• Journal of Plant Biotechnology
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• 제35권1호
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• pp.41-45
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• 2008

Laccase (EC 1.10.3.2) is a small group of enzymes that catalyze the oxidation of a broad range of phenolic compounds including hazardous and recalcitrant pollutants in the environment. This study attempted to develop an efficient system for production of a recombinant laccase by chloroplast genetic transformation of tobacco. Chloroplast transformation vector was constructed and introduced into the tobacco chloroplast genome using particle bombardment. Chloroplast-transformed plants were subsequently regenerated. PCR and southern blot analyses confirmed stable integration of the laccase gene into the chloroplast genome. Northern blot analysis revealed that mRNA of the laccase gene was highly expressed in chloroplast-transformed plants.

• 한국수산과학회지
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• 제40권5호
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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.

• Journal of Microbiology
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• 제45권3호
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• pp.213-218
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• 2007

Trametes versicolor has a lignin degrading enzyme system, which is also involved in the degradation of diverse recalcitrant compounds. Manganese-dependent peroxidase (MnP) is one of the lignin degrading enzymes in T. versicolor. In this study, a cDNA clone of a putative MnP-coding gene was cloned and transferred into an expression vector (pBARGPE1) carrying a phosphinothricin resistance gene (bar) as a selectable marker to yield the expression vector, pBARTvMnP2. Transformants were generated through genetic transformation using pBARTvMnP2. The genomic integration of the MnP clone was confirmed by PCR with bar-specific primers. One transformant showed higher enzyme activity than the recipient strain did, and was genetically stable even after 10 consecutive transfers on non-selective medium.

• Environmental Engineering Research
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• 제23권4호
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• pp.390-396
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• 2018

This study investigated the transformation of dissolved organic matter (DOM) in a free-water surface flow constructed wetland. Pyrolysis gas chromatography-mass spectrometry (Py-GC/MS) coupled with preparative high-performance liquid chromatography (prep-HPLC) was used to analyze the compositions of biopolymers (polysaccharides, amino sugars, proteins, polyhydroxy aromatics, lipids and lignin) in DOM according to the molecular size at three sampling points of the water flow: inflow, midflow, and outflow. The prep-HPLC results verified the decomposition of DOM through the decrease in the number of peaks from three to one in the chromatograms of the sampling points. The Py-GC/MS results for the degradable peaks indicated that biopolymers relating to polysaccharides and proteins gradually biodegraded with the water flow. On the other hand, the recalcitrant organic fraction (the remaining peak) in the outflow showed a relatively high concentration of aromatic compounds. Therefore, the ecological processes in the constructed wetland caused DOM to become more aromatic and homogeneous. This indicated that the constructed wetland can be an effective buffer area for releasing biochemically stable DOM, which has less influence on biological water quality indicators, e.g., biochemical oxygen demand, into an aquatic ecosystem.

• Journal of Microbiology and Biotechnology
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• 제11권4호
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• pp.668-676
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• 2001

Pseudomonas sp. strain SY5 is a PCB-degrading bacterium [24] that includes two different enzymes (BphC1 and BphC2) encoding 2,3-dihdroxybiphenyl 1,2-dioxygenase and BphD encoding 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate hydrolase. The bphC1 and bphC2 genes were found to consist of 897 based encoding 299 amino acids and 882 bases encoding 294 amino acids, respectively, whereas the bphD gene consisted of 861 bases encoding 287 amino acids. According to a homology search, a 50% and 39% similarity between the bphC1 and bphC2 genes at the nucleotide and amino acid level was shown, respectively. The bphC1 gene showed a 38% and 45% similarity at the amino acid level to Alcaligenes eutrophus A5 and Rhodococcus rhodochrous, respectively, whereas, bphC2 showed a 95% and 43% similarity, respectively. A comparison of the deduced amino acid sequence of the bphD product of Pseudomonas sp. SY5 with that of A. eutrophus A5, Pseudomons sp. KKS102, and LB400 showed a sequence identity of 92, 92, and 79%, respectively. Strain SY5 was originally isolated from municipal sewage containing recalcitrant organic compounds an found to have a high degradability of various aromatic compounds [23]. The current study found that strain SY5 had two extradiol-type dioxygenases, which did not hybridize with each other as they had a low similarity, yet a similar structure of evolutionarily conserved amino acids residues for catalytic activity between BphC1 and BphC2 was observed.

• Advances in environmental research
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• 제9권3호
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• pp.191-214
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• 2020

The rise in population and industrialization accounts for the generation of a huge amount of wastewaters. The treatment of this wastewater is obligatory to safeguard the environment and various life forms. Conventional methods for high strength wastewater treatment coming out to be ineffective. Advanced oxidation processes (AOPs) for such wastewater treatment proved to be very effective particularly for the removal of various refractory compounds present in the wastewater. Ozone based AOPs with its high oxidizing power and excellent disinfectant properties is considered to be an attractive choice for the elimination of a large spectrum of refractory compounds. Furthermore, it enhances the biodegradability of wastewaters after treatment which favors subsequent biological treatments. In this review, a detailed overview of the AOPs (like the Fenton process, photocatalysis, Electrochemical oxidation, wet air oxidation, and Supercritical water oxidation process) has been discussed explicitly focusing on ozone-based AOPs (like O₃, O₃/H₂O₂, O₃/UV, Ozone/Activated carbon process, Ozone/Ultrasound process, O₃/UV/H₂O₂ process). This review also comprises the involved mechanisms and applications of various ozone-based AOPs for effective municipal/industrial wastewaters and landfill leachate treatment. Process limitations and rough economical analysis were also introduced. The conclusive remarks with future research directions also underlined. It was found that ozonation in combination with other effective AOPs and biological methods enhances treatment efficacies. This review will serve as a reference document for the researchers working in the AOPs field particularly focusing on ozone-based AOPs for wastewater treatment and management systems.

