• Korean Journal of Soil Science and Fertilizer
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• v.47 no.2
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• pp.107-112
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• 2014

Glomalin has been suggested as an enhancer for soil stability by promoting the aggregation. In this study, we examined the concentrations of glomalin and microbial characteristics in 25 controlled horticultural soils sampled from Gyeongnam Province. Total glomalin had a significant positive correlation with soil organic matter (p < 0.01), soil microbial biomass carbon (p < 0.05), and dehydrogenase activity (p < 0.05) in controlled horticultural soils. In addition, the total glomalin had a significant positive correlation with concentrations of total fatty acid methyl esters, Gram-negative and Gram-positive bacteria, fungi, and arbuscular mycorrhizal fungi in controlled horticultural soils (p < 0.001). In conclusion, the concentration of total glomalin could be an indicator of microbial biomass richness for sustainable agriculture in controlled horticultural soils.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.6
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• pp.487-493
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• 2013

The effects of long-term fertilization on soil biological properties and microbial community structure in the plough layer in a rice paddy soil in southern Korea were investigated in relation to the continuous application of chemical fertilizers (NPK), straw based compost (Compost), combination these two (NPK + Compost) for last 40 years. No fertilization plot (Control) was installed for comparison. Though fertilization significantly improved rice productivity over control, the long-term fertilization of NPK and compost combination was more effective on increasing rice productivity and soil nutrient status than single application of compost or chemical fertilizer. All fertilization treatments had shown significant improvement in soil microbial properties, however, continuous compost fertilization markedly increased soil enzyme and microbial activities as compared to sole chemical fertilization. Results of microbial community structure, evaluated by EL-FAME (ester-linked fatty acid methyl esters) method, revealed big difference among Control, NPK, and Compost. However, both Compost and Compost+NPK treatments belonged to the same cluster after statistical analysis. The combined application of chemical fertilizer and organic amendments could be more rational strategy to improve soil nutrient status and promote soil microbial communities than the single chemical fertilizer or compost application.

• Korean Journal of Food Science and Technology
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• v.25 no.3
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• pp.288-294
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• 1993

Solubilities of urea-crystallized tuna oil methyl esters in supercritical carbon dioxide were determined by a flow through extraction reactor. Experimental results obtained under a quasi-equlibrium condition showed that at 150 bar, solubilities of the esters in supercritical $CO_2$ were 0.075, 0.028 and 0.006(w/w) at $40^{\circ}C,\;60^{\circ}C\;and\;80^{\circ}C$, respectively. In the pressure and temperature ranges $(100{\sim}200bar\;and\;40{\sim}80^{\circ}C)$, the solubility increased with the density of $CO_2$. However, selectivity of supercritical carbon dioxide on the extracted compounds was much better at low density than at high density. Supercritical fractionation with a temperature gradient $(50{\sim}75^{\circ}C)$ resulted in concentrates of EPA and DHA in purities of 12% and 85%, respectively.

• ALGAE
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• v.31 no.3
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• pp.267-276
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• 2016

Microalgae are currently a very promising source of biomass and triacylglycerol (TAG) for biofuels. In a previous study, we identified Chlorella saccharophila as a suitable source of oil for biodiesel production because it showed high biomass and lipid content with an appropriate fatty acid methyl esters profile. To improve the TAG accumulation in C. saccharophila, in this study we evaluated the effect of abscisic acid (ABA) addition on cell concentration, lipid content and TAG production in this microalga. First, we evaluated the effects of four ABA concentrations (1, 4, 10, and 20 μM) added at the beginning of a single-stage cultivation strategy, and found that all concentrations tested significantly increased cell concentration and TAG content in C. saccharophila. We then evaluated the addition of 1 μM ABA during the second stage of a two-stage cultivation strategy and compared it with a nitrogen deficiency treatment (ND) and a combination of ND and ABA (ND + ABA). Although ABA alone significantly increased lipid and TAG contents compared with the control, ND showed significantly higher TAG content, and ND + ABA showed the highest TAG content. When comparing the results of both strategies, we found a superior response in terms of TAG accumulation with the addition of 1 μM ABA at the beginning of a single-stage cultivation system. This strategy is a simple and effective way to improve the TAG content in C. saccharophila and probably other microalgae as a feedstock for biodiesel production.

