• Journal of Life Science
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• v.30 no.10
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• pp.919-929
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• 2020

Aromatic compounds are widely used in the chemical, food, polymer, cosmetic, and pharmaceutical industries and are produced by mainly chemical synthesis using benzene, toluene, and xylene or by plant extraction methods. Due to many rising threats, including the depletion of fossil fuels, global warming, the strengthening of international environmental regulations, and the excessive harvesting of plant resources, the microbial production of aromatic compounds using renewable biomass is regarded as a promising alternative. By integrating metabolic engineering with synthetic and systems biology, artificial biosynthetic pathways have been reconstituted from L-tryptophan biosynthetic pathway in relevant microorganisms, such as Escherichia coli and Corynebacterium glutamicum, enabling the production of a variety of value-added aromatic compounds, such as 5-hydroxytryptophan, serotonin, melatonin, 7-chloro-L-tryptophan, 7-bromo-L-tryptophan, indigo, indirubin, indole-3-acetic acid, violacein, and dexoyviolacein. In this review, we summarize the characteristics, usage, and biosynthetic pathways of these aromatic compounds and highlight the latest metabolic engineering strategies for the microbial production of aromatic compounds and suitable solution strategies to overcome problems in increasing production titers. It is expected that strain development based on systems metabolic engineering and the optimization of media and bioprocesses using renewable biomass will enable the development of commercially viable technologies for the microbial production of many aromatic compounds.

• Korean Journal of Food Science and Technology
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• v.25 no.4
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• pp.379-385
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• 1993

Antioxidative effectiveness and oxidized products in mixture of methyl linoleate(ML) and phenolic compounds were investigated under oxygen blowing at $37^{\circ}C$ for 9 days. Caffeic acid (3,4-dihydroxy cinnamate ; CML) and phloroglucinol(1,3,5-trihydroxy benzene ; PML) showed higher antioxidative effectiveness for methyl linoleate than 0.05% ${\alpha}-tocopherol$ (TML). Oxidized products in ML group were methyl 8-(2-furyl)-octanoate, 9,13-trans, cis hydroperoxide isomer, 9,13-trans, trans hydroperoxide isomer, and 9-TMSO-12,13-epoxy-10-octadecenoate. In CML group the oxidized products were methyl-8-(2-furyl)-octanoate, 9-trans, cis hydroperoxide isomer and 9-trans, trans hydroperoxide isomer, but 13-hydroxy isomer was not identified. It was shown that CML were oxidized more slowly than ML group and at 6th day of oxidation, caffeic quinone was found to be major oxidized product of caffeic acid. Oxidixed Products in PML group were methyl-8-(2-furyl)-octanoate, 9-trans, cis hydroperoxide isomer, and 9-trans, trans hydroperoxide isomer but phloroglucinol was not oxidized even at the 9th day of reaction.

• Journal of the Korean Chemical Society
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• v.41 no.7
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• pp.337-342
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• 1997

Acryloylmethylbenzo-15-crown-5 was prepared from the reaction of 4'-hydroxymethylbenzo-15-crown-5 with acryloyl chloride. And, poly(acryloylmethylbenzo-15-crown-5) [poly(AMB15C5)] was synthesized by radical polymerization using AIBN as initiator in benzene. Coated wire lead(II) ion-selective electrodes ($Pb^{2+}$-CWISEs) using either poly(AMB15C5) or B15C5 as neutral carrier were prepared, respectively. $Pb^{2+}$-CWISEs gave linear responses with slopes of 28$\pm$ 1mV per decade within the concentration range of $10^{-5} M{\sim}10^{-1}$ M, respectively. Also, the detection limits were $10^{-6}$ M and response times were either 3 or 5 min. for B15C5 and poly(AMB15C5), respectively. $Pb^{2+}$-CWISE base on B15C5 was rather unstable than poly(AMB15C5)'s due to solubility of the B15C5 in water. The selectivity coefficients of a variety of interfering ions such as $Mg^{2+},\; Ca^{2+},\; Co^{2+},\; Ni^{2+},\; Cu^{2+},\; Zn^{2+}$ and $Cd^{2+}$ were small ($10^{-4}{\sim}10^{-5}$), while those of $Na^+$ and $K^+$ were large (0.1∼0.01). In addition, the electrode responses depended upon the pH of test solution and the composition of the membrane. In the range pH 3∼6 of test solution, potentials of Pb2+-CWISEs were hardly changed. The optimal contents of B15C5 and poly(AMB15C5) were 7.7 wt% and 13.1 wt%, respectively.

