• Research in Plant Disease
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• v.18 no.3
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• pp.225-230
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• 2012

Bacteriophages of Pectobacterium carotovorum subsp. carotovorum which causes soft rot on diverse vegetables had been isolated from 6 major Chinese cabbage cultivation areas in Korea. In order to isolate bacteriophages, total 15 different strains of P. carotovorum subsp. carotovorum isolated from nation-wide of Korea had been used as a host. When we tested 30 different soil samples individually from Pyeongchang and Taebaek with 15 different strains as a host, Taebek soil samples showed bacteriophage plaques with almost all different indicator strains but Pyeongchang soil samples showed plaques only with P. carotovorum subsp. carotovorum Pcc2 and Pcc3 strains. Especially, P. carotovorum subsp. carotovorum Pcc3 strain was able to produce plaques with almost all soil samples. Thus, this strain can be used as an indicator strain for P. carotovorum subsp. carotovorum bacteriophage screening. Electron microscope observation revealed P. carotovorum subsp. carotovorum bacteriophages isolated in Korea were belonged to three different families, Myoviridae, Siphoviridae and Podoviridae in order Caudovirales.

• The Korean Journal of Pesticide Science
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• v.20 no.4
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• pp.349-354
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• 2016

Triazole fungicides occupy an important portion in the global fungicide market and are relatively persistent in soil compared to the other fungicides, suggesting possible adverse effects of the fungicides on human health and environment. In this study, we tried to isolate microorganisms from orchard soils, which can decompose the triazole fungicides, tebuconazole, fluquinconazole, and difenoconazole. Only difenoconazole was completely degraded in the enrichment culture, from which several difenoconazole-degrading bacteria were isolated. They showed the same rep-PCR pattern thus only one strain, C8-2, was further studied. The strain was identified as Sphingomonas sp. C8-2 based on its 16S rRNA gene sequence and decomposed 100 mg/L of difenoconazole in a minimum medium to an unknown metabolite with a molecular weight of 296 within 24 hours. The inhibition effect of the metabolite against representative soil microorganisms significantly decreased compared to that of difenoconazole thus the bacterial strain is expected to be used for the detoxification of difenoconazole in soil and crop.

• Journal of the Korean GEO-environmental Society
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• v.12 no.5
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• pp.59-63
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• 2011

Ground dynamic parameter such as shear elastic modulus and damping ratio is a very important variable in design of ground-structure with repeated load and dynamic load. Shear elastic modulus and damping ratio on small strain below linear limit strain is constant regardless of strain. Shear elastic modulus as the maximum shear elastic modulus and damping ratio as the minimum damping ratio were considered. As a lot of experiment related to the maximum shear elastic modulus, which is in dynamic deformation characteristics, have been conducted, many factors including voiding ratio, over consolidation ratio(OCR), confining pressure, geology time, PI, and the number of load cycle affect to dynamic soil characteristic. However, the research of ground dynamic characteristic improved with grout is absent such as underground continuous wall construction, deep mixing method, umbrella arch method. In order to investigate the dynamic soil characteristics improved with grout, in this study, resonant column tests were performed with changing water content(20%, 25%, 30%) and injection ratio of grout(5%, 10%, 15%), cure time(7th day, 28th day) As a result, shear elastic modulus and damping ratio, which are ground dynamic parameter, are affected by the injection ratio of milk grout, cure time and water content.

• Microbiology and Biotechnology Letters
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• v.44 no.4
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• pp.512-521
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• 2016

A bacterial strain was isolated from a soil sample collected on Jeju Island, Korea. The strain, designated WJ-2, exhibited a high xylanase activity, whereas cellulase activity was not detected. The 16S rRNA gene sequence of WJ-2 was highly similar to type strains of the genus Streptomyces. A neighbor-joining phylogenetic tree based on 16S rRNA gene sequences showed that strain WJ-2 is phylogenetically related to Streptomyces atrovirens. Furthermore, DNA-DNA hybridization analysis confirmed that strain WJ-2 is a novel subspecies of Streptomyces atrovirens. The genomic DNA G+C content was 73.98 mol% and the major fatty acid present was anteiso-C15:0 (36.19%). The growth and xylanase production of strain WJ-2 were significantly enhanced by using soytone and xylan as nitrogen and carbon sources, respectively. Crude enzyme preparations from the culture broth of strain WJ-2 exhibited maximal total xylanase activities at pH 7.0 and $55^{\circ}C$. Thin-layer chromatography analysis revealed that the crude enzyme degrades beechwood xylan to yield xylobiose and xylotriose as the principal hydrolyzed end products.

• Korean Chemical Engineering Research
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• v.47 no.6
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• pp.788-794
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• 2009

Both strains of KD-1212 and DAH-1056 were isolated and identified from animal manure-contaminated soil by screening bacterial strains for the removal of sulfur compound-malodor with such substrate as sodium thiosulfate or free sulfur. Then the characteristics on the incubation of these microbes were observed under various incubating-condition such as pH, temperature, aerobic or anaerobic, substrate(sulfur compound) concentration, nitrogen and carbon source and rotating speed for mixing, and the optimum incubating condition was established. The optimum pHs of KD-1212 and DAH-1056 were 7.0 and 4.0, respectively, and their optimum temperatures were in the range of $30{\sim}35^{\circ}C$. Another autotrophic strain, ED-1138, was isolated from contaminated soil. The strain DAH-1056 excelled a strain Thiobacillus sp. IW in eliminating hydrogen sulfide during the process of malodor-biofiltration with a fixed strain. The characteristics on the incubation of strain KD-1212 were observed under various substrate-concentrations, nitrogen and carbon sources. KD-1212 favored glucose and maltose, and yeast extract as carbon sources and nitrogen source, respectively. The optimum concentrations of substrate and nitrogen source were 25 mM of sodium thiosulfate and 0.5% yeast extract, respectively for the growth of strain KD-1212.

