• Environmental Engineering Research
• /
• v.23 no.2
• /
• pp.205-209
• /
• 2018

The spectral composition of light can affect the growth and biochemical composition of photosynthetic microalgae. This study examined the use of light filtering through a solution of soluble colored additives, a cost-effective method to alter the light spectrum, on the growth and lipid production of an oleaginous microalga, Nannochloropsis gaditana (N. gaditana). Cells were photoautotrophically cultivated under a white light emitting diode (LED) alone (control) or under a white LED that passed through a solution of red and yellow color additive (4:1 ratio) that blocked light below 600 nm. The specific growth rate was significantly greater under filtered light than white light ($0.2672d^{-1}$ vs. $0.1930d^{-1}$). Growth under filtered light also increased the fatty acid methyl ester (FAME) yield by 22.4% and FAME productivity by 80.0%, relative to the white light control. In addition, the content of saturated fatty acids was greater under filtered light, so the biodiesel products had better stability. These results show that passing white light through an inexpensive color filter can simultaneously enhance cellular growth and lipid productivity of N. gaditana. This approach of optimizing the light spectrum may be applicable to other species of microalgae.

• Korean Journal of Soil Science and Fertilizer
• /
• v.44 no.6
• /
• pp.1158-1163
• /
• 2011

The present study was aimed to evaluate the soil microbial communities by fatty acid methyl ester (FAME) method in paddy soils at 20 sites in Gyeongnam Province. The soil microbial biomass carbon content of fan and valley $1,266mg\;kg^{-1}$ was higher than alluvial plain $578mg\;kg^{-1}$ (p<0.05). In addition, The dehydrogenase activity of fan and valley $204{\mu}g\;TPF\;g^{-1}\;24h^{-1}$ was higher than alluvial plain $93{\mu}g\;TPF\;g^{-1}\;24h^{-1}$ (p<0.05). The communities of total bacteria and Gram-negative bacteria in the fan and valley paddy soils were significantly higher than those in the alluvial plain paddy soils (p<0.05). Total bacteria communities should be considered as a potential responsible factor for the obvious microbial community differentiation that was observed between the fan and valley and alluvial plain in paddy soils.

• Korean Journal of Soil Science and Fertilizer
• /
• v.44 no.1
• /
• pp.118-126
• /
• 2011

Ester-linked fatty acid methyl ester (EL-FAME) profiles were used to describe differences in soil microbial communities influenced by conventional farming system (CFS), and organic farming system (OFS) in controlled horticultural land. Soil physicochemical properties and soil microbial communities were determined in the experimental fields. Higher organic matter content in OFS reduced soil bulk density which in turn increased the soil porosity. Generally, soil chemical properties in OFS were higher than those of CFS, but EC value in OFS was significantly lower than that of CFS. With the exception of Fe content, other macronutrient contents and pH in both farming system decreased with the soil depth. Soil microbial biomass of OFS was approximately 1.3 times in topsoil and 1.8 times in subsoil higher than those of CFS. Lower ratios of cy17:0 to $16:1{\omega}7c$ and cy19:0 to $18:1{\omega}7c$ were found in the CFS soils than the OFS soils, indicating that microbial stress decreased. The ratio of MUFA to SFA was higher in OFS due to organic input to the soil. In principal components analysis (PCA), the first variable accounted for 54.3%, while the second for 27.3%, respectively. The PC1 of the PCA separated the samples from CFS and OFS, while the PC2 of the PCA separated the samples from topsoil and subsoil. EL-FAMEs with the positive eigenvector coefficients for PC1 were cy17: 0 to $16:1{\omega}7c$ ratio, cy19:0 to $18:1{\omega}7c$ ratio, soil pH, soil organic matter, and soil $NO_3$-N content. Our findings suggest that the shifting cy19:0 to $18:1{\omega}7c$ ratio should be considered as potential factors responsible for the clear microbial community differentiation observed between different cultivation systems and soil depth in controlled horticultural land.

