• Molecular & Cellular Toxicology
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• 제1권3호
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• pp.189-195
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• 2005

Industrial development has increase consumption of crude oil and environmental pollution. A large number of microbial lipolytic enzymes have been identified and characterized to date. To development for a new lipase with catalytic activity in degradation of crude oil as a microbial enzyme, Acinetobactor sp. B2 was isolated from soil samples that were contaminated with oil in Daejon area. Acinetobactor sp. B2 showed high resistance up to 10 mg/mL unit to heavy metals such as Ba, Li, Al, Cr, Pb and Mn. Optimal growth condition of Acinetobactor sp. B2 was confirmed $30^{\circ}C$. Lipase was purified from the supernatant by Acinetobactor sp. B2. Its molecular mass was determined to the 60 kDa and the optimal activity was shown at $40^{\circ}C$ and pH 10. The activation energies for the hydrolysis of p-nitrophenyl palmitate were determined to be 2.7 kcal/mol in the temperature range 4 to $37^{\circ}C$. The enzyme was unstable at temperatures higher than $60^{\circ}C$. The Michaelis constant $(K_{m})\;and\;V_{max}$ for p-nitrophenyl palmitate were $21.8{\mu}M\;and\;270.3{\mu}M\;min^{-1}mg\;of\;protein^{-1}$, respectively. The enzyme was strongly inhibited by $Cd{2+},\;Co^{2+},\;Fe^{2+},\;Hg^{2+},\;EDTA$, 2-Mercaptoethalol. From these results, we suggested that lipase purified from Acinetobactor sp. B2 should be able to be used as a new enzyme for degradation of crude oil, one of the environmental contaminants.

• 생명과학회지
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• 제12권4호
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• pp.392-398
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• 2002

Lignocellulose 분해 이용을 위해 토양 등에서 lignin분해 능력이 우수한 세균을 분리 및 동정함으로서 방향족 화합물의 이용을 위한 생물전환의 기초를 확보하고자하였다. 토양 등의 시료로부터 38주의 리그닌 분해 균주를 분리하였다. 분리된 LG2를 공시 균주로 선정하여 형태학적, 배양학적 및 생리학적 특성을 조사한 결과 Pseudomonas sp. LG2로 명명하였다. 이 균주는 리그닌을 분해 할 수 있었으며, 리그닌 함유 배지에 배양하여 배양 분해 산물을 HPLC로 분석한 결과 다수의 방향족 화합물을 생산하였다 Poylacrylamide gel활성 분석에 의해서 3종류로 구성된 peroxidase가 조사되었다.

• Journal of Microbiology and Biotechnology
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• 제19권8호
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• pp.836-844
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• 2009

A denitrification bacterium was isolated from riverbed soil and identified as Ochrobactrum sp., whose specific enzymes for denitrification metabolism were biochemically assayed or confirmed with specific coding genes. The denitrification activity of strain G3-1 was proportional to glucose/nitrate balance, which was consistent with the theoretical balance (0.5). The modified graphite felt cathode with neutral red, which functions as a solid electron mediator, enhanced the electron transfer from electrode to bacterial cell. The porous carbon anode was coated with a ceramic membrane and cellulose acetate film in order to permit the penetration of water molecules from the catholyte to the outside through anode, which functions as an air anode. A non-compartmented electrochemical bioreactor (NCEB) comprised of a solid electron mediator and an air anode was employed for cultivation of G3-1 cells. The intact G3-1 cells were immobilized in the solid electron mediator, by which denitrification activity was greatly increased at the lower glucose/nitrate balance than the theoretical balance (0.5). Metabolic stability of the intact G3-1 cells immobilized in the solid electron mediator was extended to 20 days, even at a glucose/nitrate balance of 0.1.