• Korean Journal of Microbiology
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• v.35 no.2
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• pp.158-163
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• 1999

A ploygalacturonase-produchg yeast was isolated from Cheju soil by selective eivichment media. One strain which has the highesl activity of polygalacturonase was selected. The characle~ishcs of the strain CS-2 were as follows: CS-2 utilized xylose. sucrose, maltose, u.ehalose, cellobiose. melibiose, lactose, raffinose, inosiiol, dulicilol, and dextrose, but did not utilized galactose, nitrate. nit~te, and lysine. Growth of CS-2 was inhibited by cyclohexamide, 1% acetic acid, and high concenaation (over 50%) of glucose. It grew at $30^{\circ}C$ but did 'IIOL $35^{\circ}C$. The cell size ofthe strain CS-2 was 2.9 p ~ n in length and 1.3 $\mu$ in diameter. Vegetable reproductmn was multiple budding and ascospre was present I to 4. Pseudomycelia or true myceliua formation were not observed In any of the cullureq. These results suggest that strain CS-2 is most likely a strain related Cryptococcus spp. (Cryptococcu spp. CS-2). When polygalacturonase or ihe yeast was induced by addition of polygalactoronic acid, polygalacturonase activity was detected in culture supernatent. There was a peak of specific activity a1 he mid-stationary phase(3 days culture) of growth. Polygalacturonase specific activity of Crylmcoccus sp. CS-2 was 2.96 unitsling. The molecular weighl ol'polygalacturonase was showed to be 46 KDa by both SDS-PAGE and activity stailling.

• KSBB Journal
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• v.24 no.4
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• pp.334-340
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• 2009

For the isolation of a plant growth-promoting rhizobacteria, strain YK-5 was selected from approximately 400 thermostable strains isolated from special soil samples. Strain YK-5 produced an antifungal compound, and optimum carbon and nitrogen sources for the production of the antifungal compound were investigated against Aspergillus flavus as a test strain. Modified LB medium containing 1% peptone, 1% yeast extract and 5% black sugar was determined to be the optimal medium for growth and antifungal compound production. Culture broth of strain YK-5 potently inhibited growth of the phytopathogenic fungus Fusarium oxysporum KACC 40052 for 7 days. The plant growth-promotion function of strain YK-5 was tested against radish and rice in pot trials. Leaf number, plant height and root length in YK-5-treated radish markedly exceeded (> 60%) those of untreated radish. Leaf length and white rootlet development were markedly more prominent than in commercially-treated rice plants. Strain YK-5 was determined to be Bacillus subtilis YK-5 by physiological, chemotaxonomical, and phylogenetical analyses.

• Geotechnical Engineering
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• v.13 no.3
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• pp.5-20
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• 1997

A governing equation of uncoupled three dimensional finite strain theory of consolidation is presented. This equation is suitable for relatively thick layers, possessing large strain, non-linear material property, and variable permeability. A special numerical solution procedure has to be adopted for the finite difference scheme because the solution is not stable in using Forward-Time Centered-Space (FTCS) method and the governing equation is highly non-linear. The solution is capable of predicting settlement with respect to time. The results predicted by the developed method of analysis have been compared with those of experimental tests on different types of highly compressible soils with vertical wick drain. The uncoupled three dimensional finite strain theory of consolidation appears to predict settlement behavior well. A detailed comparison shows good agreement in terms of total settlement, and reasonable agreement with respect to time.

• Journal of the Korean Geotechnical Society
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• v.18 no.1
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• pp.29-39
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• 2002

In order to evaluate the behavior of overall range from small strain to failure, the triaxial compression tests with LVDTs were performed for local displacement measurements. According to the result it was possible to evaluate the total range behavior from 0.001% to 10% and both secant moduli of undisturbed and disturbed weathered soils had a similar result in the small slain level. The normalized shear moduli$(G/G_{max})$ in the undrained triaxial compression tests were similar to those of resonant column tests but the maximum shear moduli$(G/G_{max})$ were strongly affected by the ratio of saturation. As a result of parametric study a constitutive model with anisotropic hardening could predict the behavior of total strain range.

• Microbiology and Biotechnology Letters
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• v.27 no.6
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• pp.433-439
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• 1999

Among microorganisms isolated from soil, YJ-66 strain was the best producer of flocculant and was examined for flocculating ability in the active carbon and CaCl2. YJ-66 strain was the best producer of flocculant and was examined for flocculating ability in the active carbon and CaCl2. YJ-66 strain was identified to be a species belonging to the genus Achromobacter. The optimum culture condition for production of bioflocculant with the isolated strain was for 72hrs at 3$0^{\circ}C$ and pH7.5. The favorable carbon, nitrogen sources and inorganic salts for production of the flocculant were sucrose, peptone, MgSO4 and KH2PO4, whose optimal concentrations were 2%. 0.067%, 0.1% and 0.1%, respectively. Addition of the carbon and inorganic salts significantly increased the production of flocculant. Compositions of optimized culture medium for bioflocculant production by Achromobacter sp. YJ-66 were 2% sucrose, 0.067% peptone, 0.1% MgSO4 and 0.1% KH2PO4 in initial pH 7.5 during at 3$0^{\circ}C$ for 72hrs.