• Polymer(Korea)
• /
• v.25 no.3
• /
• pp.391-398
• /
• 2001

Two-component polyurethane (PU) flame-retardant coatings were prepared by blending tribromo modified polyesters ($TBAO_s$) and isocyanate.$TBAO_s$ were synthesized by condensation polymerization of tribromoacetic acid, a flame-retardant component, with 1,4-butanediol, adipic acid, and trimethylolpropane. The content of tribromoacetic acid was varied by 10, 20, and 30 wt% for the reaction. Various physical properties of these new flame-retardant coatings were comparable to nonflame-retardant coatings. Coatings with 20 wt% tribromoacetic acid did not burn during the vertical burning test.

• ALGAE
• /
• v.35 no.3
• /
• pp.277-292
• /
• 2020

Omega-3 fatty acids, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are polyunsaturated fatty acids beneficial to human health. A limited number of microalgae have been used for commercial omega-3 production, which necessitates the identification of new microalgae with high omega-3 contents. We explored the fatty acid composition and EPA and DHA contents of the mixotrophic dinoflagellate Gymnodinium smaydae fed with the optimal algal prey species Heterocapsa rotundata. Cells of G. smaydae were found to be rich in omega-3 fatty acids. In particular, the DHA content of G. smaydae was 21 mg g^-1 dry weight, accounting for 43% of the total fatty acid content. The percentage of DHA in the total fatty acid content of G. smaydae was the highest among the reported microalgae except for Crypthecodinium cohnii. Moreover, to determine if the prey supply interval affected the growth rate of G. smaydae and its fatty acid content, three different prey supply intervals (daily, once every 2 d, and once for 4 d) were tested. Daily prey supply yielded the highest total fatty acid and DHA contents in G. smaydae. Furthermore, we successfully produced high-density G. smaydae cultures semi-continuously for 43 d with daily prey supply. During the semi-continuous cultivation period, the highest density of G. smaydae was 57,000 cells mL^-1, with an average growth rate of 0.7 d^-1. Taken together, the percentage of EPA and DHA in the total fatty acid content was maintained in the range of 54.2-56.9%. The results of this study support G. smaydae as a promising microalgal candidate for commercial DHA production and demonstrate that daily supply of prey can efficiently produce high-density G. smaydae cultures for more than a month.

• Korean Journal of Environmental Agriculture
• /
• v.27 no.2
• /
• pp.133-138
• /
• 2008

Fire can affect microbial community structure of soil through altered environmental conditions, nutrient availability, and biotic source for microbial re-colonization. We examined the influence of fire on chemical properties and soil enzyme activities of soil for 10 months. We also characterized the soil microbial community structure through ester-linked fatty acid analysis(EL-FAME). For this study, we established five burned plots(1*1 m) and 5 unburned plots outside the margin of fire. Soil was sampled three soil cores in a each plots and composited for analysis at 1, 3, 5, 8, and 10 month after fire. The fire caused an increase in soil pH, exchangeable Ca, and Mg, organic matter, available $P_2O_5$ compared to unburned sites. The content of $NH_4-N$ in burned site was significantly higher than that of unburned site and this effect continued for 8 months after fire. There was no difference of $NO_3-N$ content in soil between burned and unburned site. Fire caused no change in acid phosphatase and arylsulfatase activities but $\beta$-glucosidase and alkaline phosphatase activities in burned site were increased compared to unburned site. Microbial biomass as estimated by total concentration of EL-FAMEs in burned sites was significantly higher than that of unburned sites at one month after fire. Burned site decreased the EL-FAMEs indicative of gram-positive bacteria and tended to increase the fatty acid associated with gram-negative bacteria at one and three months after fire. The sum of EL-FAME compound $18:2{\omega}6,9c$ and $18:1{\omega}9c$ as served fungal biomarkers was decreased in burned site compared to unburned site.

