• Journal of Microbiology and Biotechnology
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• 제17권12호
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• pp.1991-1995
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• 2007

O-Methylation is a common substitution reaction found in microbes as well as in mammalians. Some of the O-methyltransferases (OMTs) have broad substrate specificity and could be used to methylate various compounds. DnrK from Streptomyces peucetius encodes an anthracycline 4-O-methyltransferase, which uses carminomycin as a substrate, and its crystal structure has been determined. Molecular docking experiments with DnrK using various flavonoids were successfully conducted, and some of the flavonoids such as apigenin and genistein were predicted to serve as substrates. Based on these results, O-methylations of various flavonoids with the DnrK were successfully carried out. The methylation position was determined to be at the hydroxyl group of C7. Important amino acid residues for the enzymatic reaction of DnrK with apigenin could be identified using site-directed mutagenesis. Molecular docking could be useful to predict the substrate specificity ranges of other OMTs.

• Biotechnology and Bioprocess Engineering:BBE
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• 제9권2호
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• pp.137-142
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• 2004

In this study, a simple procedure is described for patterning biotin on a glass substrate and then selectively immobilizing proteins of interest onto the biotin-patterned surface. Microcontact printing (CP) was used to generate the micropattern of biotin and to demonstrate the selective immobilization of proteins by using enhanced green fluorescent protein (EGFP) as a model protein, of which the C-terminus was fused to a core streptavidin (cSA) gene of Streptomyces avidinii. Confocal fluorescence microscopy was used to visualize the pattern of the immobilized protein (EGFP-cSA), and surface plasmon resonance was used to characterize biological activity of the immobilized EGFP-cSA. The results suggest that this strategy, which consists of a combination of $\mu$CP and cSA-fused proteins. is an effective way for fabricating biologically active substrates that are suitable for a wide variety of applications. one such being the use in protein-protein assays.

• Molecules and Cells
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• 제37권10호
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• pp.727-733
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• 2014

Spinosyns A and D are potent ingredient for insect control with exceptional safety to non-target organisms. It consists of a 21-carbon tetracyclic lactone with forosamine and tri-Omethylated rhamnose which are derived from S-adenosyl-methionine. Although previous studies have revealed the involvement of metK1 (S-adenosylmethionine synthetase), rmbA (glucose-1-phosphate thymidylyltransferase), and rmbB (TDP-D-glucose-4, 6-dehydratase) in the biosynthesis of spinosad, expression of these genes into rational screened Saccharopolyspora spinosa (S. spinosa MUV) has not been elucidated till date. In the present study, S. spinosa MUV was developed to utilize for metabolic engineering. The yield of spinosyns A and D in S. spinosa MUV was $244mgL^{-1}$ and $129mgL^{-1}$, which was 4.88-fold and 4.77-fold higher than that in the wild-type ($50mgL^{-1}$ and $27mgL^{-1}$), respectively. To achieve the better production; positive regulator metK1-sp, rmbA and rmbB genes from Streptomyces peucetius, were expressed and co-expressed in S. spinosa MUV under the control of strong $ermE^*$ promoter, using an integration vector pSET152 and expression vector pIBR25, respectively. Here-with, the genetically engineered strain of S. spinosa MUV, produce spinosyns A and D up to $372/217mgL^{-1}$ that is 7.44/8.03-fold greater than that of wild type. This result demonstrates the use of metabolic engineering on rationally developed high producing natural variants for the production.

• Geomechanics and Engineering
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• 제12권5호
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• pp.753-770
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• 2017

The coagulation or flocculation of cohesive clay suspensions is one of the most widely used treatment technologies for contaminated water. Flocculated clay can transport pollutants and nutrients in ground water. Coagulants are used to accelerate these mechanisms. However, existing coagulants (e.g., polyacrylamide, polyaluminum chloride) are known to have harmful effects in the environment and on human health. As an alternative, eco-friendly coagulant, this study suggests ${\varepsilon}-polylysine$, a cationic biopolymer fermented by Streptomyces. A series of sedimentation experiments for various ${\varepsilon}-polylysine$ concentrations were performed, and the efficiency of sedimentation with ${\varepsilon}-polylysine$ was estimated by microscopic observation and light absorbance measurements. Two types of sedimentation were observed in the experiments: accumulation sedimentation (at 0.15%, 0.20%, 0.25% ${\varepsilon}-polylysine$) and flocculation sedimentation (at 0%, 0.1%, 0.5%, 1.0%, 2.0% ${\varepsilon}-polylysine$). These sedimentation types occur as a result of the concentration of counter ions. Additionally, the performance of ${\varepsilon}-polylysine$ was compared with that of a previously used environmentally friendly coagulant, chitosan. The obtained results indicate that flocculation sedimentation is appropriate for contamination removal and that ${\varepsilon}-polylysine$ functions more efficiently for clay removal than chitosan. From the experiments and analysis, this paper finds that polylysine is an alternative eco-friendly coagulant for removing chemical contaminants in groundwater.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 춘계학술발표대회
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• pp.279-282
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• 2000