• 한국미생물·생명공학회지
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• 제16권3호
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• pp.199-204
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• 1988

Naphthalene을 유일한 탄소원으로 이용하는 균을 분식 배양과 연속식 배양에 의해서 토양과 폐수로부터 분리하였다. 이 균은 Pseudomonas putida로 동정되었으며, 최적 pH와 온도는 각각 7.0과 3$0^{\circ}C$ 이었다. 분리된 균은 1,5-dihydroxynaphthalene을 naphthalene보다 더욱 잘 이용하였으며 benzoate와 salicylate도 이용하였다. 또한 catechol dl meta-분해경로를 통해서 분해되었으며, ampicillin, chloramphenicol, kanamycin, streptomycin에 대해서 강한 저항성을 지니고 있었으며, naphthalene의 분해에 관여하는 약 110kb 크기의 plasmid를 1개 지니고 있었다.

• BMB Reports
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• 제40권3호
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• pp.333-340
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• 2007

Gene encoding cyclodextrin glycosyltransferase (CGTase), from thermotolerant Paenibacillus sp. T16 isolated from hot spring area in northern Thailand, was cloned and expressed in E. coli (JM109). The nucleotide sequences of both wild type and transformed CGTases consisted of 2139 bp open reading frame, 713 deduced amino acids residues with difference of 4 amino acid residues. The recombinant cells required 24 h culture time and a neutral pH for culture medium to produce compatible amount of CGTase compared to 72 h culture time and pH 10 for wild type. The recombinant and wild-type CGTases were purified by starch adsorption and phenyl sepharose column chromatography and characterized in parallel. Both enzymes showed molecular weight of 77 kDa and similar optimum pHs and temperatures with recombinant enzyme showing broader range. There were some significant difference in pH, temperature stability and kinetic parameters. The presence of high starch concentration resulted in higher thermostability in recombinant enzyme than the wild type. The recombinant enzyme was more stable at higher temperature and lower pH, with lower $K_m$ for coupling reaction using cellobiose and cyclodextrins as substrates.

• 한국의류학회지
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• 제25권7호
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• pp.1270-1280
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• 2001

In this research of biodegradable polymers, it is essential to investigate the relation between biodegradability and molecular structure such as chemical constitution, hydrophilicity, molecular weight, crystallinity, chain orientation, and so on. It is also expected that hydrophilicity of polymer can affect biodegradability because biodegradation occurs with the help of enzymes and microorganisms. This study is to investigate the effect of hydrophilicity on biodegradability of polyesters. Hydrophilicity was varied by adding 5~30 mol% of amide groups, since amide groups are hydrophilic and used for improving thermal and mechanical properties. Surface energies and nitrogen contents by ESCA were measured to determine their hydrophilicity. The biodegradation was examined in activated sludge, enzyme and natural soil by $CO_2$evolution, TOC, weight loss, and observation through microscopy. The results showed that hydrophilicity of polyesteramide films increased with the addition of amide, PBAD series of shorter methylene units showed maximum hydrophilicity at 15~20 mol% of amide contents, but PBSE exhibited maximum values at 5~15 mol% of amide contents. The biodegradability increased as the hydrophilicty on surface increased. The biodegradation rate of PBAD series was higher than that of PBSE series. Therefore, it can be concluded that the addition of appropriate contents of hydrophile enhanced the biodegradability of aliphatic polyesters as well as their physical properties. Also, the experimental results revealed the relation between hydrophilicity and biodegradability of polyesteramides.

• Journal of Microbiology and Biotechnology
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• 제19권1호
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• pp.99-107
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• 2009

Strain PUPC1 produces an antifungal protease as well as plant growth promoting enzymes such as 1-aminocyclopropane-1-carboxylate (ACC) deaminase and phosphatase. Morphological, cultural, and physiological characteristics as well as 16S rRNA gene-sequence-based phylogenetic analysis confirmed the taxonomic affiliation of PUPC1 as Chryseobacterium aquaticum. The optimum growth of PUPC1 was observed at pH 6.0 and $30^{\circ}C$, and maximum protease production was observed in medium B amended with 1% tryptone, 0.5% sucrose, and 0.005% $MnCl_2$. The protease was purified by ammonium sulfate precipitation, Sephadex G-75 gel filtration chromatography, and electroelution from preparative SDS-PAGE. The protease had a molecular mass of 18.5 kDa. The optimum pH and temperature stability of the protease were pH 5.0-10.0 and temperature $40-70^{\circ}C$. Chryseobacterium aquaticum PUPC1 and its protease showed a broad-spectrum antifungal activity against phytopathogenic fungi. Strain PUPC1 also exhibited plant growth promoting traits. The objective of the present investigation was to isolate a strain for agricultural application for plant growth promotion and biocontrol of fungal diseases.

