• Korean Journal of Microbiology
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• v.18 no.4
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• pp.155-160
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• 1980

Microorgansims utilizing anionic detergent as their carbon and sulfur sources were isolated from soils and sewages. Alkyl benzene sulfonate (Hiti) and sodium dodecyl sulfonate (SDS) were the detergent compound tested. Three of these isolated microorganisms were identified as Pseudomonas spp. and the others asKlbsiella, Enterobacter and Acinetobacter. Biodegradation rate of the detergents and growth rate of Acinetobacter Strain II-8, Pseudomonas strain H-3-1 and 554 among six isolated microorganisms were investigated with colorimetric, warburg manometric, and ultraviolet absorption analyses. By performance of 4 serial successive tranfer to new culture broth for the purpose of adaptation method, ABS and SDS could be degraded to far more than 40%-60% and 70%-75%, respectively. However the employment of nonadaptation method, ABS and SDS were degraded to 30%-45% and 45%-65%, respectively. In another words, detergents degradation ability was increased to a certain extent by successive transfer to the new minimal media. We would conclude that the development of adaptation was effective in the removal of recalcitrant compounds.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.1
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• pp.52-60
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• 2004

The optimized in vitro culture system was investigated for improvement of regeneration efficiencies by observing the responses of scutella-derived callus of Korean rice (Oryza sativa L.). Large variations of callus induction (43.9-93.9%) and shoot regeneration (0-88.7%) were observed among the rice cultivars depending on medium. However, shoot regeneration was significantly improved by selected utilization of basal medium, growth regulators, and carbon sources. N6 basal medium was more efficient for embryogenic callus induction than MS or LS basal medium, while MS was superior to N6 for shoot regeneration. The calli of highly regenerative cultivars grew faster and showed higher rates of green tissue formation (GT) and shoot regeneration (SR) and lower rate of callus browning (CB) than those of recalcitrant cultivars. Although a higher level of kinetin stimulated the GT and SR in highly regenerative cultivars, $10\textrm{mgL}^{-1}$ kinetin generally suppressed the GT and SR, while CB was accelerated compared to $2\textrm{mgL}^{-1}$ kinetin. Additional benefits of sorbitol combined with maltose (or sucrose) under $5\textrm{mgL}^{-1}$ kinetin were certainly confirmed on regeneration efficiencies compared to sucrose alone as carbon source and osmotic regulator. This combination showed high rate of GT and SR with multiple shoots while low rate of CB. With MSRK5SM-Pr medium ($5\textrm{mgL}^{-1}$ kinetin, 3% sorbitol, 2% maltose, $500\textrm{mgL}^{-1}$ proline), the regeneration efficiencies of total 17 out of 24 cultivars were practically improved 160% on average compared to MSRK2S ($2\textrm{mgL}^{-1}$ kinetin, 3% sucrose) control medium. Especially, the medium was most effective to the cultivars showing a medium level of regenerability such as Daesanbyeo and Dongjinbyeo and Suwon477, enhancing efficiencies more than 300-600% compared to MSRK2S medium.

• Korean Journal of Microbiology
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• v.47 no.2
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• pp.137-142
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• 2011

$TiO_2$-coated bamboo activated carbon has been prepared and utilized under UV irradiation as a pretreatment method for an effective biodegradation of the recalcitrant polyaromatic hydrocarbons (PAHs). The anatase $TiO_2$ was successfully coated on the bamboo activated carbon (AC) and it showed the highest photoactivity against methylene blue. In the absence of the PAHs-degrading bacteria PAHs having low molecular weight (i.e., naphthalene, acenaphthylene, acenaphthene, and fluorene) were degraded by 9.8, 76.2, 74.1, and 40.5%, respectively. Higher molecular weight PAHs, however, maintained high residual concentrations of PAHs (400-1,000 ${\mu}g$/L) after the same treatment. On the other hand, the overall concentrations of PAHs became lower than 340 ${\mu}g$/L when the pretreated PAHs were subjected to biodegradation by a PAH-degrading consortium for a week. Herein, phenanthrene, anthracene, fluoranthene, and pyrene were removed by 29.3, 61.4, 27.0, and 44.3%, respectively, indicating the facilitated potential biodegradation of PAHs. Activated carbon coated with $TiO_2$ appeared to inhibit growth of PAH degraders on the surface of AC, indicating planktonic degraders were dominantly involved in the PAH biodegradation in presence of the $TiO_2$-coated bamboo AC. It was proposed that an effective remediation technology for the recalcitrant PAHs could be developed when an optimum pretreatment process is further established.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.2
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• pp.159-168
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• 2018