• 미생물학회지
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• 제46권1호
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• pp.93-95
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• 2010

리그닌 분해효소 군을 가진 백색부후균들은 다핵방향족 화합물을 포함하여 염료와 폭약 및 내분비장애 물질의 분해 등 다양한 난분해성 물질을 분해할 수 있다. 리그닌 분해효소 중 laccase와 manganese peroxidase (MnP)를 각각 발현하는 벡터를 국내에서 분리한 백색부후균류의 하나인 아교버섯(Phlebia tremellosa)에 형질전환 방법으로 도입시킨 형질전환체를 사용하여 염료의 탈색능력을 분석하였다. Methyl green의 경우 3일 후 약 50%의 탈색을 보인 야생형에 비하여 laccase 형질전환체(TF2-1)와 MnP 형질전환체(T5) 모두 90% 이상의 탈색을 보였다. Remazol brilliant blue R (RBBR)에서는 야생형이 약 67%의 탈색을 보인 반면 두 가지 형질전환체들은 약 85%의 탈색을 보였다. 각각의 형질전환체들은 laccase와 MnP의 활성 및 유전자 발현도 활발한 것으로 확인되었다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제7권3호
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• pp.61-70
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• 2002

난분해성 유기오염물로 오염된 토양 복원을 위한 전자빔 직접조사 공정의 적용가능성을 평가하기 위하여 PAHs 와 PCBs로 오염시킨 토양에 대한 전자빔 조사실험을 수행하였다 전자빔 흡수선량 600kGy에서 PAHs의 제거율은 약 97% 이었고 PCBs는 800kGy에서 약 70%가 제거되었다. PAHs는 PCBs에 비해 낮은 흡수선량에서도 높은 제거율을 나타내었다. 오염물의 분해는 가속된 전자와 물의 반응으로 생성된 반응성 높은 중간생성물에 의한 산화/환원 반응보다는 고에너지 전자와 대상오염물의 직접적인 반응에 기인한다. 전자빔 조사에 의해 난분해성 오염물질로 오염된 토양을 효과적으로 제거할 수 있으나 이를 위해 높은 에너지를 요구하므로 비경제적인 공법이 될 수 있다. 따라서, 전자빔 직접조사 공정보다는 기존 토양복원 공법의 후처리 공정으로 개발하는 것이 경제적이고 실용화 가능할 것으로 판단된다.

• 상하수도학회지
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• 제33권1호
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• pp.31-41
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• 2019

Volatile organic compounds(VOCs) are toxic carcinogenic compounds found in wastewater. VOCs require rapid removal because they are easily volatilized during wastewater treatment. Electrochemical advanced oxidation processes(EAOPs) are considered efficient for VOC removal, based on their fast and versatile anodic electrochemical oxidation of pollutants. Many studies have reported the efficiency of removal of various types of pollutants using different anodes, but few studies have examined volatilization of VOCs during EAOPs. This study examined the removal efficiency for VOCs (chloroform, benzene, trichloroethylene and toluene) by oxidization and volatilization under a static stirred, aerated condition and an EAOP to compare the volatility of each compound. The removal efficiency of the optimum anode was determined by comparing the smallest volatilization ratio and the largest oxidization ratio for four different dimensionally stable anodes(DSA): Pt/Ti, $IrO_2/Ti$, $IrO_2/Ti$, and $IrO_2-Ru-Pd/Ti$. EAOP was operated under same current density ($25mA/cm^2$) and electrolyte concentration (0.05 M, as NaCl). The high volatility of the VOCs resulted in removal of more than 90% within 30 min under aerated conditions. For EAOP, the $IrO_2-Ru/Ti$ anode exhibited the highest VOC removal efficiency, at over 98% in 1 h, and the lowest VOC volatilization (less than 5%). Chloroform was the most recalcitrant VOC due to its high volatility and chemical stability, but it was oxidized 99.2% by $IrO_2-Ru/Ti$, 90.2% by $IrO_2-Ru-Pd/Ti$, 78% by $IrO_2/Ti$, and 75.4% by Pt/Ti anodes The oxidation and volatilization ratios of the VOCs indicate that the $IrO_2-Ru/Ti$ anode has superior electrochemical properties for VOC treatment due to its rapid oxidation process and its prevention of bubbling and volatilization of VOCs.

• 미생물학회지
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• 제30권3호
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• pp.207-212
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• 1992

합성세제 분해능이 월등한 Pseudomonas putida 와 프탈산에스테르를 분해하는 Arthobacter spp. 의 세포융합을 통해 합성세제와 프탈산에스테르의 분해능을 모두 갖는 융합균주를 개발하였다. Ampicillin-Lysozyme-EDTA 에 의한 각 균주의 원형진체 생성율은 98.4%-99.9% 이었고 원형질체의 재생율은 5-8%이었다. Fusogen으로 40%PEG4000 을 이용하였을 때 효과적으로 융합이 이루어졌으며 융합율은 $1.8{\times}10^{4} $-2.9{\times}10^{4}$ 이었다. 선별된 융합체는 프탈산에스테르와 ABS 를 모두 분해하였으며 ABS 의 분해능은 모균주보다 약 20% 정도 분해능이 증가하였고 DEHP 의 분해능은 모균주와 비슷한수준이었으나 모균주보다 더 빨리 기질을 분해하였다.