• Journal of Microbiology and Biotechnology
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• 제20권11호
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• pp.1597-1602
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• 2010

Chitinase is one of the most important mycolytic enzymes with industrial significance. This enzyme is produced by a number of organisms including bacteria. In this study, we describe the optimization of media components with increased production of chitinase for the selected bacteria, Stenotrophomonas maltophilia, isolated from soil. Different components of the defined media responsible for influencing chitinase secretion by the bacterial isolate were screened using Plackett-Burman experimental design and were further optimized by Box-Behnken factorial design of response surface methodology in liquid culture. Maximum chitinase production was predicted in medium containing 4.94 g/l chitin, 5.56 g/l maltose, 0.62 g/l yeast extract, 1.33 g/l $KH_2PO_4$, and 0.65 g/l $MgSO_4{\cdot}7H_2O$ using response surface plots and the point prediction tool of the DESIGN EXPERT 7.1.6 (Stat-Ease, USA) software.

• 한국환경농학회지
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• 제25권3호
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• pp.262-267
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• 2006

Increased application of glyphosate (Gly) in glyphosate-resistant (GR) soybean cropping systems may affect rhizospheric microorganisms including IAA-producing rhizobacteria (IPR) and their effect on the growth of soybean. This field experiment was conducted to assess IPR populations in the rhizosphere of GR soybean ('Roundup-Ready' DeKalb DKB38-52) treated with glyphosate and foliar amendment treatments such as $PT21^{(R)}$ (urea solution with N 21 %) and $Grozyme^{(R)}$ (Biostimulant: mixtures of micro nutrients and enzymes). Effects of herbicide, sampling date, and their interaction on total bacterial numbers were significant (P < 0.001, 0.001, 0.013, respectively). Total bacteria (TB) numbers were increased with glyphosate treatment at 20 d after application and highest TB populations were associated with $Grozyme^{(R)}$ application, possibly due to the additional substrate from this product. The IPR of the soybean rhizosphere was significantly affected by herbicide, sampling date, and the herbicide*foliar amendment interaction. The ratios of numbers of IPR to TB ranged from 0.79 to 0.99 across the sampling dates irrespective of treatments. IPR numbers were slightly hindered by glyphosate application regardless of foliar amendment.

• Journal of Microbiology and Biotechnology
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• 제16권2호
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• pp.295-298
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• 2006

Actinomycetes are ubiquitous Gram-positive soil bacteria and a group of the most important industrial microorganisms for the biosynthesis of many valuable secondary metabolites as well as the source of various bioconversion enzymes. Cytochrome P450 hydroxylase (CYP), a hemebinding protein, is known to be involved in the modification of various natural compounds, including polyketides, fatty acids, steroids, and some aromatic compounds. Previously, six different novel CYP genes were isolated from a rare actinomycetes called Sebekia benihana, and they were completely sequenced, revealing significant amino acid similarities to previously known CYP genes involved in Streptomyces secondary metabolism. In the present study, these six CYP genes were functionally expressed in Streptomyces lividans, using an $ermE^{*}$ promoter-containing Streptomyces expression vector. Among six CYP genes, two S. benihana CYP genes (CYP503 and CYP504) showed strong hydroxylation activities toward 7-ethoxycoumarin. Furthermore, the recombinant S. lividans containing both the S. benihana CYP506-ferredoxin genes as well as the S. coelicolor feredoxin reductase gene also demonstrated cyclosporin A hydroxylation activity, suggesting potential application of actinomycetes CYPs for the biocatalysts of natural product bioconversion.