• Clean Technology
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• v.23 no.4
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• pp.364-377
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• 2017

In this study, to improve the low surface area of domestic anthracite as raw materials of activated carbon, characteristics on chemical activation and VOCs adsorption of activated carbon according to mixing ratio of anthracite and lignite. For these, properties of raw materials, parameter characteristics of preparation processes for activated carbon, and VOCs adsorption characteristic of the prepared activated carbon are analyzed. The experimental results showed that, the domestic anthracite had disadvantages of high contents for ash and lead, arsenic, which were exceeded for the heavy metal limits, in the properties of raw materials. To improve these diadvantages, using the mixing ratio of anthracite and lignite, and the optimum conditions for pretreatment, activation, washing, and pellitization process, the activated carbon had a range of BET (Brunauer-Emmett-Teller) surface area of $1,154{\sim}1,420m^2g^{-1}$ with mesopore development and hydrophobic surface property. The carbons were satisfied with the quality standard for granular activated carbon, and had similar physicochemical properties with the commercial activated carbon. The minimum mixing condition for commercial VOCs activated carbon performance must have the caloric value of above $5,640kcal\;kg^{-1}$, and the carbon had higher adsorption capacity with order of xylene > toluene > benzene according to more higher molcular weight and hydrophobic property.

• Korean journal of applied entomology
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• v.51 no.3
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• pp.245-253
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• 2012

Benzylinedeneacetone (BZA) is a bacterial metabolite which is synthesized by at least two entomopathogenic bacteria, namely Xenorhabdus nematophila and Photorhabdus temperata subsp. temperata. It has been shown to possess inhibitory effects on insect cellular and humoral immune responses as well as antimicrobial activities against various species of bacteria and fungi. However, its relatively high phytotoxicity, and nonsystematic effect have thus far prevented its development into an optimal pesticide. This study screened five different BZA derivatives in order to select an optimal compound, which would have relatively high solubility and low phytotoxicity while retaining sufficient degrees of the immunosuppressive and antimicrobial activities associated with BZA. Hydroxylation of the benzene ring of BZA was found to significantly suppress its immunosuppressive and antimicrobial activities. Transformation of the ketone of BZA by carboxylation also suppressed the inhibitory activities. However, a shortening of the aliphatic chain of BZA into acetate form (4-hydroxyphenylacetic acid: HPA) did not decrease the inhibitory activity. HPA also showed much less phytotoxicity against the hot pepper plant Capsicum annuum, when compared to BZA. This study identified an optimal BZA derivative, which exhibited relatively little phytotoxicity, but retained a high degree of inhibitory activity to suppress insect immune responses and antimicrobial activities against plant pathogens.

• YAKHAK HOEJI
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• v.36 no.1
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• pp.1-6
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• 1992

Irradiation of phenolbetaine in a stream of nitrogen produced 8,14-cycioberbine[1]. Compound[1] was treated with 10% HCl solution to give the 8-hydroxycycloberbine[2] in 67.7% yield. Subsequently addition of ethylchloroformate to the compound[2] gave rise to the 8-hydroxy-7-ethylcarboxy-9, 10-dimethoxy-2, 3-methylenelioxy-13-oxo-norochotensane[3] in 78% yield. Treatment of the compound[3] with bis-(2-chloroethyl)amine then lead to the 7-bis(2-chloroethyl)carbamyl-norochoteneare[4]. On the other hand the compound[5], which is the 8-methoxynorochotensane, was derived when compound[1] was treated with methanol in a few drops of BF. Treatment of the compound[6], and the compound[7], 7-bis(2-chloroethyl)-carbanyl-8-methoxy-norocheyensane, was then synthesized by reaction of the compound[6] with bis(2-chloroethyl) amine. In the other synthetic pathway when compound[5] was treated with $POCl_3$ in dried benzene, 13-chloro-6-ene-norochetensane[8] with 42% yield was formed. Finally the 13-bis-(2-chloroethyl) amino-8-methoxy-norochotensane[9] was produced when we treated the compound[8] with bis-(2-chloroethyl) amine. In another pathway, reaction between phenolbetaine which is the precursor of the compound[1] and benzoylchloride in dried chloroform gave us the 5,6,7 trihydro-2, 3-methylene-dioxy-9-chloromethyl-10, 11-dimethoxyphenylisoquinoline-8-benzoate[10] in 73% yield. The results of biological activities for these compounds are also presented in Table I and II.