Climate change is believed to increase the amount of dissolved organic matter in surface water, as a result of the release of bulk organic matter, which make difficult to achieve a high quality of drinking water via conventional water treatment techniques. Therefore, the natural water treatment techniques, such as managed aquifer recharge (MAR), can be proposed as a alternative method to improve water quality greatly. Removal of bulk organic matter using managed aquifer recharge system is mainly achieved by biodegradation. Biodegradable dissolved organic carbon (BDOC) and assimilable organic carbon (AOC) can be used as water quality indicators for biological stability of drinking water. In this study, we compared the change of BDOC and AOC with respect to pretreatment methods (i.e., ozone or peroxone). The oxidative pretreatment can transform the recalcitrant organic matter into readily biodegradable one (i.e., BDOC and AOC). We also investigated the differences of organic matter characteristics between BDOC and AOC. We observed the decreases in dissolved organic carbon (DOC) and the tryptophan-like fluorescence intensities. Liquid chromatographic - organic carbon detection (LC-OCD) analysis also showed the reduction of the low molecular weight (LMW) fraction (15% removed, less than 500 Da), which is known to be easily biodegradable, and the biopolymers, high molecular weight fractions (66%). Therefore, BDOC consists of a broad range of organic matter characteristics with respect to molecular weight. In AOC, low molecular weight organic matter and biopolymers fraction was reduced by 11 and 6%, respectively. It confirmed that biodegradation by microorganisms as the main removal mechanism in AOC, while BDOC has biodegradation by microorganism as well as the sorption effects from the sand. $O_3$ and $O_3+H_2O_2$ were compared with respect to biological stability and dissolved organic matter characteristics. BDOC and AOC were determined to be about 1.9 times for $O_3$ and about 1.4 times for $O_3+H_2O_2$. It was confirmed that $O_3$ enhanced the biodegradability by increasing LMW dissolved organic matter.

• Journal of Environmental Science International
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• v.19 no.9
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• pp.1077-1082
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• 2010

This study was performed to investigate the nutritional conditions controlling keratinase activity in Bacillus megaterium F7-1. B. megaterium F7-1 produced keratinase using chicken feather as a sole source of carbon, nitrogen and sulfur. Addition of the feather medium with glucose enhanced keratinase production (68.9 U/ml), compared to control without glucose (63.2 U/ml). The synthesis of keratinase was repressed by addition of $NH_4Cl$ in B. megaterium F7-1. The highest keratinase production (70.9 U/ml) was obtained with the feather medium containing glucose and $MgSO_4{\cdot}7H_2O$. Keratinase was produced in the absence of feather (4.9 U/ml), indicating its constitutive synthesis. Feather degradation resulted in free SH group formation. B. megaterium F7-1 effectively degraded chicken feather meal (86%), whereas duck feather, human nail, human hair and sheep wool displayed relatively low degradation rates (8-34%).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.5
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• pp.282-287
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• 2007

Chloroanilines are aromatic amines used as intermediate products in the synthesis of herbicides, azo-dyes, and pharmaceuticals. 3,4-dichloroaniline (DCA) is the degradation product of some herbicides (diuron, propanil, and linuron) and of trichlorocarbanilide, a chemical used as an active agent in the cosmetic industry. The compound, however, is considered a potential pollutant due to its toxicity and recalcitrant property to humans and other species. With the increasing necessity for bioremediation, we sought to isolate bacteria that degraded 3,4-DCA. A bacterium capable of growth on 3,4-DCA as the sole carbon source was isolated from seaside sediment using a dilution method with a culture enriched in 3,4-DCA. The isolated strain, YM-7 was identified to be Pseudomonas sp. The isolated strain was also able to degrade other chloroaniline compounds. The isolated strain showed a high level of catechol 2,3-dioxygenase activity on exposure to 3,4-DCA, suggesting that this enzyme is an important factor in 3,4-DCA degradation. The activity toward 4-methylcatechol was 53.1% that of catechol, while the activity toward 3-methylcatechol, 4-chlorocatechol and 4,5-chlorocatechol was 18.1, 33.1, and 6.9%, respectively.

