• Microbiology and Biotechnology Letters
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• v.25 no.6
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• pp.580-585
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• 1997

We selected two mutants namely strain D5 and Nu23 by mutagenesis of anthracycline producing Streptomyces: the former is an $\varepsilon$-rhodomycinone overproducing mutant selected from Streptomyces sp. C5, a baumycin producer and the latter, a blocked mutant of early pathway for doxorubicin biosynthesis obtained from Streptomyces peucetius ATCC 27952, a doxorubicin producer. The mutant strain Nu23 does not produce anthracycline metabolites but retains the most of enzyme activities converting aklavinone to doxorubicin and the mutant strain D5 produced $\varepsilon$-rhodomycinone at a level of 150 $\mu$g/ml. These strains were grown separately in NDYE medium and each was mixed at day 3 by equal volume of culture broth but the quantity of doxorubicin produced was far below an estimation based on the level of $\varepsilon$-rhodomycinone normaly produced by the strain D5. On the other hand doxorubicin was reached at maximum level after 4 days in the mixed culture condition which was composed of culture broth of strain D5 grown for 6 day and that of strain Nu23 grown for 3 day. It was turned out that the growth of mutant strain D5 was inhibited by the accumulation of daunorubicin and doxorubicin in mixed culture broth, which cause the limitation of $\varepsilon$-rhodomycinone.

• Structural Engineering and Mechanics
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• v.56 no.4
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• pp.589-603
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• 2015

The mixed-mode stress intensity factors of 2-D angled cracks are evaluated by Petrov-Galerkin natural element (PG-NE) method in which Voronoi polygon-based Laplace interpolation functions and CS-FE basis functions are used for the trial and test functions respectively. The interaction integral is implemented in a frame of PG-NE method in which the weighting function defined over a crack-tip integral domain is interpolated by Laplace interpolation functions. Two Cartesian coordinate systems are employed and the displacement, strains and stresses which are solved in the grid-oriented coordinate system are transformed to the other coordinate system aligned to the angled crack. The present method is validated through the numerical experiments with the angled edge and center cracks, and the numerical accuracy is examined with respect to the grid density, crack length and angle. Also, the stress intensity factors obtained by the present method are compared with other numerical methods and the exact solution. It is observed from the numerical results that the present method successfully and accurately evaluates the mixed-mode stress intensity factors of 2-D angled cracks for various crack lengths and crack angles.

• Journal of Ocean Engineering and Technology
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• v.12 no.2 s.28
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• pp.57-64
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• 1998

This study is concerned with criterion for membrane to shell conversion in two-dimensional elastic-plastic finite element analysis using membrane/shell mixed element. It is well known that in the sheet metal forming some parts of the sheet deform under almost pure stretching (membrane) conditions, whereas other parts in contact with sharp tooling surfaces can develop significant bending strains. The membrane analysis has a short computational time however, in the membrane analysis the bending effects can not be condidered at all. On the other hand, the shell analysis allows the consideration of bending effects, but involves too much computational time. So Onatel),2), Yang et al3),4) developed the membrane/shell mixed element. Onate introduced the energy ratio parameter and Yang et al introduced the ratio of thickness to radius of curvature as the criterion. In the present study we propose a new criterion by using the angle between both side elements in the nodal point.

• KSBB Journal
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• v.18 no.6
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• pp.466-472
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• 2003

Several microorganisms were isolated and characterized for the development of fermentation accelerator of animal manure. Firstly, 61 species were isolated from rice bran extract. Secondly, five strains of microorganisms were screened by the analysis of hydrolysis activities for organic compounds including protease, cellulase, amylase, and lipase. From a deodorization test for ammonia gas using the isolated strains, finally three bacterial strains were selected (NA 2, 12, 15). The selected strains, NA 2 and 15 were identified as Bacillus acidocaldarius and Planococcus sp. respectively. The media composition of key nutrients and pH for the mixed culture of the three selected strains were optimized using an experimental design method (response surface method) as follows : beef extract (4.59g/L), peptone (8.72g/L) and pH 6.3. Consequently, the isolated microorganisms seem to have potential applicability in the animal manure treatment.

• Journal of Microbiology
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• v.33 no.3
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• pp.208-214
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• 1995

The effects of various 2, 4-D-degradative plasmids on the axenic growth patterns, the degradation phenotypes, and the competitiveness of different host bacteria were evaluated in liquid cultures; the organisms and plasmids used were Alcaligenes eutrophus JMP134/pJP4, Alcaligenes paradoxus/p2811, Pseudomonas pickettii/p712, pJP4, and p712 or p 2811 exhibited very different restriction fragment profiles in restriction endonuclease digests. These plasmids were transferred to the recipients (P. cepacia and Alcaligenes JMP228) at relatively high frequencies ranging from 8.9 $\times$ 10$^3$ to 1.6 $\times$ 10$^5$ per donar cell. In the axenic liquid cultures the fast-growing strains, such as P. pseudomallei/p745 and P. cepacia/pJP4, exhibited short lag periods, high specific growth rates, and high relative fitness coefficients, while the slow-growing strains, such as P. pickettii/p712 and A. paradoxus/p2811, had long lag periods, low specific growth rates, and low relative fitness coefficients. Depending on the type of plasmid containing the genes for the 2, 4-D pathway, some transconjugants exhibited intermediate grwoth patterns between the fast-growing strains and the slow-growing strains. The plasmid and plasmid-host interactions determined specific growth rate and lag time, respectively, which were shown to be principal determinants of competitiveness among the strains, but relative fitness coefficient derived from the axenic culture was not always predictive for the mixed culture condition.