S. lincolnensis 배양시 나타나는 거품의 문제를 해결하기위해 UP-1과 OP-1배지에 소포제 종류를 PPG, PEG 및 CA-110을 첨가하여 실험하였다. OP-1배지를 이용한 플라스크 배양의 경우 PPG와 PEG 각각 402 mg/L, 394 mg/L로 높은 Lincomycin 생산농도를 나타내었으나, UP-1배지의 경우 대조구에 비해 Lincomycin 생산농도는 큰 차이가 없었다. 두 가지 배지에서 소포제 농도의 변화에 대한 Lincomycin생산을 통계처리한 결과는 실험한 농도 범위에서 큰 차이를 나타내지 않았다. 충분한 산소공급은 Lincomycin 생산에 필수적이고, rpm의 변화에 따른 실험 결과 300 rpm의 경우 가장 효과적이었다. 발효조에서 PPG 농도 5, 1, 0.5 g/L를 첨가하여 발효한 결과 상당한 차이를 나타내었다. Lincomycin 생산을 위한 소포제로서 PPG가 가장 좋았으며 농도는 0.5 g/L가 적절하였다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2005년도 생물공학의 동향(XVI)
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• pp.152-156
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• 2005

본 연구에서 수행한 avermectin 생산을 위한 배지 최적화에서 기존의 총 avermectin의 함량 10 mg/L를 470 mg/L까지 증가시켰으며, 이 중 광범위 활성을 가지는 avermectin B1도 50%에 달했다. 최적화된 배지 조성은 50 g/L fructose, 30 g/L malt extract, 5 g/L casamino acid, 2.5 g/L PEG 3,350, and 1 g/L $K_{2}HPO_{4}$이다. $K_{2}HPO_{4}$와 fructose, malt extract가 avermectin 생합성에 크게 작용하는 것으로 추정된다.

• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 2003년도 정기총회 및 추계학술발표회
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• pp.69.1-69
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• 2003

RSH (relA/spoT homolog) has been known to determine the level of guanosine tetraphosphate (ppGpp) and guanosine pentaphosphate (pppGpp), which are the effector nucleotide of the prokaryotic stringent response and also play a role in antibiotic production and differentiation in Streptomyces species but not a little in eukaryotic organism, especially in plant. Salicylic acid (SA), a critical signal molecule of establishing systemic acquired resistance (SAR), could induce SAR in Pepper (Capcicum annuum) against Phytophthora capsici. And the extent of SAR induction was in proportion to the dosage of SA (or BTH). Suppression subtractive hybridization (SSH), a PCR-based method for cDNA subtraction, was carried out between SA-treated and non-SA-treated pepper leaves to isolate genes which may be responsible for defense signaling against pathogens. Early upregulated gene was selected from reverse northern and kinetics of SSH-genes transcripts in SA-treated pepper leaves upon SA treatment. Full-length cDNA of the gene (PepRSH； Pepper RelA / SpoT homolog) had an open reading frame (ORF) of 2166 bp encoding a protein of 722 amino acids and a significant homology with (p)ppGpp phosphohydrolase or synthetase. Genomic DNA gel blot analysis showed that pepper genome has at least single copy of PepRSH. PepRSH transcripts was very low in untreated pepper leaves but strongly induced by SA and methyljasmonic acid (MeJA), indicating that PepRSH may share common SA and MeJA-mediated signal transduction pathway Functional analysis in E. coli showed PepRSH confers phenotypes associated with (p)ppGpp synthesis through a complementation using active site mutagenesis.

