• KSBB Journal
• /
• v.19 no.2
• /
• pp.154-158
• /
• 2004

Recycled packed-bed reactor emploring immobilized microorganism was suggested in this paper for efficient denitrification. In the batch reactor, the effects of initial oxidation-reduction potential and nitrate concentration on denitrification were investigated. As the initial oxidation-reduction potential was decresed to -70 mV from ＋40 mV, the removal rate of nitrate was increased to 3.33 from 1.25 m9 NO$_3$$\^$-/-N/min under the experimental conditions. As the initial nitrate-N concentraion was increased to 200 mg/l, the removal rate of nitrate was proportional to the concentration of nitrate. When the concentration of nitrate-N was 400 mg/min, nitrite was detected, and when the initial nitrate-N concentration was reached at 1,000 mg/l, it took longer time for the complete nitrate removal. In order to decrease the initial oxidation-reduction potential and the nitrate-N concentration in the feed stream, the effluent was recycled to the influent stream in the packed-bed reactor. In the case of recycling, the initial oxidation-reduction potential was decreased to 30 mV from 150 mV, and the initial nitrate concentration could be decreased to 85 from 120 mg NO$_3$$\^$-/-N/l. As the result of recycling, the removal rate of nitrate was increased to 91.7% from 49.2%.

• KSBB Journal
• /
• v.22 no.2
• /
• pp.67-72
• /
• 2007

This study investigates the optimal method of administrating 5-aminolevulinic acid (5-ALA) in the context of fluorescence detection by analyzing protoporphyrin IX (PpIX) fluorescence in the cultured normal and cancer cells. 5-ALA was injected as a photosensitizer to the lung cancer cells (A549, NCI-H460) and normal lung cells (HeI299). Hel299, A549, and NCI-H460 cells were incubated with various concentrations of 5-ALA ($0\sim800{\mu}g/mL$). The accumulation of PpIX induced by 5-ALA was observed in A549, NCI-H460 and Hel299 cells. The cell viability was estimated by means of the MTT assay. Formation of PpIX was measured by fluorescence spectroscopy. Especially, formation of PpIX in cancer cells was higher than normal cells. This study suggests that the difference of PpIX induced in normal and cancer cells treated with 5-ALA may use by means of fluorescence diagnosis for cancer.

• KSBB Journal
• /
• v.15 no.5
• /
• pp.482-488
• /
• 2000

The Fab fraction of PDC-E2 specific human monoclonal antibody was produced using recombinant E. coli, and the effects of glucose and acetate were investigated to develop an optimal strategy for recombinant human antibody production. Higher glucose concentration in the culture media resulted inn higher cell growth and glucose consumption rate, which in turn resulted in an increased acetate production rate. When glucose was depleted, cells began to consume acetate as an energy source, and this consumption rate depended on the glucose concentration. When the residual glucose concentration was high, the accumulation of acetate was accelerated due to an increase in the acetate production rate and a decrease in the acetate consumption rate. Futhermore, it was found that a high accumulation of acetate, accompanied by a high glucose concentration, inhibited human antibody formation; the critical acetate concentration was $0.6g/\ell$. During production, a high glucose concentration enhanced cell growth, but inhibited antibody formation due to catabolic repression. Therefore, it is important to keep the concentration of both glucose and acetate as low as possible to increase antibody production after induction. Accordingly, it is important to accurately control the concentration of glucose and acetate in the culture media to obtain high cell densities and high productivity levels of recombinant human antibody.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.18 no.4
• /
• pp.266-276
• /
• 2013

The ocean is the largest reservoir of carbon in the climate system. Atmospheric $CO_2$ is efficiently transferred to the deep ocean by a process called the biological carbon pump: photosynthetic fixation of $CO_2$ at the sea surface and remineralization of sinking organic carbon at depths are main causes for the vertical contrast of carbon in the ocean. The sequestered carbon to the deep ocean returns to the sea surface by ocean circulation. Part of the upwelled $CO_2$ leaks into the atmosphere through air-sea gas exchange. It has been suggested that the air-sea partitioning of carbon has varied in concert with the glacial-interglacial climate variations, due partly to changes in ocean circulation. In this review paper, we briefly summarize key concepts of the oceanic carbon pump. We also discuss the response of the air-sea carbon partitioning to change in ocean circulation in the context of the glacial-interglacial climate change.