• Journal of the Korean Applied Science and Technology
• /
• v.30 no.1
• /
• pp.35-48
• /
• 2013

Biodiesel is an alternative diesel fuel which can be obtained from the transesterification of vegetable oils, animal fats and waste cooking oil. The objective of this study is to evaluate the properties of biodiesel obtained from different feedstocks (soybean, waste cooking, rapeseed, cottonseed and palm oils). The biodiesel derived from different feedstocks was analyzed for FAME (fatty acid methyl esther) content, kinematic viscosity, flash point, CFPP (cold filter plugging point) and glycerin content. The quality of biodiesel was tested according to the Korean and European standard (EN14214, requirements and test method for biodiesel fuel). The biodiesels derived from soybean, waste cooking, rapeseed and cottonseed oils contain high amount of unsaturated fatty acid, while palm biodiesel is dominated by saturated fatty acid. The fuel properties of biodiesel, such as low temperature performance, kinematic viscosity and oxidation stability are correlated with the FAME composition components in biodiesel.

• Korean Chemical Engineering Research
• /
• v.53 no.2
• /
• pp.205-210
• /
• 2015

In this paper, microalgae lipid extractions were performed using conventional organic solvent and supercritical carbon dioxide (SC-$CO_2$) for biodiesel-convertible lipid fractions. The highest levels (58.31%) of fatty acid methyl ester (FAME) content in the lipid extracted by SC-$CO_2$ was obtained, and 18.0 wt.% crude lipid yield was achieved for Bligh-Dyer method. In the SC-$CO_2$ extraction, methanol as a co-solvent was applied to increase the polarity of extract. The experimental results indicated that crude lipid yield, FAME content and yield extracted by combination of SC-$CO_2$ with methanol were 12.5 wt.%, 56.32% and 7.04 wt.%, respectively, and this method could reduce the extraction time from 2 hour to 30 min when compared to SC-$CO_2$ extraction. Therefore, SC-$CO_2$ extraction is proven to be an environmentally-friendly and an effective method for lipid extraction from microalgae.

• Korean Journal of Soil Science and Fertilizer
• /
• v.44 no.6
• /
• pp.1164-1168
• /
• 2011

This study evaluated the soil microbial communities by fatty acid methyl ester (FAME) method in soils (6 sites for immatured paddy, 9 sites for normal paddy, and 5 sites for sandy paddy) in Gyeongnam Province. The soil microbial biomass carbon content in normal and sandy paddy were 1,235 and $441mg\;kg^{-1}$, respectively, showing the soil microbial biomass carbon content in normal paddy was higher than that in sandy paddy. The soil organic matter contents $33g\;kg^{-1}$ of immatured and normal paddy were higher than sandy paddy $18g\;kg^{-1}$ (p<0.05). The communities of total bacteria and Gram-negative bacteria in normal paddy were significantly higher than those in sandy paddy (p<0.05). Total bacteria communities should be considered as a potential responsible factor for the obvious microbial community differentiation.

• Elastomers and Composites
• /
• v.39 no.2
• /
• pp.105-120
• /
• 2004

The flame retarded NBR foams were prepared with metal hydroxides and various phosphorus/nitrogen-contain ing flame retardants. The dependency of the phosphorus content on thermal properties, flame retardancy, smoke density, and foaming properties were investigated in the foams. Foaming properties and morphology of the flame retarded NBR foams with P/N flame retardants( ${\le}10 phr$) were similar to those of the foams without P/N ones but containing metal hydroxides The flame retardancy of the foams was improved with increasing the phosphorus content and char formation under combustion atmosphere. The cone-calorimeter test and LOI index were also coincided with the TGA analysis quite well. The heat release rate (HRR), total heat release (THR), and effective heat of combustion (EHC) were decreased, whereas the carbon monoxide yield was increased with increase of the phosphorus content of P/N flame retardant. The smoke density values were closely related with CO yield values obtained by the cone-calorimeter test due to the high and hard char formation.