• Korean Journal of Plant Tissue Culture
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• v.25 no.5
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• pp.329-333
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• 1998

$\beta$-Glucuronidase (GUS) gene of Escherichia coli was introduced into sweet potato (Ipomoea batatas (L.) Lam.) cells by particle bombardment and expressed in the regenerated plants. Microprojectiles coated with DNA of a binary vector pBI121 carrying CaMV35S promoter-GUS gene fusion and a neomycin phosphotransferase gene as selection marker were bombarded on embryogenic calli which originated from shoot apical meristem-derived callus and transferred to Murashige and Skoog (MS) medium supplemented with 1 mg/L 2,4-dichlorophenoxyacetic acid and 100 mg/L kanamycin. Bombarded calli were subcultured at 4 week intervals for six months. Kanamycin-resistant calli transferred to MS medium supplemented with 0.03 mg/L 2iP, 0.03 mg/L ABA, and 50 mg/L kanamycin gave rise to somatic embryos. Upon transfer to MS basal medium without kanamycin, they developed into plantlets. PCR and northern analyses of six regenerants transplanted to potting soil confirmed that the GUS gene was inserted into the genome of the six regenerated plants. A histochemical assay revealed that the GUS gene was preferentially expressed in the vascular bundle and the epidermal layer of leaf, petiole, and tuberous root.

• Korean Journal of Microbiology
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• v.30 no.6
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• pp.438-443
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• 1992

Thirteen strains of Bacillus thuringiensis were isolated from soil in Korea and characterized. The all strains produced parasporal crystals and spores in their cells. Two strains had bipyramidal crystals, seven strains contianed round ones and four strains had unregular ones. Only minor biochemical characteristics of the thirteen isolates were different and distinctive, however general characteristics were similar to the known serotypes of B. thuringiensis. Two strains were resistant to ampicilin. Three strains were resistant to bacitracin, six strains were resistant to cephalothin, two strains were resistant to colistin, HL-68 strain was resistant to gentamycin, HL-67 strain was resistant to kanamycin and HL-71 was resistant to tetracycline. Two strains were resistant to penicillin G. Four strains were toxic to Bombyx mori larvae and eleven strains were toxic to Culex pipiens larvae.

• The Journal of the Korean Society for Microbiology
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• v.13 no.1
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• pp.31-36
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• 1978

Twenty strains of Salmonella paratyphi A, 55 of S. typhi, 7 of Shigella flexneri, and 14 of Sh. sonnei which were isolated in Taegu area in 1977, were tested for the susceptibility to antimicrobial drugs. All strains of S. paratyphi A were resistant to sulfisomidine(Sa), but none was resistant to chloramphenical(Cm), tetracycline(Tc), streptomycin(Sm), ampicillin, nalidixic acid, kanamycin, gentamicin, amikacin, 1:20 mixture of trimethoprim and sulfamethoxazole, carbenicillin, cephaloridine, and rifampicin. Only one strain. of S. typhi was multiply resistant to Cm, Tc, Sm, and Sa, but all strains were susceptible to the other drugs tested. The resistant strain carried R plasmid; R(Cm Tc Sm Sa). All strains except one were highly resistant to Cm, Tc, Sm, and Sa, and all except one of multiply resistant strains carried R plasmid; R(Cm Tc Sm Sa).

• Korean Journal of Veterinary Research
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• v.17 no.1
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• pp.5-8
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• 1977

One hundred and fifty seven Escherichia coli strains isolated from 18 cattle (9 dairy cattle received penicillin, streptomycin (SM) or sulfadimethoxine for treatment of diseases and 9 Korean native cattle not received antibiotics) were studied for the drug resistance and distribution of R factors. Of 88 E. coli strains isolated from cattle not received antibiotics, only 1 strain was resistant to SM, but about 46 per cent of 69 E. coli strains isolated from cattle received antibiotics were resistant to SM, tetracycline (TC), ampicillin (AP), kanamycin (KM), chloramphenicol (CM), and sulfisomidine (Su), alone or in combination thereof. Of resistant strains, about 72% were resistant to three or more antibiotics, but 28% were found to singly resistant. The most frequent resistant pattern was triple resistance to AP, KM and Su (37.6%), and quadruple one to SM, TC, CM and Su (12.5%). About 28% of resistant strains carried R factors which were transferable to E. coli ML 1410 $NA^r$ by conjugation.