• Journal of Bio-Environment Control
• /
• v.21 no.4
• /
• pp.452-458
• /
• 2012

Rare earth elements fertilizer and Ca were sprayed on eight-year-old 'Fuji'/M.9 apple trees during two consecutive seasons, and fruit quality was quantified at harvest and 5-month long storing in a commercial cooling house at $4^{\circ}C$ and 80~85% RH. In the first season, single-sprayed of rare earth elements fertilizer showed appreciable accumulations of its elements (La, Pr, Gd, and Nd) in the fruit. In the following season, application of higher doses accumulated higher amount, indicating that the accumulation of rare earth elements was dose-dependent. However, rare earth elements did not affect the accumulations of Ca, Mg, and K in 'Fuji' apple fruit showed that there was no interaction between rare earth elements and these macronutrients. Double-spray of 0.2% rare earth elements increased fruit redness at harvest and had exhibited better color. Although at harvest it did not show significant effects on fruit weight, pulp firmness and titratable acidity (TA), but had pronounced effects on inhibiting fruit softness and retarded decrease of TA during storing. Furthermore, it reduced respiration rate and inhibited ethylene production during storing indicated that rare earth elements may be an alternative for prolonging the shelf life of 'Fuji'/M.9 apple fruit.

• Journal of Plant Biotechnology
• /
• v.42 no.1
• /
• pp.34-42
• /
• 2015

This study was conducted to investigate the productivity of biomass and antioxidant compounds in Polygonum multiflorum by culturing explants in air-lift bioreactor containing Murashige and Skoog (MS) medium, by adding different concentrations of auxins [indole-3-butyric acid (IBA) and naphthalene acetic acid (NAA)], sucrose, methyl jasmonate (MeJA), and salicylic acid (SA). Results of this study revealed that the explants culturing on the medium supplemented with $9.84{\mu}M$ IBA and 50 g/L sucrose were observed to have higher productivity of biomass and bioactive compound than other treatments used. Thus, we expect that these results will be helpful for large-scale production of biomass and antioxidant compounds from Polygonum multiflorum.

• KSBB Journal
• /
• v.21 no.3
• /
• pp.171-174
• /
• 2006

To clarify the usefulness of fluorescent diagnosis for cancer, We investigated the optimal method of administrating 5-aminolevulinic acid(5-ALA) by analyzing fluorescence signal of Protoporphyrin IX(PpIX) in the cultured normal and cancer cells. 5-ALA was injected as a photosensitizer to the cervico-uterine cancer cell line(HeLa) and in normal liver cells(Chang). Chang and HeLa cells were incubated with various concentrations of 5-ALA($0-800{\mu}g/ml$). The accumulation of PpIX induced by 5-ALA was in HeLa and Chang cells. The cell viability was measured by MTT assay. The optimal concentration of ALA that induced maximum levels of PpIX was $50{\mu}g/ml$ in HeLa cell cultured for 24 hours after 5-ALA injection. Fluorescence of PpIX in HeLa cell was excited at a wavelength(${\lambda}$=410 nm) and showed an emission spectrum at 602.3 nm, 659.9 nm which could be related to the PpIX generation induced by the applied 5-ALA. The experimental results showed that fluorescence signal of PpIX was proportional to the concentration of 5-ALA in cancer cells, but measured with low concentration in normal cells.

