• 한국지하수토양환경학회지:지하수토양환경
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• 제24권6호
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• pp.16-25
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• 2019

Anthropogenic polycyclic aromatic hydrocarbons (PAHs) are formed by the incomplete combustion of fuels and industrial waste. PAHs can be widely exposed to the environment (water, soil and groundwater). PAHs are potentially toxic, mutagenic and/or carcinogenic. Fundamental studies such as biota uptake (e.g., earthworm and plant) of PAHs are highly needed. It is necessary to develop alternative ways to evaluate bioavailability of PAHs instead of using living organisms because it is time-consuming, difficult to apply in the field, and also exaction method is tedious and time-consuming. In this study, sorption behaviors of phenanthrene were evaluated to predict the fate of PAHs in soils. Moreover, bioaccumulation of PAHs in an artificially contaminated soil was evaluated using pea plant (Pisum sativum) as a bioindicator. A novel passive sampler, organic-diffusive gradient in thin-film (o-DGT) for PAHs was newly synthesized, tested as a biomimic surrogate and compared with plant accumulation. Sorption partitioning coefficient (K_P) and sorption capacity (K_F) were in the order of natural soil > loess corresponding to the increase in organic carbon content (f_oc). Biota-to-soil accumulation factor (BSAF) and DGT-to-soil accumulation factor (DSAF) were evaluated. o-DGT uptake was linearly correlated with pea plant uptake of phenanthrene in contaminated soil (R²=0.863). The Tenax TA based o-DGT as a biomimic surrogate can be used for the prediction of pea plant uptake of phenanthrene in contaminated soil.

• 한국대기환경학회지
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• 제34권3호
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• pp.418-429
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• 2018

Measurements of 24-hr size-segregated ambient particles were made at an urban site of Gwangju under high pressure conditions occurred in the Korean Peninsula late in March 2018. The aim of this study was to understand the effect of air stagnation on mass size distributions and formation pathways of water-soluble organic and inorganic components. During the study period, the $NO_3{^-}$, $SO_4{^{2-}}$, $NH_4{^+}$, water-soluble organic carbon (WSOC), and humic-like substances(HULIS) exhibited mostly bi-modal size distributions peaking at 1.0 and $6.2{\mu}m$, with predominant droplet modes. In particular, outstanding droplet mode size distributions were observed on March 25 when a severe haze occurred due to stable air conditions and long range transport of aerosol particles from northeastern regions of China. Air stagnation conditions and high relative humidity during the study period resulted in accumulation of primary aerosol particles from local emission sources and enhanced formation of secondary ionic and organic aerosols through aqueous-phase oxidations of $SO_2$, $NO_2$, $NH_3$, and volatile organic compounds, leading to their dominant droplet mode size distributions at particle size of $1.0{\mu}m$. From the size distribution of $K^+$ in accumulation mode, it can be inferred that in addition to the secondary organic aerosol formations, accumulation mode WSOC and HULIS could be partly attributed to biomass burning emissions.

• 한국미생물·생명공학회지
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• 제18권3호
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• pp.273-279
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• 1990

PHB 생산을 위하여 메탄올을 기질로 한 선별배지에서 토양, 하천수, 퇴비 등으로부터 분홍색 색소를 가지는 PHB 축적 facultative methylotroph를 분리하여, 균주의 특성을 검토하였다. 분리균주의 최적 생육조건과 PHB 축적을 위한 배양조건을 조사한 결과 균체의 생육은 메탄올 농도 1.0(v/v), 질소원인$ NH_4C$ 농도 1.0g/l, 즉 C/N ratio 13.2 일때 그리고 pH 7.0과'$30^{\circ}C$에서 가장 좋았으며, PHB는 C/N ratio가 50.8, 즉 메탄올 농도 1.0(v/v )$NH_4CL$ 0.26g/l 일때, 그리고 pH 6.0일 때 건조중량의 약 40까지 축적되었다. 고농도 메탄올에 의한 생육저해를 극복하기 위하여 기질을 간헐적으로 계속 공급해주는 fed-batch 배양을 시도한 결과 균체량은 14g/l, PHB 축척량은 5.5g/l까지 증가시킬 수 있었다. 생산된 PHB를 분리.정제하여 IR과 $^I H-NMR$로 구조를 분석한 결과 3-hydroxybutyric acid 의 homopolymer임이 확인되었다. 또한 균주의 pink-pigment를 추출하여 absorption spectrum를 조사하여 그 특성을 규명하였다.

