• Clean Technology
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• v.23 no.2
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• pp.121-132
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• 2017

The increase of greenhouse gases and the concern of global warming instigate the development and spread of renewable energy and hydrogen is considered one of the clean energy sources. Hydrogen is one of the most elements in the earth and exist in the form of fossil fuel, biomass and water. In order to use hydrogen for a clean energy source, the hydrogen production method should be eco-friendly and economic as well. There are two different hydrogen production methods: conventional thermal method using fossil fuel and renewable method using biomass and water. Steam reforming, autothermal reforming, partial oxidation, and gasification (using solid fuel) have been considered for hydrogen production from fossil fuel. When using fossil fuel, carbon dioxide should be separated from hydrogen and captured to be accepted as a clean energy. The amount of hydrogen from biomass is insignificant. In order to occupy noticeable portion in hydrogen industries, biomass conversion, especially, biological method should be sufficiently improved in a process efficiency and a microorganism cultivation. Electrolysis is a mature technology and hydrogen from water is considered the most eco-friendly method in terms of clean energy when the electric power is from renewable sources such as photovoltaic cell, solar heat, and wind power etc.

• The Korean Journal of Mycology
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• v.42 no.3
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• pp.219-224
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• 2014

A gram-negative bacterium was isolated from spent substrate of Agaricus bisporus and showed marked antagonistic activity against Pseudomonas tolaasii. The bacterium was identified as Pseudomonas azotoformans by based on the cultural, biochemical and physiological characteristics, and 16S rRNA gene sequence. The isolated bacterium was saprophytic but not parasitic nor pathogenic to cultivation mushroom. The isolated bacterium for P. tolaasii cell was not sufficient for inhibition in vitro. Control efficacy of Pseudomonas azotoformans HC5 to brown blotch of P. tolaasii was 73, 78, and 71% on A. bisporus, Flammulina velutipes, and Pleurotus ostreatus, respectively. In the future, the suppressive bacterium may be useful for development of a biocontrol system.

• Korean Journal of Medicinal Crop Science
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• v.18 no.6
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• pp.389-397
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• 2010

This work was to improve antimicrobial activities of horseradish by encapsulated with edible biopolymers such as lecithin and gelatin since it has been difficult to directly use horseradish extracts into foods and food containers due to its strong and undesirable flavors. It was shown that most of the nanoparticles containing the extracts were well formed in round shape with below 400 nm diameter as well as fairly stable and less odd flavors in various pH ranges by measuring zeta potentials. The encapsulation efficiencies of nanoparticles were estimated as 66.6% and 53.4% for lecithin and gelatin, respectively. Minimal Inhibitory Concentration (MIC) of both nanoparticles against G(+), Listeria monocytogenes and G(-), Salmonella typhimurium were also measured as 79 ppm based on AIT concentrations in the extracts, whose activities were about 65% higher than the case of adding crude extract. It was also found that the nanoparticles efficiently penetrated into the cell membrane and started to destruct the cells after 6 hours cultivation under Transmision Electron Microscopy observation. These results prove that the nano-encapsulation of the horseradish extracts can be employed to directly treat into the foods and food containers for antimicrobial purposes with the aids of aerosolization system, by using small amounts of the extracts and having less flavors due to masking effects of nanoparticles.

• Journal of Microbiology and Biotechnology
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• v.23 no.4
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• pp.534-538
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• 2013

The effects of lights with different wavelengths on the growth and the yield of extracellular polysaccharides of Nostoc flagelliforme cells were investigated in a liquid cultivation. N. flagelliforme cells were cultured for 16 days in 500 ml conical flasks containing BG11 culture medium under $27{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ of light intensity and $25^{\circ}C$ on a rotary shaker (140 rpm). The chlorophyll a, phycocyanin, allophycocyanin, and phycoerythrin contents in N. flagelliforme cells under the lights of different wavelengths were also measured. It was found that the cell biomass and the yield of polysaccharide changed with different wavelengths of light. The biomass and the yield of extracellular polysaccharides under the red or violet light were higher than those under other light colors. Chlorophyll a, phycocyanin, and allophycocyanin are the main pigments in N. flagelliforme cells. The results showed that N. flagelliforme, like other cyanobacteria, has the ability of adjusting the contents and relative ratio of its pigments with the light quality. As a conclusion, N. flagelliforme cells favor red and violet lights and perform the complementary chromatic adaptation ability to acclimate to the changes of the light quality in the environment.