• Journal of the Korean Wood Science and Technology
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• v.33 no.4 s.132
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• pp.30-37
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• 2005

Heating and Steaming treatments were carried for deresinning and color change of radiata pine juvenile wood. The boards of 20 mm and 30 mm thicknesses were heat-treated at $150^{\circ}C$ and $220^{\circ}C$ for 2, 4 and 6 hours and steamed at $100^{\circ}C$ for 6, 24 and 48 hours. For extracting residual resin in treated boards and measuring wood surface color, alcohol-benzene solution and a portable colorimeter were used, respectively. The board of 20 mm thickness were deresined effectively by heating at over $150^{\circ}C$ for 2 hours or steaming for 6 hours while that of 30 mm thickness by steaming for 48 hours. For the board of 30 mm thickness treatment time was more influencing on deresinning than treatment temperature. The steamed boards showed higher $L^*$ than the heat-treated for both thicknesses. $L^*$ decreased with the increase of treatment temperature and time, but for the board heat-treated at $220^{\circ}C$ it didn't change after 4 hours. The surface color of the boards heat-treated at $220^{\circ}C$ for 4 and 6 hours were obviously changed, but those at $150^{\circ}C$ were not. It was revealed that the core of the heat-treated board was color changed as well as the surface.

• Journal of Environmental Policy
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• v.4 no.2
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• pp.57-82
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• 2005

In this study, we propose methods for. the efficient management and integrity of groundwater in response to a diminishing supply. As an alternative water resource for the future. we investigated and comparatively analyzed the quality standards of groundwater in the US (New York, Wisconsin and Texas), Austria, Netherlands, Canada, Japan and United Kingdom. These developed countries heavily depend on groundwater, more than 70%, for drinking water and apply those drinking water standards to groundwater quality. However, there exists few differences in the quality standards of groundwater among the countries, because each country possesses its own individual environment and management. In Korea, surface water pollution is getting serious and its water resources are diminishing. Therefore we propose several new quality criteria that many countries regulate at these days for their efficient management of groundwater. There is a need to divide BTEX criterion into Benzene, Toluene, Ethylbenzene and Xylene, individually. In. addition, it is needed to establish BTEX criteria into agricultural water and industrial water use standards as well as daily life use standards. Also, regulations for some PAHs, showing carcinogenicity, are required. Due to rapid industrialization various hazardous chemicals were utilized and their uses are increasing each year. Therefore, there is a strong need to introduce n~w standards and tighter regulations of the levels. At the same time, the criterion of nitrogenous compounds need' to be regulated individually in order to prevent the damage incurred by the compounds. Several developed countries have established standards for radon, previously caused environmental accidents in Korea. Therefore, we propose the necessity of groundwater quality standards for radon in this study.