• Korean Journal of Food Science and Technology
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• v.32 no.2
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• pp.424-430
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• 2000

The purpose of the study was to investigate effect of addition of mutant strains of both Leuconostoc mesenteroides and Leu. paramesenteroides on extending shelf-life of Kimchi. The mutant strains have an increased adipic acid resistance in comparison with that of their paired wild types. Addition of both strains was more effective than that of one strain alone to extend shelf-life of Kimchi. The optimal amount of inoculation was determined as 0.005% of the two mixed mutant strains with a ratio of 1 : 10, Leu. mesenteroides : Leu. paramesenteroides based on the results of acidification and organoleptic tests.

• Korean Journal of Medicinal Crop Science
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• v.14 no.6
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• pp.336-341
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• 2006

The endophytic bacteria were isolated from the rusty-root ginseng. This isolated bacteria were occurred the rusty-root ginseng with artificial inoculation. For the suppressing of rusty-ginseng, disinfectants, antibiotics, kitosan, micro-organisms and metabolites were tested to isolated endophytic bacterium. All of the isolated bacteria strains were sensitive sodium hypochlorite, however, some of isolated bacteria lines were sensitive to other tested materials. For example, D (didecyl dimethyl ammonium bromide), CIO$_2$, ODDA (octyldecyl dimethyl ammonium chloride + diocyul dimethyl ammonium chloride + alkyl diethyl benzyl ammonium chloride), GD (glutaraldehyde + dimethy cocobenzyl ammonium chloride) suppressed some of bacteria strains. Otherwise, some of antibiotics (e.g. ampicillin, chloramphenicol, erythromycin, kanamycin, neomycin, rifampin, streptomycin, tetracycline) were sensitive to the isolated bacteria strains. All of isolated bacteria strainswere inhibitive to the mixed formation with neomycin and streptomycin, and neomycin and tetracycline. Both sodium hypochlorite and antibiotic mixing of neomycin and tetracycline were effective to prevention of rusty-root ginseng of sub-merging ginseng in the ginseng field.

• Journal of Microbiology and Biotechnology
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• v.13 no.6
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• pp.942-948
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• 2003

Soil samples were obtained from 5 sites contaminated with polycyclic aromatic hydrocarbons (PAHs). These soil samples were cultured in using phenanthrene as a sole carbon and energy source, and 36 strains of phenanthrene-degrading bacteria were isolated from 3 sites. Most of them degraded 500 ppm of phenanthrene within 8 to 10 days, and these isolates could degrade a few other PAHs other than phenanthrene. Their genotypes were determined by restriction digests of the l6S rRNA genes [amplified ribosomal DNA restriction analysis (ARDRA)]. It was found that all the phenanthrene degrading isolates were included in 4 ARDRA types, and they showed a strict site endemism. l6S rDNAs of 12 strains selected from different sites were sequenced, and they were all confirmed as Sphingomonas strains. Their l6S rDNA sequences were compared for phylogenetic analysis; their sequence showed a similar result to ARDRA typing, thus indicating that these heterotrophic soil bacteria are not regionally mixed. In addition, it was found that the microbial diversity among sampling sites could be monitored by l6S rDNA PCR-RFLP pattern alone, which is simpler and easier to perform, without l6S rDNA sequence analysis.

• Microbiology and Biotechnology Letters
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• v.39 no.2
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• pp.175-181
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• 2011

Kimchi is a group of traditional fermented vegetable foods in Korea and known to be the product of a natural mixed-fermentation process carried out principally by lactic acid bacteria (LAB). According to microbial results based on conventional identification, Leuconostoc mesenteroides and Lactobacillus plantarum were considered to be responsible for the good taste and over-ripening of kimchi, respectively. However, with the application of phylogenetic identification, based on 16S ribosomal RNA gene similarities, a variety of Leuconostoc and Lactobacillus species not detected in the previous studies have been isolated, together with a species in the genus Weissella. Additionally, Lactobacillus sakei has been accepted as the most populous LAB in over-ripened kimchi. In this study, Leuconostoc and Weissella species inhibiting the growth of Lb. sakei were isolated from kimchi for future applications to do with kimchi fermentation. From 25 kimchi samples, 378 strains in the genera Leuconostoc and Weissella were isolated and 68 strains identified as Lc. mesenteroides, Lc. citreum, Lc. lactis, W. cibaria, W. confusa, and W. paramesenteroides exhibited growth inhibition against Lb. sakei. Most of the strains also had antagonistic activities against Lb. brevis, Lb. curvatus, Lb. paraplantarum, Lb. pentosus, and Lb. plantarum. Their antagonistic activities against Lb. sakei were more remarkable at lower temperatures of incubation.

• YAKHAK HOEJI
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• v.41 no.4
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• pp.462-472
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• 1997

In this approach, the antimicrobial activities of the compounds were compared with the ${\beta}$-lactam antibiotics against ${\beta}$-lactamase producing strains in vitro. Heteroc yclyl exomethylenepenam derivatives were several numbers of 6-exomethylenepenam sodiums (CH1240, CH1245, CH1250, CH2140, CH2145, CH2150). The inhibitory concentraion assay of six compounds were compared with clavulanic acid, sulbactam, tazobactam. Clavulanic acid, sulbactam and tazobactam are used as inhibitors of a variety of plasmid-mediated beta-lactamases. In vitro ${\beta}$-lactamase inhibitory assay, CH1240 and CH2140 were more active than clavulanic acid, sulbactam and tazobactam against ${\beta}$-lactamases overally. And in vitro comparative antimicrobial susceptibility test of six inhibitors were performed with mixed forms of ampicillin, cefotaxime, amoxicillin, ticarcillin, piperacillin, cefoperazone against ${\beta}$-lactamase producing 31 species strains. Consequently CH2140 and CH1240 among the six compounds enhanced the activity of the ${\beta}$-lactams for 31 ${\beta}$-lactamase producing strains.