• KSBB Journal
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• 제9권5호
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• pp.475-482
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• 1994

A. eutrophus 균주를 이용하여 여러 변수에 대한 균성장속도 및 PHB 축적 변화를 고찰하였다. 글루 코오스 및 $>(NH_4)_2HP0_4$를 탄소원 및 질소원으로 사용할 경우가 균 성장 및 PHB 합성에 있어서 다른 기섣에 비해 효율적이었다. $>NH_4^{3-}, P0_4^{3-}, Mg^{2+}$등 을 제한하였을 경우 PHB의 축적이 촉진되었으며, 그 중 $>NH_4^+$가 가장 효율적인 제한 인자였다. Yeast extract를 기절 중에 첨가하였을 경우 성장속도가 1.5배 정도 증가하였는 바, 이는 단백질을 비롯한 비타민과 아미노산 등의 미량원소의 영향으로 사료된다. 균 성장시 산소가 부족할 경우 배출되는 부생성 물은 주로 butanedio\과 에탄올이었으며, 그 중 에 탄올이 균 성장에 저해 효과를 나타냄을 확인하였다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제29권1호
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• pp.28-38
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• 2024

Phytoremediation presents a low-carbon and eco-friendly solution for heavy metal-contaminated soils, which pose great health and environmental risks to humans and ecosystems. A hydroponic culture was used to quantitatively assess the phytoremediation potential of plant species to remediate As or Cd-contaminated soil in field application. This study examined the growth, uptake, and distribution of Cd in the roots and shoots of Phalaris arundinacea and Brassica juncea in hydroponic conditions with Cd concentrations ranging from 0 to 20 mg/L for 10 days. Additionally, Aster koraiensis and Pteris multifida were cultivated in hydroponic conditions containing As concentrations ranging from 0 to 40 mg/L for 10 days. The concentrations of Cd in the above-ground part and root tissues of P. arundinacea and B. juncea reached a maximum of 147.7 and 1926.7 mg/kg-D.W.(Dry Weight), and 351.6 and 11305.5 mg/kg-D.W., respectively. Bioconcentration factor (BCF) for P. arundinacea and B. juncea were 68.9 and 122.3, respectively. Both species exhibited a translocation factor (TF) of less than 0.1, indicating their eligibility for phytostabilization. Aster koraiensis exhibited significant As accumulation of 155.1 and 1306.7 mg/kg D.W. in the above-ground part and root, respectively. However, this accumulation resulted with substantial weight loss and the manifestation of toxic symptoms. P. multifida exhibited higher accumulation of As (345.1 mg/kg-D.W.) in the fronds than in the roots (255.4 mg/kg-D.W.), corresponding to BCF values of 18.6 and 7.6, respectively, and a TF greater than 1.2. A TF value greater than 1.0 indicates that P. multifida is a viable option for phytoextraction.