• Applied Chemistry for Engineering
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• v.25 no.6
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• pp.553-558
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• 2014

Microalgae are a promising alternative feedstock for biodiesel production because their growth rates and oil contents are higher than those of conventional energy crops. Microalgal lipid is mainly triacylglyceride that can be converted to biodiesel as fatty acid methyl esters through trans-esterification. In this paper, the influence of several important lipid inducing factors such as nutrient limitation and changes in salinity and metallic components in microalgae and their potential strategies to be used for biodiesel production are reviewed. Depending upon strains/species that we use, microalgae react to stresses by producing different amount of triacylglyceride and/or by altering their fatty acids composition. Although the most widely applied method is the nitrogen starvation, other potential factors, including nutrient surplus conditions and changes in salinity, pH, temperature and metal concentrations, should be considered to increase biodiesel productivity.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.6
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• pp.933-940
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• 2013

In this study, methyl esters with different saturated fatty acids (SFA) were prepared by urea fractionation to make an oil-in-water emulsion. Emulsion characteristics (emulsion stability and oxidative stability) of the methyl ester emulsion were then studied at different percentages of methyl ester saturation (5, 28, 39, 50, and 72%, termed ${\Sigma}$SFA5, ${\Sigma}$SFA28, ${\Sigma}$SFA39, ${\Sigma}$SFA50, and ${\Sigma}$SFA72, respectively). The stability of emulsions (ES) with different SFA content was 46.0 (${\Sigma}$SFA5), 39.5 (${\Sigma}$SFA28), 32.7 (${\Sigma}$SFA39), 32.6 (${\Sigma}$SFA50), and 27.3 (${\Sigma}$SFA72). Results from Turbiscan showed that creaming or clarification, based on the backscattering intensity, was more pronounced with increases in the saturation degree of the emulsion. These results implied that the emulsions with lower saturation were more stable. During 30 days of storage, the lipid peroxide value increased for all emulsions, with the increase less pronounced with the increasing saturation of the emulsion; 1.880 (${\Sigma}$ SFA5), 1.267 (${\Sigma}$SFA28), 1.062 (${\Sigma}$SFA39), 0.342 (${\Sigma}$SFA50) and 0.153 (${\Sigma}$SFA72) mg $H_2O_2/mL$ emulsion. In addition, thiobarbituric acid reactive substances (TBARS) values were significantly lower in emulsions with high saturation (4.419 mg for ${\Sigma}$SFA50 and 4.226 mg for ${\Sigma}$SFA72) than emulsions with low saturation (6.229 mg for ${\Sigma}$SFA5, 6.801 mg for ${\Sigma}$SFA28 and 6.246 mg for ${\Sigma}$SFA39). In conclusion, the emulsions with a higher saturation degree of methyl esters showed lower emulsion stability but better oxidation stability.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.251.1-251.1
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• 2010

바이오디젤은 동식물성 기름과 메탄올의 트랜스에스테르화 반응에 의해 생산되는 지방산메틸에스테르(FAME, fatty acid methyl esters)로서, 트랜스에스테르화 공정에는 KOH, NaOH, $NaOCH_3$등의 균질계 화학촉매를 이용한 방법, 무촉매 공정인 초임계 메탄올 이용 방법, 그리고 효소촉매를 이용한 방법이 있다. 초임계 공정은 에너지 소비와 장치비가 커서 경제성이 떨어지는 것으로 보고되며 화학촉매 공정은 반응 효율이 높다는 장점을 가지고 있지만, 반응 및 정제단계가 복잡하고 정제과정에 폐수를 발생시키는 문제점을 가지고 있다. 고정화 효소를 사용하는 효소 공정은 에너지 비용의 절감, 후 처리 공정의 단순화, 고 순도의 글리세롤을 얻을 수 있는 장점이 있지만, 반응 속도가 느리고 효소 가격이 비싸다는 단점이 있어 현재까지 상업화되지 못하고 있다. 반응속도가 높고 재사용이 가능한 효소 촉매 공정 개발을 위해 본 연구에서는 Candida rugosa, Rizhopus oryzae 2종을 실리카에 동시 고정화하였다. 고정화 Lipase의 제조는 실리카겔을 과산화수소를 이용하여 전처리를 하고 Acetone과 3-APTES의 혼합용액을 첨가한 후 실리카겔과 (silanization)을 진행 하였다. 그리고 glutaraldehyde를 첨가 하여 공유 결합을 형성 한 후에 증류수를 사용하여 실리카겔을 회수하여 lipase(Rizhopus oryzae, Candida rugosa 10% 용액)를 고정화 하였다. 고정화 효소의 효소 활성을 측정한 결과 3000-3500 Unit(${\mu}mol/g{\cdot}min$)으로 측정되었다. 제조된 고정화 효소를 이용하여 Canola Oil을 바이오디젤로 전환하는 실험을 진행하였으며 생성물로부터 고정화 효소를 분리한 후에 상층의 에스테르층을 취하여 수세한 뒤 원심분리하여 FAME 함량을 측정한 결과 83%의 바이오디젤을 얻을 수 있었다. 그리고 효소 촉매 트랜스에스테르화 반응의 Enzyme, Water, Methanol 투입량의 반응 변수들에 대하여 반응표면분석법(Response Surface Methodology)을 적용하여 최적 반응조건을 도출하는 연구를 수행하였다.