• The Plant Pathology Journal
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• 제15권1호
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• pp.14-20
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• 1999

Twenty isolates of Helminthosporium species were obtained from various grass plants and tested for controlling efficacy on the development of plant diseases. An isolate of Helminthosporium sp. TP-4 was chosen and six antibiotic substances were purified from cultures of the fungus by repeated silica gel column chromatography and preparative thin-layer chromatography. They were identified as ophiobolin a, 6-epiophiobolin A, 3-anhydroophiobolin A, 3-anhydro-6-epiophiobolin A, iphiobolin B, and iphiobolin I mainly by mass spectrometry and nuclear magnetic resonance spectrometry. Ophiobolins inhibited the growth of a grampositive bacterium Streptomyces griseus, but were not active against gram-negative bacteria. They also showed an antifungal activity. In in vivo tests, iphiobolin B exhibited potent controlling activities against rice blast, tomato late blight, and wheat leaf rust with control values more than 90% and 70% at concentration of $500\mu\textrm{m}$/ml and 100 ${\mu}{\textrm}{m}$/ml. Ophiobolin A and 6-epiophiobolin A controlled the development of wheat leaf rust more than 80% at concentrations of 100 /ml and $500\mu\textrm{m}$/ml respectively. 3-Anhydro-6-epiophiobolin A was not active against any plant disease. On the other hand, the A-series ophiobolins other than 3-anhydroophiobolin A showed stronger phytotoxic activity in a leaf-wounding assay using 8 plant species than those of 3-anhydroophiobolin A, ophiobolin B, and ophiobolin I. The results indicate that there is little correlation between antifungal activity and phytotoxicity of ophiobolins.

• Mycobiology
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• 제48권1호
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• pp.37-43
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• 2020

A serious leaf disease caused by Colletotrichum dematium was found during the cultivation of Sarcandra glabra in Jingxi, Rong'an, and Donglan Counties in Guangxi Province, which inflicted huge losses to plant productivity. Biological control gradually became an effective control method for plant pathogens. Many studies showed that the application of actinomycetes in biological control has been effective. Therefore, it may be of great significance to study the application of actinomycetes on controlling the diseases caused by S. glabra. Strains of antifungal actinomycetes capable of inhibiting C. dematium were identified, isolated and screened from healthy plants tissues and the rhizospheres in soils containing S. glabra. In this study, 15 actinomycetes strains were isolated and among these, strains JT-2F, DT-3F, and JJ-3F, appeared to show antagonistic effects against anthracnose of S. glabra. The strains JT-2F and DT-3F were isolated from soil, while JJ-3F was isolated from plant stems. The antagonism rate of strain JT-2F was 86.75%, which was the highest value among the three strains. Additionally, the JT-2F strain also had the strongest antagonistic activity when the antagonistic activities were tested against seven plant pathogens. Strain JT-2F is able to produce proteases and cellulase to degrade the protein and cellulose components of cell walls of C. dematium, respectively. This results in mycelia damage which leads to inhibition of the growth of C. dematium. Strain JT-2F was identified as Streptomyces tsukiyonensis based on morphological traits and 16S rDNA sequence analysis.

• Journal of Microbiology and Biotechnology
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• 제16권1호
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• pp.145-148
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• 2006

A new functional lipolytic enzyme (AT4) has recently been found from Agrobacterium tumefaciens C58 Cereon using a genome-wide approach. The enzyme has some sequence similarity to E. coli acetyl hydrolase, Emericella nidulans lipase, Moraxella sp. lipase, Acinetobacter lwoffii esterase, and Streptomyces hygroscopicus acetyl hydrolase. However, the sequence similarities are very low (less than $25\%$), suggesting that it is a new lipase/esterase enzyme. ill the present study, intact cell of the A. tumefaciens strain was shown to have lipolytic activity on a tributyrin-LB plate. The AT4 gene was then expressed at a high level in E. coli BL21 (DE3) cells and the enzyme was purified simply by Ni-NTA column chromatography. The purified enzyme showed hydrolytic activity toward p-nitrophenyl caproate, but not toward olive oil, suggesting that the AT4 enzyme was a typical esterase rather than lipase. AT4 esterase had a maximum hydrolytic activity at $45^{\circ}C$ and pH 8.0, when p-nitrophenyl caproate was used as a substrate. It was relatively stable up to $40^{\circ}C$ and at pH 5.0-9.0. Calcium ion and EDT A did not affect the activity and thermal stability of the enzyme. As for substrate specificity, AT4 enzyme could rapidly hydrolyze acetyl and butyl groups from p-nitrophenyl esters and 1-naphthyl esters. In addition, it also released acetyl residues from acetylated glucose and xylose substrates. Therefore, this new esterase enzyme might be used as a biocatalyst in acetylation and deacetylation reactions performed in the fine chemical industry.