formed a plugging biofilm. Soil pore size and shape are varied from the initial condition as a result of biofilm formation, which make hydraulic conductivity reduced and friction rate between soil aggregates increased. In this research, hydraulic conductivity reduction was measured after microorganism are inoculated and cultured with synthetic substrate and nutrient. Also, pore sand of before and after biofilm formation compared with scanning electron microscopy. Hydraulic conductivity of Sand and Poorly Graded Sand was decreased approximately 1/10∼1/100 after biomass inoculation and cultivation. Biofilm attached on soil aggregates is resistant to acidic or basic condition.