• Advances in environmental research
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• v.2 no.1
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• pp.19-33
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• 2013

Microalgae are receiving an increasing attention because of their potential use as $CO_2$ capture method and/or as feedstock for biofuels production. On the other hand the current microalgae-based technology is still not widespread since it is characterized by technical and economic constraints that hinder its full scale-up. In such contest the growth kinetics of Nannochloris eucaryotum (a relatively unknown marine strain) in batch and semi-batch photobioreactors is quantitatively investigated with the aim of obtaining the corresponding kinetic parameters suitable for process engineering and its optimization. In particular the maximum growth rate was evaluated to be 1.99 $10^{-3}\;h^{-1}$. Half saturation concentrations for nitrates ($K_N$) and phosphates uptake ($K_P$) were evaluated as 5.4 $10^{-4}\;g_N\;L^{-1}$ and 2.5 $10^{-5}\;g_P\;L^{-1}$, respectively. Yield factors for nitrogen ($Y_N$) and phosphorus ($Y_P$) resulted to be 5.9 $10^{-2}\;g_N\;g^{-1}$ biomass and 6.0 $10^{-3}\;g_P\;g^{-1}{_{biomass}}$, respectively. The possibility of using 100% (v/v) $CO_2$ gas as carbon source is also evaluated for the first time in the literature as far as N. eucaryotum is concerned. The strain showed a good adaptability to high concentrations of dissolved $CO_2$ as well as to low pH. The lipid content under 100% $CO_2$ is about 16.16 %wt $wt^{-1}$ and the fatty acid methyl esters composition of the extracted oil is in compliance with the European regulation for quality biodiesel.

• Journal of Ginseng Research
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• v.40 no.4
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• pp.453-461
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• 2016

Background: This study aims to describe the characterization of Paenibacillus polymyxa GBR-1 (GBR-1) with respect to its positive and negative effects on plants. Methods: The morphological characteristics of GBR-1 were identified with microscopy, and subjected to Biolog analysis for identification. Bacterial population and media optimization were determined by a growth curve. The potential for GBR-1 as a growth promoting agent, to have antagonistic activity, and to have hydrolytic activity at different temperatures was assessed. The coinoculation of GBR-1 with other microorganisms and its pathogenicity on various stored plants, including ginseng, were assessed. Results: Colony morphology, endospore-bearing cells, and cell division of GBR-1 were identified by microscopy; identification was performed by utilizing the Biolog system, gas chromatography of fatty acid methyl esters (GC-FAME). GBR-1 showed the strongest antagonistic activity against fungal and bacterial pathogens. GBR-1 cell numbers were relatively higher when the cells were cultured in brain heart infusion (BHI) medium when compared with other media. Furthermore, the starch-hydrolytic activity was influenced by GBR-1 at higher temperature compared to low temperatures. GBR-1 was pathogenic to some of the storage plants. Coinoculation of GBR-1 with other pathogens causes differences in rotting on ginseng roots. A significant growth promotion was observed in tobacco seedlings treated with GBR-1 suspensions under in vitro conditions, suggesting that its volatile organic compounds (VOCs) might play a role in growth promotion. Conclusion: The results of this study indicate that GBR-1 has both positive and negative effects on ginseng root and other stored plants as a potential biocontrol agent and eliciting in vitro growth promotion.

• Journal of Environmental Health Sciences
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• v.23 no.4
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• pp.115-120
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• 1997

The purpose of thesis was to investigate the removal efficiency of surfactants and commercial detergents by Oenanthe javanica that is one of aquatic plants in Korea. The experiment is concerned with measuring the concentrations of surfactants and commercial detergents in different media: 1) in pure water, 2) in water containing Oenanthe javanica, 3) in water containing Oenanthe javanica and commercial nutrients. The surfactants used in this research include linear alkylbenzene sulfonates (LAS), $\alpha$-sulfo fatty acid methyl esters(MES), and alkylbenzene sulfonates(ABS). Two commercial detergents designated as A and B were in the forms of power and liquid. The results showed that LAS and MES were more effectively removed by Oenanthe javanica probably because these have a chain of linear carbon than on ABS with a branched carbon structure. In the case of commercial detergents, when the except was performed on the basis of surfactants proportion, the removal trends were similar to LAS and MES. The 5-day cultivating test with initial concentration of 0.5-1.0 ppm surfactants showed that less than 10% was removed if no nutrients an Oenanthe javanica were added. When Oenanthe javanica was added into the sample solution containing surfactants, the removal efficiency was increased 100% for the solution containing 0.5-1.0 ppm 60-70% for 5-10 ppm. In addition, chlorisis on Oenanthe javanica was observed due to surfactants and commercial detergents for all three cases. To test the dependence of population density on nutrients, the initial population density was made 300 g/0.4 m$^2$. Throughout the 5-day experiment, the on Oenanthe javanica grew 20-25% with 0.5-1.0 ppm without the synthetic nutrients but by 5% with a high concentrations of 5-10 ppm. The population density was appeared to be independent of synthetic nutrients. The leaves were to be grown with synthetic nutrients, while roots were grown without synthetic nutrients. Based on this research, the fundamental data concerning cultivation and an adequate adjustment of the water condition can provide for the utilization of Oenanthe javanica in real water treatment system.