• Korean Journal of Microbiology
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• v.28 no.1
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• pp.55-64
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• 1990

Cell volume and DNA contents of the fusants were similar to those of parents. Genetic stability of the fusants was increased when they were cultured on minimal medium (MM) rather than on complete medium (CM), and the fusants were stabilized by subculturing 7 generations each 7 day on MM agar. The finally selected fusants after being cultured for 6 months on CM were stable without segregation. The fusants could also form nuclein and ascospores, and show red and pink colors by the test of TTC colorization. Assimilability and fermentability of carbon sources of the fusants were similarto those of parents. The tolerance of KCl, NaCl, sodium propionate and cycloheximide showed the traits of one strain of parents. When the fusants were cultured for 72 hr and 60 hr in the medium containing 20% glucose and sucrose, respectively, the yield of ethanol for FWKS 260 was reached to 9.6 v/v% and 9.8v/v%, respectively. The sensitive strain Kyokai 7 was found to be killed entirely after cultivation of 48 hr by the killer toxin from the fusants. The recipient S 29 and Kyokai 7 were found to have neither L nor M dsRNA plasmid. However, K 52 and fusants had both L and M dsRNA plasmid of 4.7 kb and 2.5 kb, respectively. The curants treated by heat and cycloheximide did not contain M dsRNA plasmid, but had large amounts of L dsRNA plasmid of those of killer yeasts.

• The Korean Journal of Mycology
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• v.34 no.1
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• pp.1-6
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• 2006

In order to select a suitable bioreactor type for the submerged cultivation of Ganoderma applanatum, both growth characteristics and polysaccharides production were compared among four different types of bioreactor. These include an external-loop type air-lift bioreactor (ETAB), a balloon type air bubble bioreactor (BTBB), a column type air bubble bioreactor (CTBB) and a stirrer type bioreactor (STB). The mycelial biomass produced from the reactors were in decreasing order: ETAB ($7\;g/{\ell}$) > BTBB ($6.2\;g/{\ell}$) > STB ($6\;g/{\ell}$) > CTBB ($5\;g/{\ell}$). Maximal soluble exopolysaccharides ($1\;g/{\ell}$) and endopolysaccharides (2.7%) were also obtained from ETAB. Thus, the ETAB was most suitable for submerged culture of G applanatum mycelium. Based on the results, ETAB was chosen for further detailed study. The most effective aeration rate for the mycelial growth in ETAB ranged from 0.05 to 0.1 vvm. For the maximal production, the mycelium at the initial growth stage needed low aeration rate to reduce cell damages by fluid flow. However, as the mycelia grew, the culture became viscous and thus needed higher aeration. The molecular weight of exopolysaccharides obtained from the culture grown in ETAB was higher than that from the culture grown in other bioreactors.

• Journal of Marine Bioscience and Biotechnology
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• v.8 no.1
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• pp.18-23
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• 2016

It is important to design photobioreactor by cheap material for economical microalgal biomass production. In this study, two types of marine photobioreactors (MPBR), made by either polyvinyl chloride (MPBR-PVC) or high density poly ethylene (MPBR-HDPE), are used and performance of these were compared. Tetraselmis sp. KCTC 12236BP is a green marine alga that isolated from Ganghwa Island, Korea, and the strain was used for marine cultivations using MPBR-PVC and MPBR-HDPE. The cultivations were performed three times in the spring season of 2012 using MPBR-PVC and of 2013 using MPBR-HDPE in the coastal area of Young Heung Island. As the results, MPBR-PVC shows higher biomass productivities than MPBR-HDPE, due to its high light transmittance. In the cultivations using MPBR-PVC, the average sea water temperature was $11.5^{\circ}C$ during the first experiment and $16.5^{\circ}C$ during the second and third experiments. Average light intensities during three times for experiments were 407.5, 268.1 and $273.0{\mu}{\cdot}E{\cdot}m^{-2}{\cdot}s^{-1}$, respectively. The maximum fresh cell weight and average biomass productivity were $1.2g{\cdot}L^{-1}$ and $0.12g{\cdot}L^{-1}{\cdot}day^{-1}$. These results showed that Tetraselmis sp. KCTC12236BP were adapted well with the environmental conditions from ocean, and grow in the MPBR-PVC and MPBR-HDPE.

