• Korean Journal of Food Science and Technology
• /
• v.32 no.2
• /
• pp.284-290
• /
• 2000

A marine bacterium Bacillus cereus ASK202 showing a high agar degrading activity, was incubated in the culture medium containing agar. After incubation for 30 hr, the productivity of agarase in the culture broth reached to maximum value (160.8 units/L). As the results of TLC and HPLC analysis, agarooligosaccharides (degrees of polymerization 2, 4 and 6) were produced from the hydrolysis of agar by using the crude agarase. Physical and chemical properties of agarooligosaccharides were compared with the manufactured products of other oligosaccharides (fructooligosaccharide; isomaltooligosaccharide; maltotetraoligosaccharide) and agarooligosaccharides showed higher viscosity, higher contents of oligosaccharides, higher stability at low pH's and higher temperatures, and lower sweetness than other oligosaccharides.

• Journal of Biomedical and Translational Research
• /
• v.19 no.4
• /
• pp.103-109
• /
• 2018

Aspergillus luchuensis 34-1 was inoculated into wheat pellets with different conditions of raw materials to produce nuruk. The degree of substrate reactivity improvement of steam treated raw materials compared with that of non-heat treated was analyzed. The water content of the pellet was adjusted to 25% and 35%, and steam treatment for 10 minutes improved the substrate reactivity at 2.1-fold and 3.1-fold, and sterilization was also possible. The characteristics of improvement pellet nuruk were investigated according to the degree of crushing and water content of raw materials according to the temperatures and humidities ($23^{\circ}C$, $30^{\circ}C$ and RH 60%, RH 80%). The pH of the pellet nuruk was higher depending on the temperature, humidity and moisture content of the koji were lower, and the pH of the flour-pellet nuruk was lower than that of 2 mm milling wheat-pellet nuruk according to milling degree. It can be seen that the milling degree affects the growth of mold. The acidity and amino acid were generally higher as fermentation time increased. Also, the higher the incubation temperature, humidity and moisture content, the higher the value. Glucoamylase activity was significantly the highest in moisture content 35% D2b nuruk, cultured at $30^{\circ}C$ and 80% RH for 38 hours. This is higher than the previous reports on glucoamylase of rice-koji or commercial nuruk using fungi isolated from traditional nuruk. From these study, it is expected that making of improvement pellet nuruk would save the fermentation time considerably compared with traditional nuruks.

• Microbiology and Biotechnology Letters
• /
• v.47 no.1
• /
• pp.54-63
• /
• 2019

Rubus coreanus Miquel (RCM), also known as Korean blackberry or bokbunja, is used as a South Korean traditional medicine to treat acne and inflammatory skin conditions. The antimicrobial activity of RCM root and its active compounds remain unclear. In this study, we prepared a 50% ethanol fraction, ethyl acetate fraction, and acid-treated ethyl acetate fraction (aglycone fraction) of RCM root, and evaluated antibacterial activities against the skin pathogens Staphylococcus aureus, Pseudomonas acnes, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa. In a paper disc assay, all fractions of RCM root showed antimicrobial activities against the five skin pathogens. The ethyl acetate fraction displayed 6-, 12-, and 2-fold higher minimal inhibitory concentration (MIC) than the 50% ethanol fraction against S. aureus, E. coli, and P. acnes, respectively. The aglycone fraction displayed 2-fold higher MIC than methyl paraben against P. acnes, S. aureus, E. coli, and P. aeruginosa. The ethyl acetate fraction displayed a minimal bactericidal concentration (MBC) similar to that of methyl paraben, and the aglycone fraction showed 2- to 4-fold higher MBCs than those of methyl paraben. In particular, the ethyl acetate fraction was not cytotoxic and showed thermal stability after incubation at high temperatures ($60-121^{\circ}C$). Finally, the ethyl acetate fraction was separated and four components were identified: procyanidin C, propelagonidin dimer, ellagic acid, and methyl ellagic acid acetyl pentose. The compounds showed high antibacterial activities. These results suggest that RCM root is potentially applicable as a natural preservative in cosmetics.

• Korean Chemical Engineering Research
• /
• v.61 no.2
• /
• pp.278-286
• /
• 2023

The present work evaluated the production of biohydrogen under mesophilic and thermophilic conditions through dark fermentation of palm oil mill effluent (POME) in batch mode using the design of experiment methodology. Response surface methodology (RSM) was applied to investigate the influence of the two significant parameters, POME concentration as substrate (5, 12.5, and 20 g/l), and volumetric substrate to inoculum ratio (1:1, 1:1.5, and 1:2, v/v.%), with inoculum concentration of 14.3 g VSS/l. All the experiments were analyzed at 37 ℃ and 55 ℃ at an incubation time of 24 h. The highest chemical oxygen demand (COD) removal, hydrogen content (H₂%), and hydrogen yield (HY) at a substrate concentration of 12.5 g COD/l and S:I ratio of 1:1.5 in mesophilic and thermophilic conditions were obtained (27.3, 24.2%), (57.92, 66.24%), and (6.43, 12.27 ml H₂/g COD_rem), respectively. The results show that thermophilic temperature in terms of COD removal was more effective for higher COD concentrations than for lower concentrations. Optimum parameters projected by RSM with S:I ratio of 1:1.6 and POME concentration of 14.3 g COD/l showed higher results in both temperatures. It is recognized how RSM and optimization processes can predict and affect the process performance under different operational conditions.