• 환경생물
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• 제35권4호
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• pp.715-725
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• 2017

토양 유기탄소 축적량 변화와 작물의 생태계 탄소 수지를 파악하기 위하여 농업의 탄소 관리에 필요한 기초 자료 마련을 위하여 2014~2016년 (3년) 벼 재배기간 동안 토양의 유기탄소 축적량과 작물의 생태계 순 생산량을 측정하였다. 그 결과로 벼 재배지 토양 유기탄소 축적량은 NPK+볏짚퇴비 처리($3.88Mg\;C\;ha^{-1}$)에서 가장 많았고 NPK (화학비료) 처리보다 40.8%, NPK+헤어리베치 처리보다 17.0%의 축적 효과가 있었다. 그러나 NPK+볏짚퇴비 처리가 NPK+헤어리베치에 비해 토양 유기탄소 축적량이 높게 나타나 헤어리베치 시용에 비해 볏짚퇴비 시용이 농경지 내 탄소 축적량이 높은 것으로 나타났다. 벼 재배지 생태계 순 생산량은 NPK 처리($11.31Mg\;C\;ha^{-1}$)에 비해 NPK+헤어리베치 처리($14.01Mg\;C\;ha^{-1}$)에서 19.3%와 NPK+볏짚퇴비 처리($12.6Mg\;C\;ha^{-1}$)에서 10.2% 축적 효과가 있었다. 따라서 화학비료 단일 처리보다 화학비료를 절감하기 위한 유기물 처리가 토양유기탄소 축적 및 재배지의 작물 생태계 탄소 축적량을 증대시키는 효과가 있는 것으로 나타났다.

• 한국토양비료학회지
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• 제49권1호
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• pp.1-6
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• 2016

Carbonized biomass could be used as a mechanism for long-term storage of C in soils. However, experimental results are variable. Objective of this study was carried out to evaluate the effect of carbonized biomass made from soybean residue on soil organic carbon and seed yield during soybean cultivation. The carbonized biomass was made by field scale mobile pyrolyzer. Pyrolyzer was performed in a reactor operated at $400{\sim}500^{\circ}C$ for 2 hours using soybean residue. The treatments consisted of four levels as the control without input and three levels of carbonized biomass inputs as $357kg\;ha^{-1}$, C-1 ; $714kg\;ha^{-1}$, C-2 ; $1,428kg\;ha^{-1}$, C-3. It was appeared that seed yield of soybean was $2,847kg\;ha^{-1}$ for control, $2,897kg\;ha^{-1}$ for C-1, $2,946kg\;ha^{-1}$ for C-2 and $3,211kg\;ha^{-1}$ for C-3 at the end of experiment. It was shown that the contents of SOC were $5.21g\;kg^{-1}$ for C-1, $5.93g\;kg^{-1}$ for C-2, $7.00g\;kg^{-1}$ for C-3 and $4.73g\;kg^{-1}$ for the control at the end of experiment. Accumulated SOC contents linearly significantly (P < 0.001) increased with increasing the carbonized biomass input. The slopes (0.00162) of the regression equations suggest that SOC contents from the soil increase by $0.162g\;kg^{-1}$ with every $100kg\;ha^{-1}$ increase of carbonized biomass rate. Consequently the carbonized biomass for byproducts such as soybean residue could increase SOC. It might be considered that the experimental results will be applied to soil carbon sequestration for future study. More long-term studies are needed to prove how long does SOC stay in agricultural soils.

• 한국미생물·생명공학회지
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• 제46권1호
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• pp.29-39
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• 2018

Vibrio vulnificus needs various responsive mechanisms to survive and transmit successfully in alternative niches of human and marine environments, and to ensure the acquisition of steady energy supply to facilitate such unique life style. The bacterium had genetic constitution very different from that of Escherichia coli regarding metabolism of glycogen, a major energy reserve. V. vulnificus accumulated more glycogen than other bacteria and at various levels according to culture medium and carbon source supplied in excess. Glycogen was accumulated to the highest level in Luria-Bertani (3.08 mg/mg protein) and heart infusion (4.30 mg/mg protein) complex media supplemented with 1% (w/v) maltodextrin at 3 h into the stationary phase. Regarding effect of carbon source, more glycogen was accumulated when maltodextrin (2.34 mg/mg protein) was added than when glucose or maltose (0.78.1-14 mg/mg protein) was added as an excessive carbon source to M9 minimal medium, suggesting that maltodextrin metabolism might affect glycogen metabolism very closely. These results were supported by the analysis using the malP (encoding a maltodextrin phosphorylase) and malQ (encoding a 4-${\alpha}$-glucanotransferase) mutants, which accumulated much less glycogen than wild type when either glucose or maltodextrin was supplied as an excessive carbon source, but at different levels (3.1-80.3% of wild type glycogen). Therefore, multiple pathways for glycogen metabolism were likely to function in V. vulnificus and that responding to maltodextrin might be more efficient in synthesizing glycogen. All of the glycogen samples from 3 V. vulnificus strains under various conditions showed a narrow side chain length distribution with short chains (G4-G6) as major ones. Not only the comparatively large accumulation volume but also the structure of glycogen in V. vulnificus, compared to other bacteria, may explain durability of the bacterium in external environment.