• Journal of Environmental Health Sciences
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• v.32 no.5 s.92
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• pp.404-411
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• 2006

이 연구의 목적은 유치원에서 총 휘발성 유기화합물의 농도를 평가하고, 총 휘발성 유기화합물 농도와 대표적인 8개 방향족 화합물의 상관관계를 조사하는데 있다. 도시에 위치한 11개 유치원의 실내와 실외에서 각각 30개, 11개의 지역시료를, 시골에 위치한 4개 유치원에서는 각각 10개, 4개의 시료를 테낙스 튜브를 이용하여 오전에 1-2시간 채취하였다. 채취한 시료는 열탈착하여 가스크로마토그래피-질량분석기로 분석하였다. 13가지 물질을 각각의 표준물질로 개별 정량하여 이중 빈번히 발견되는 8가지 방향족 유기화합물은 상관관계 평가에 사용하였다. 총 휘발성 유기화합물은 톨루엔을 기준으로 정량하였다. 도시에 위치한 유치원 실내의 총 휘발성 유기화합물 농도가 높았고, 조사 건수의 50%가 환경부 및 교육인적자원부의 가이드라인($400{\mu}g/m^{3}$)을 초과하였다. 도시지역의 유치원 실내 및 실외의 기하평균은 각각 $387.9{\mu}g/m^{3}$과 $134.9{\mu}g/m^{3}$이었고, 시골지역 유치원에서는 각각 $189.6{\mu}g/m^{3},;74.4{\mu}g/m^{3}$이었다. 톨루엔, 크실렌, 에틸벤젠, 정량한 유기 화합물 총합, 총 휘발성 유기화합물은 기하정규분포를 하였다. 벤젠, 톨루엔, 에틸벤젠, 크실렌(BTEX)은 도시에 위치한 유치원에서 농도도 높고, 총 휘발성 유기화합물중 함량도 높았고, 시골지역에서는 농도와 상대적 함량이 낮았다. 도시지역에서는 총 휘발성 유기화합물 중 BTEX의 비중이 25.2%였고 정량한 13가지 유기화합물 중에서는 35.6%를 차지하였다. BTEX 각각 개별물질은 미국 환경보호청이 제시하는 일일 노출 기준량(Reference Concentration; RfC) 보다는 현저히 낮았다. 총 휘발성 유기화합물읜 농도는 실내가 실외 보다 높았다(I/O ratio 2.5). BTEX의 상대적 함량도 실내가 실외보다 높아 실내에도 발생원이 있음을 암시하고 있다. 자료 분석결과 유치원 실내의 벤젠은 실외로부터 유입되고 있었고, 톨루엔, 에틸벤젠, 크실렌은 실외뿐 아니라 실내에서도 발생하고 있었다. 정량한 8개 화합물 각각과 총 휘발성 유기화합물의 스피어만 상관계수는 벤젠을 제외하고는 모두 유의하였다. 이중 톨루엔과 크실렌은 총 휘발성 유기화합물과 좋은 상관성 (톨루엔 0.76, 크실렌, 0.87)을 나타내었다. 이 연구는 톨루엔과 크실렌이 총 휘발성 유기화합물의 좋은 지표를 사용될 있고, 톨루엔, 에틸벤젠, 크실렌 등 많은 휘발성 유기화합물의 발생원은 실외뿐 아니라 실내에도 있음을 나타내고 있다.

• Journal of the Korean Chemical Society
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• v.27 no.3
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• pp.201-207
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• 1983

The rate constants for solvated electrons with benzene in the binary mixture (tetrahydrofuran-water) were measured at a various temperatures$(-18{\circ}C{\sim}+51{\circ}C)$ by photolysis. From Arrhenius plots of rate constants it was observed that the activation energies were decreased with increasing tetrahydrofuran(THF) content. Decreasing the viscosity of solvent mixtures by adding water, the rate constants were also decreased. It indicates that the reaction of solvated electrons are not controlled by diffusion. The change of activation enthalpy in kcal $M^{-1}$ and the rate constants in$ M^{-1}sec^{-1}$ were 4.90 and $8.80{\times}10^8$ for 30M% of THF, 2.80 and $5.14{\times}10^8$ for 49M% of THF, and -0.30 and %1.43{\times}10^8$ for 75M% of THF, respectively. The slope of the linear plot of activation enthalpies against activation entropies was $244{\circ}K$, which supports the reaction parameter is the change of activation entropy in the range of the experimental temperature. From the solvent effect on the activation energy, it was found that the step of the reaction, ${e_s}^-+B{\rightleftharpoons}B^-$ shifted to the exothermic reaction with increasing THF content.