• Korean Journal of Environmental Agriculture
• /
• v.42 no.4
• /
• pp.324-330
• /
• 2023

This study was conducted to determine the dormancy types and optimal germination conditions of Prunus mandshurica seeds. The pericarp of P. mandshurica seeds was presumed to be the reason for their poor water absorption. After the pericarp was removed with a razor blade, germination was observed to be less than 20.0% at all temperatures except at 5℃, suggesting the presence of physiological dormancy. Germination gradually increased at 5℃ after the removal of seed coat, reaching a final germination rate of 86.7% at 14 weeks of incubation. Based on these results, P. mandshurica seeds have a physiological dormancy. When seeds with removed pericarp were subjected to cold stratification, the germination percentage (rate) in the control group was low even at 16 weeks; however, the germination percentages in the 4, 8, and 12-week cold stratification groups were notably high with 93.3, 73.3, and 100.0%, respectively. The control group in the GA3 treatment experiment with seed coats removed showed minimal germination, but at 10 weeks, the germination percentage rose to 98.3% when treated with GA3 at 100 mg/L. Thus, it is necessary to scarify or completely remove the pericarp of P. mandshurica seeds to promote germination. After pericarp removal, it is important to subject the seeds to cold stratification at 5℃ for at least 4 weeks or treat them with GA3 at 100 mg/L.

• Journal of Life Science
• /
• v.19 no.5
• /
• pp.581-586
• /
• 2009

Bell pepper plants (Capsicum annuum cv. Plenty) were grown under low night temperatures (LNT: day/night temperature of $28/13^{\circ}C$) and optimum night temperatures (ONT: day/night temperature of $28/20^{\circ}C$) in growth chambers. Pollen grains were collected from plants in the growth chamber and incubated at 10, 15, 20, 25, and $30^{\circ}C$. After 24 hr incubation, in both ONT and LNT, the highest percent pollen germinations were observed at $25^{\circ}C$ followed by germinations at $30^{\circ}C$. Percent pollen germination at $25^{\circ}C$ was 42% in ONT - two times higher than in LNT at 21%. Pollen tube length was much longer at ONT than at LNT, regardless of incubation temperature. Compared with other treatments, earlier and quicker pollen tube elongation was observed in ONT pollen grains incubated at $25^{\circ}C$. To find pollen viability in plant growing conditions, pollen grains were incubated in LNT ($28/13^{\circ}C$) and ONT ($28/20^{\circ}C$) growth chambers for 24 hr. Petri-dishes with pollen grains were put in the growth chambers at the beginning of the night condition. Pollen grains in the LNT growth chamber did not germinate at night ($13^{\circ}C$), but began to germinate when the day condition ($28^{\circ}C$) started. Pollen grains in the ONT condition, however, started germinating from the early night ($20^{\circ}C$) and germination continued during the day ($28^{\circ}C$). Plants in LNT showed increased flower stalk length, ovary diameter, stamen length, flower weight, and fruit length. LNT conditions did not impair seed set. There were no differences in seed sets between fruits at LNT and ONT. Normal seed sets in LNT show that fertilization may be completed during daytime. However, further investigation is needed to find what extent of temperature stress causes malformed and/or parthenocarpic fruits in this bell pepper.

• Korean journal of applied entomology
• /
• v.43 no.4 s.137
• /
• pp.297-304
• /
• 2004

The development of Aphidoletes aphidimyza, an aphidophagous gall midge, was studied at various constant temperatures ranging from 15 to $35^{\circ}C$, with $65{\pm}5\%$ RH, and a photo-period of 16L:8D. When A. aphidimyra was fed either on Aphis gossypii or Myzus persicae, it took 43.9 and 44.5 days, respectively, to develop from egg to pupa at $15^{\circ}C$, whereas at $25^{\circ}C$, 14.3 and 15.8 days. The developmental zero was 10.7 and $10.0^{\circ}C$, respectively, while the effective accumuative temperatures were 210.8 and 245.5 day-degrees. The nonlinear shape of temperature-dependent development, shown by A. aphidimyza when fed on either species of the aphids, was well described by the modified Sharpe and DeMichele model. When distribution model of completion time of development for each growth stage was expressed as physiological age and fitted to the Weibull fuction, the completion time of development gradually shortened from egg to larva, and to pupa. In addition, the coefficient of determination $r^2$ ranged between 0.86-0.93 and 0.85-0.94, respectively providing a good approximation of cumulative developmental rates. The life span of adult was 8.7 and 9.2 days at $15^{\circ}C$, and 3.1 and 2.7 days at $30^{\circ}C$, respectively. Egg incubation period was relatively short at $35^{\circ}C$ but hatchability was less than $50\%$ and the mortality of the larva at $35^{\circ}C$ reached $100\%$. At $30^{\circ}C$, the time of development lengthened and the adult longevity was short suggesting ill effect of high temperatures. Even though the life span of adults at $15^{\circ}C$ was relatively long, none moved freely in the rearing cage and no oviposition occurred. Accordingly, in case A. aphidimyza is adopted to suppress phytophagus aphid populations, it could be applicable to cropping systems with ambient temperatures above $20^{\circ}C$ and below $30^{\circ}C$. Within this range, A. aphidimyza adults was observed to be active and oviposit fully.