• Environmental Engineering Research
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• v.24 no.3
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• pp.513-520
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• 2019

In this investigation, nano ZnO was sonochemically synthesized by a novel method using a methionine precursor. A narrow size distribution (41-50 nm) of nano ZnO was achieved that was immobilized on perlite and applied as a catalyst in catalytic ozonation. The catalyst was characterized by fourier transform infrared spectroscopy, BET surface area, and field emission scanning electron microscope. The ozonation of recalcitrant Remazol black 5 (RB5) di-azo dye solution by means of the synthesized catalyst was investigated in a bubble column slurry reactor. The influence of pH values (7, 9, 11), catalyst dosage (8, 12, 15, $20g\;L^{-1}$) and reaction time (10, 20, 30, 60 min) was investigated. Although the dye color was completely removed by single ozonation at a higher reaction time, the applied nanocatalyst improved the dye declorination kinetics. Also, the degradation of the hazardous aromatic fraction of the dye was enhanced five-times by catalytic ozonation at a low reaction time (10 min) and a neutral pH. The second-order kinetics was best fitted in terms of both RB5 color and its aromatic fraction removal. The total organic carbon analysis indicated a significant improvement in the mineralization of RB5 by catalytic ozonation using the nano-ZnO/perlite catalyst.

• Korean Journal of Environmental Biology
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• v.18 no.3
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• pp.307-313
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• 2000

Aromatic hydrocarbons are known to be recalcitrant, so that they have been concerned as pollutant chemicals. Microorganisms play a major role in the breakdown and mineralization of these compounds. However, the kinetics of the biodegradation process may be much slower than desired from environmental consideration. The biodegradation of aromatic hydrocarbons is conducted by oxidation to produce catechol as a common intermediate which is metabolized for carbon and energy sources. In this study, a bacterial isolate capable of degrading several aromatic hydrocarbons was isolated from the contaminated wastewater of Yeocheon industrial complex. On the basis of biochemical characteristics and major cellular fatty acids, the isolate was identified as Pseudomonas putida Z104. The strain Z104 can utilize benzoate and catechol as the sole carbon and energy sources via a serial degradative pathway. The strain degraded actively 0.5 mM catechol in MM2 medium at pH 7.0 and 3$0^{\circ}C$.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.1
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• pp.47-51
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• 2000

2,4,5-trichlorophenoxyacetic acid (2,4,5-T)-degrading bacterial strains were isolated from rice field and field in suburbs of Taejon. Of the total 100 isolates, 19 strains were selected by fast growth on solid minimal media containing 2,4,5-T as a sole of carbon and energy, and they were identified to genus level. 11 strains were identified as Pseudomonas, 4 strains as Acinetobacter, 1 strains were as Alcaliagenes and 3 strains were not identified. Strains MU19 and MU92 which were identified as Pseudomonas were capable of degradation for 4 kinds of chlorinated aromatic hydrocarbons, 2,4-D, 2,4,5-T, MCPA and 3CB. Acinetobacter sp. MU38 showed the highest degradability in liquid minimal media at 48 hours after inoculation, and Pseudomonas spp. MU19. MU57, MU73, and MU92 were able to degrade carbon source at higher rates. As the results Acinetobacter sp. MU38 and Pseudomonas spp. MU19 and MU92 were capable of biodegradation for broad range of halogenated aromatic hydrocarbons, and had higher rates of degradation for 2,4,5-T.

• Analytical Science and Technology
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• v.23 no.1
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• pp.36-44
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• 2010

This study was performed to investigate the distribution and decomposition characteristics of organic matter in stream water and sewage effluent located in Gwangju. Average of dissolved organic carbon (DOC) to total organic carbon (TOC) ratio was approximately 73.9% in the Youngsan river system. The concentration of refractory dossolved carbon (RDOC) was 3.7 mg/L corresponding to 80.9% of the DOC. The ratio of recalcitrant organic carbon was relatively higher than that of biodegradable organic carbon in stream. Oxidation efficiencies in the stream were 45.0% for BOD, 63.0% for $COD_{Mn}$ and 106.5% for CODcr. In case of sewage effluent was 33.6%, 65.7% and 136.1% respectively. Mean decomposition rate ($K_d$) of Youngsan river mainstream, its tributary sites and sewage effluent were about $0.042\;day^{-1}$, $0.043\;day^{-1}$ and $0.028\;day^{-1}$, respectively and the difference was not significant between the mainstream and its tributary sites (t-test, p>0.05). $K_d$ of the sewage effluent was lower than that of stream water.