• Journal of Microbiology and Biotechnology
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• 제30권6호
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• pp.868-877
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• 2020

Bicarbonate has been considered as a better approach for supplying CO₂ to microalgae cells microenvironments than gas bubbling owing to cost-effectiveness and easy operation. However, the β-carotene production was too low in Dunaliella salina cultivated with bicarbonate in previous studies. Also, the difference in photosynthetic efficiency between these two carbon sources (bicarbonate and CO₂) has seldom been discussed. In this study, the culture conditions, including NaHCO₃, Ca²⁺, Mg²⁺ and microelement concentrations, were optimized when bicarbonate was used as carbon source. Under optimized condition, a maximum biomass concentration of 0.71 g/l and corresponding β-carotene content of 4.76% were obtained, with β-carotene yield of 32.0 mg/l, much higher than previous studies with NaHCO₃. Finally, these optimized conditions with bicarbonate were compared with CO₂ bubbling by online monitoring. There was a notable difference in F_v/F_m value between cultivations with bicarbonate and CO₂, but there was no difference in the F_v/F_m periodic changing patterns. This indicates that the high concentration of NaHCO₃ used in this study served as a stress factor for β-carotene accumulation, although high productivity of biomass was still obtained.

• Journal of Microbiology and Biotechnology
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• 제9권6호
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• pp.847-853
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• 1999

A Pseudomonas sp. strain that is capable of utilizing dicarboxylic acids as a sole carbon source was isolated from activated sludge by using the enrichment culture technique. This organism accumulated polyhydroxyalkanoates (PHAs) with an unusual pattern of monomer units that depends on the carbon sources used. Polyhydroxybutyrate (PHB) homopolyester was synthesized from glucose or small $C_{-even}$ alkanoic acids, such as butyric acid and hexanoic acid. Accumulation of PHB homopolyester was also observed in the cells grown on $C_{-odd}$ dicarboxylic acids, such as heptanedioic acid and nonanedioic acid as the sole carbon sources. In contrast, a copolyester consisting of 6 mol% 3-hydroxybutyrate (3HB) and 94 mol% 3-hydroxyvalerate (3HV) was produced with a PHA content of as much as 36% of the cellular dry matter. This strain produced PHAs consisting both of the short-chain-length (SCL) and the medium-chain-length (MCL) 3-hydroxyacid units when heptanoic acid to undecanoic acid were fed as the sole carbon sources. Most interestingly, polyester consisting of significant amount of relevant fractions, 3HB, 3HV, and 3-hydroxyheptanoate (3HHp), was accumulated from heptanoic acid. According to solvent fractionation experiments, the polymer produced from heptanoic acid was a blend of poly(3HHp) and of a copolyester of 3HB, 3HV, and 3HHp units. The hexane soluble fractions contained only 3HHp units while the hexane-insoluble fractions contained 3HB and 3HV units with a small amount of 3HHp unit. The copolyester was an elastomer with unusual mechanical properties. The maximum elongation ratio of the copolyester was 460% with an ultimate strength of 10 MPa, which was very different from those of poly(3HB-co-3HV) copolyesters having similar compositions produced from other microorganisms.