• Korean Journal of Agricultural and Forest Meteorology
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• v.18 no.4
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• pp.298-306
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• 2016

Planting date shift is one of the means of adapting to climate change in Kimchi Cabbage growers in major production areas in Korea. This study suggests a method to estimate the potential yield of Kimchi Cabbage based on daily temperature accumulation during the growth period from planting to maturity which is determined by a plant phenology model tuned to Kimchi Cabbage. The phenology model converts any changes in the thermal condition caused by the planting date shift into the heat unit accumulation during the growth period, which can be calculated from daily temperatures. The physiological maturity is estimated by applying this model to a variable development rate function depending either on growth or heading stage. The cabbage yield prediction model (Ahn et al., 2014) calculates the potential yield of summer cabbage by accumulating daily heat units for the growth period. We combined these two models and applied to the 1km resolution climate scenario (2000-2100) based on RCP8.5 for South Korea. Potential yields in the current normal year (2001-2010) and the future normal year (2011-2040, 2041-2070, and 2071-2100) were estimated for each grid cell with the planting dates of July 1, August 1, September 1, and October 1. Based on the results, we divided the whole South Korea into 810 watersheds, and devised a three - dimensional evaluation chart of the time - space - yield that enables the user to easily find the optimal planting date for a given watershed. This method is expected to be useful not only for exploring future new cultivation sites but also for developing cropping systems capable of adaptation to climate change without changing varieties in existing production areas.

• KSBB Journal
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• v.20 no.1 s.90
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• pp.26-33
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• 2005

The effects of carbon sources for exopolysaccharide production during batch cultivation of an Enterobacter sp. isolated from the composter were investigated. The highest amount of exopolysaccharide was obtained when lactose was used as carbon source. Lactose in medium was converted into glucose and galactose. Glucose was metabolized fast and was completely consumed, but about $20\%$ of lactose was accumulated as galactose. On the other hand, enzyme activity was about $350\~450$ unit with the increase of lactose concentration. Thus, it was considered that the exopolysaccharide might be produced in the course of that lactose was hydrolyzed into glucose and galactose by $\beta-galactosidase$ with respect to that enzyme activity on lactose hydrolysis was accorded to the exopolysaccharide production. When glucose and galactose were added to lactose medium, respectively, it could be considered that glucose was as a repressor and galactose was as a inducer for $\beta-galactosidase$ synthesis even though the mechanisms were not elucidated. The increase of lactose concentration was almost ineffective to the specific growth rate $(0.133\~0.151\;hr^[-1})$ but showed the difference in the biomass content. The higher carbon source concentration, the more residual sugar remained. It was assumed that the optimum lactose concentration for exopolysaccharide production was $30\~70g/L.$ On the other hand, it was considered that the nitrogen acted as growth limiting nutrients to the cell growth. In the cases of 30 and 70 g/L of the fixed carbon concentrations, the increase of the nitrogen sources concentration caused a remarkable increase within the range of $0.059\~0.225\;hr^{-1}$ and $0.141\~0.237hr^{-1}$ of the specific growth rate, respectively, while there was no significant difference in biomass.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.4
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• pp.486-489
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• 2009

This study was performed to evaluate contents and estimated availabilities of major minerals (Ca, P, K, Mg) in soybean sprouts. Two different sampling parts (cotyledon and hypocotyl), and three culture periods (1, 3, and 5 days) were evaluated. Results indicated that Mg (99.11%) from cotyledon for 5 days culture period was significantly higher than Ca (98.34%), P (97.67%), and K (98.70%). Percent average Mg estimated availability of 5 days cultured hypocotyl was also significantly higher than that of Ca (77.79%), P (91.91%), and K (96.80%). Therefore, the current results indicate that decreased Ca estimated availability in hypocotyl was time dependent and the cotyledon may be the better source for the estimated availability of major minerals than the hypocotyl of soybean sprouts because more than 90% of the major minerals was estimated availability.