• The Korean Journal of Malacology
• /
• v.24 no.3
• /
• pp.253-260
• /
• 2008

A total of 15 different residues of polycyclic aromatic hydrocarbons (PAHs) in each 20 samples of Pacific oysters, dried laver and rockfish obtained from seafood markets were analyzed. The prevalence of samples in which more than one PAH residues were found was 75% in oyster, 35% in rock fish hepatopancreas, 0% in rockfish muscle and laver, respectively. To estimate factors contributing to this residue level difference among organisms, tissue concentrations were analyzed after exposing three organisms to phenanthrene, a representative PAH, with concentration of 0.01 or $0.1{\mu}g/mL$ for 2 weeks. Phenanthrene levels after exposure were higher in the oyster digestive gland, laver and rockfish hepatopancreas, but were lower in the oyster whole meat or rockfish muscle. This finding disproved that any close relationship between the residue difference of market samples and concentrating properties of PAHs. The second possible factor analyzed was total lipid contents in the three organisms. Although higher lipid level in hepatopancreas of rockfish may contribute accumulation of PAH residues in the rockfish, lipid factor did not affect to PAH levels in other organism samples. Activity of 7-ethyoxyresorufin-O-deethylase (EROD), a kind of cytochrome $P_{450}$ enzyme, was measured to evaluate the eliminated amount of PAHs through metabolism. The higher EROD activity in rockfish, compared to that in oyster, was likely to contribute to the lower PAH residues in the rockfish. More factors, such as different exposure history, organisms' ability to escape, ingestion through prey organisms, and post-harvest loss, should be studied in the future.

• Journal of Korean Society of Environmental Engineers
• /
• v.28 no.4
• /
• pp.355-361
• /
• 2006

In this study, effects of influent C/N(COD/Nitrate) ratio and dissolved oxygen(DO) concentration on biological nitrate removal from groundwater were investigated in the fixed-type biofilter. Influent nitrate of 30 mg/L was removed completely by biological denitrification at the C/N ratio of 10 and 4.0, while residual nitrate of 5 mg/L occurred at the C/N ratio of 2.0, which resulted from deficiency of organic electron donor. Furthermore, nitrite was accumulated up to about 5 mg/L as the C/N ratio decreased to 2.0. Increase in DO concentration also inhibited denitrification activity at the relatively high C/N ratio of 5.0, which decreased the nitrate removal efficiency. Although the influent DO concentration was reduced as low as 0.3 mg/L using sodium sulfite($Na_2SO_3$), effluent nitrite was up to 3.6 mg/L. On the other hand, nitrate was completely removed without detection of nitrite at the DO concentration of 0.3 mg/L using nitrogen gas($N_2$) sparging. The organic matter for denitrification in biofilter were in the range from 3.0 to $3.5gSCOD/g{NO_3}^--N$, while utilized these values increased at the high DO concentration of 5.5 mg/L. In addition to the high DO concentration and the low influent C/N ratio, DO control by chemical such as sodium sulfite affected on biological denitrification, which resulted in the reduction of nitrate removal efficiency and nitrite build-up in a biofilter.

• KSBB Journal
• /
• v.11 no.2
• /
• pp.246-253
• /
• 1996

An obligatory methanotroph Methylosinus trichosporium OB3b was cultivated for the production of poly-${\beta}$-hydroxybutyric acid(PHB) in shake-flask using liquefied natural gas(LNG) as the sole source of carbon and energy. The maximal specific growth rate decreased by 40% using LNG compared with that obtained with pure methane. This is attributed to the inhibition by ethane and propane presents in the LNG as impurities. For the production of PHB, two-stage culture separating the production stage from the growth stage was carried out. PHB accumulation was observed after switching nutrient-sufficient to nutrient-limited condition of non-carboneous component (NO3-, PO43-, K+, Na+, Fe2+, or Mg2+). The limitation of K+ or Mg2+ resulted in relatively high PHB content, but the highest content was obtained by nitrate limitation. The optimal pH and temperature for PHB accumulation was 7.0 and $30^{\circ}C$. Under the optimal condition the maximal PHB content was about 45% after 4-day cultivation.