• Research in Plant Disease
• /
• v.22 no.2
• /
• pp.72-80
• /
• 2016

Gummy stem blight, caused by the fungus Didymella bryoniae, is major disease of watermelons worldwide. The objective of the present study was to establish an efficient screening system to identify watermelon resistant to D. bryoniae. An GSB3 isolate was prepared from a watermelon plant showing typical symptoms of gummy stem blight in Haman-gun and identified as D. bryoniae based on molecular analysis of internal transcribed spacer sequence. A simple mass-production technique of inoculum was developed based on spore production of D. bryoniae GSB3 under several incubation conditions and their virulence on watermelon plants. Resistance degrees of 22 commercial watermelon cultivars to the GSB3 isolate were evaluated. Among them, four watermelon cultivars showing different degree of resistance response were selected for further study. Development of disease on the cultivars according to various conditions including inoculum concentrations, incubation periods in dew chamber, and incubation temperatures was investigated. From the results, we suggest an efficient screening method for resistant watermelon cultivars to gummy stem blight. Seeds of watermelon cultivar are sown and grown in a greenhouse until plant stage of 2-fully expanded leaves. Seedlings are inoculated with D. bryoniae by spraying spore suspension of the fungus at a concentration of $5.0{\times}10^5spores/ml$. The infected plants are incubated in humidity chamber at $25^{\circ}C$ for 48 hours and then transferred to a growth chamber at $25^{\circ}C$ and 80% relative humidity with 12-hour light a day. Three to four days after inoculation, disease severity of the plant are measured using percentage of infected leaf area.

• Journal of the Microelectronics and Packaging Society
• /
• v.12 no.4 s.37
• /
• pp.307-313
• /
• 2005

Electromigration behavior in the Sn96.5Ag3.0Cu0.5 solder lines was investigated and compared Sn96.5Ag3.0Cu0.5 with eutectic SnPb. Measurements were made for relevant parameters for electromigration of the solder, such as drift velocity, threshold current density, activation energy, as well as the product of diffusivity and effective charge number (DZ$\ast$). The threshold current density were measured to be $2.38{\times}10^4A/cm^2$ at $140^{\circ}C$ and the value represented the maximum current density which the SnAgCu solder can carry without electromigration damage at the stressing temperatures. The electromigration energy was measured to 0.56 eV in the temperature range of $110-160^{\circ}C$. The measured products of diffusivity and the effective charge number, DZ$\ast$ were $3.12{\times}10^{-10} cm^2/s$ at $110^{\circ}C$, $4.66{\times}10^{-10} cm^2/s$ at $125^{\circ}C$, $8.76{\times}10^{-10} cm^2/s$ at $140^{\circ}C$, $2.14{\times}10^{-9}cm^2/s$ at $160^{\circ}C$ SnPb solder existed incubation stage, while SnAgCu did not have incubation stage. It was thought that the diffusion mechanism of SnAgCu was different from that of SnPb.

• Korean Journal of Soil Science and Fertilizer
• /
• v.45 no.4
• /
• pp.657-663
• /
• 2012

To evaluate effects of water temperatures on nutrient releases of submerged plants in lake reservoir, COD, T-N and T-P releases of submerged plants were investigated for 60 days under different incubation temperatures ($5^{\circ}C$ and $25^{\circ}C$) in columns. The amounts of COD releases by Carex dimorpholepis were $60.4mg\;L^{-1}$ at $5^{\circ}C$ and $78.0mg\;L^{-1}$ at $25^{\circ}C$. In Miscanthus sacchariflorus, the amounts of COD releases were $62.5mg\;L^{-1}$ at $5^{\circ}C$ and $70.5mg\;L^{-1}$ at $25^{\circ}C$. The amounts of T-N releases in Carex dimorpholepis at $5^{\circ}C$ and $25^{\circ}C$ were 45.8 and $60mg\;L^{-1}$, respectively. In Miscanthus sacchariflorus, the amounts of T-N releases were $55.7mg\;L^{-1}$ at $5^{\circ}C$ and $61.0mg\;L^{-1}$ at $25^{\circ}C$. At $5^{\circ}C$, the amounts of T-P releases in Carex dimorpholepis and Miscanthus sacchariflorus were 5.65 and $7.10mg\;L^{-1}$, respectively. At $25^{\circ}C$, the amounts of T-P releases in Carex dimorpholepis and Miscanthus sacchariflorus were 8.70 and $8.18mg\;L^{-1}$, respectively. In the column experiment, the amounts of COD, T-N and T-P releases by submerged plants at $25^{\circ}C$ were generally higher than those at $5^{\circ}C$.