• Korean Journal of Veterinary Research
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• v.17 no.1
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• pp.1-4
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• 1977

Two hundred and twenty-seven strains of Escherichia coli isolated from 25 hens (12 hens received tetracycline neomycin and sulfadimethoxine, and 13 hens not received antibiotics) were studied for the drug resistance and distribution of R factors. About 74 per cent of E. coli strains isolated from hens of a herd received antibiotics were resistance to tetracycline (TC) streptomycin (SM), chloramphenicol (CM), kanamycin (KM), ampicillin (AP) and sulfisomidine (Su), alone or in combination thereof, but only a hen among a herd not received antibiotics excreted E. coli resistant to TC and SM. Among resistant strains, about 7% were found to be resistant to TC and SM, whereas 93% were resistant to three or more antibiotics. The most common pattern was the quadruple resistant to SM, TC, KM and Su (28.7%), and followed by triple ones to SM, TC and Su (25.3%), and SM, TC and KM (24.7%). About 84% of resistant strains carried R factors which were transferable to the recipient by conjugation.

• Korean Journal of Plant Tissue Culture
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• v.26 no.4
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• pp.281-287
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• 1999

Codonopsis lanceolata ("Deoduck" in Korea) is a perennial herb, and belongs to family, Campanulaceae. Its taproot is used a good source of a wild vegetable as well as an herbaceous medicine. In this study, to develop a bialaphos-resistant transgenic Codonopsis, seed germination mechanism and somatic embryogenesis of the plant were investigated, and Agrobacterium-mediated transformation with bar gene encoding phosphinothricin acetyltransferase (PAT) was performed. Attempt were made to regenerate plant from cells via somatic embryogenesis. When the cotyledons, nodes and leaf disks were cultured on MS medium containing 2,4-D and zeatin, embryogenic calli were induced. Upon transferring the somatic embryos to N6 solid medium without plant growth regulators, they developed into plantlets under continuous illumination. All plants were dead on MS basal medium containing 10 mg/L phosphinothricin (PPT) and Basta, respectively. The explants did not produce calli in the medium containing 200 mg/L kanamycin. The explants were cocultured with Agrobacterium tumefaciens for 2 days, and transformants were selected in MS basal medium containing 1.0 mg/L 2,4-D, 100 mg/L kanamycin and 500 mg/L carbenicillin. After the selection, embryogenic calli were induced and then somatic embryos were produced by subsequent subculturing. The somatic embryos were germiated on N6 basal medium containing 200 mg/L kanamycin and 500 mg/L carbenicillin. PCR analysis showed that nptII and bar genes were introduced in the Deoduck transformants. After the confirmation of bar gene expression in RNA and protein level, the transgenic Deoduck will be used to study the genetics of filial generation with the herbicide control gene, bar.gene, bar.

• Microbiology and Biotechnology Letters
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• v.21 no.2
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• pp.107-112
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• 1993

The optimal conditions for protoplast fusion between the cells of kanamycin resistant Lactobacillus bulgaricus IFO 13593 and those of lincomycin resistant Lactobacillus helveticus IAM 12090 were investigated in this study. The highest fusion frequency of 9.1*10-4 was obtained when protoplast fusion was carried out for 0.5 min using 40% PEG 4000 solution as a cell fusion stimulant and subsequent post-PEG-incubation was undergone at 30 for 30 min in the PPI medium.

• Journal of Plant Biotechnology
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• v.31 no.4
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• pp.267-271
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• 2004

Transformed sweetpotato (Ipomoea batatas (L.) Lam. cv. Yulmi) plants were developed from embryogenic calli following Agrobacterium tumefaciens-mediated transformation. A. tumefaciens strain EHA105/pCAMBIA2301 harboring genes for intron $\beta$-glucuronidase (GUS) and kanamycin resistance. Transient expression of GUS gene was found to be higher when embryogenic calli were co-cultivated with Agrobacterium for 2 days. The co-cultured embryogenic calli transferred to selective MS medium containing 1mg/L 2,4-D, 100mg/L kanamycin, and 400mg/L claforan. These embryogenic calli were subcultured to the same selection medium at 4 weeks interval. Kanamycin-resistant calli transferred to hormone-free MS medium with kanamycin gave rise to somatic embryos and then converted into plantlets in the same medium. Southern blot analysis confirmed that the GUS gene was inserted into the genome of the sweetpotato plants. A histochemical assay revealed that the GUS gene was preferentially expressed in the leaf, petiole, and vascular tissue and tip of root.

• Korean Journal of Veterinary Research
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• v.17 no.2
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• pp.73-78
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• 1977

The distribution of coliform population and drug-resistant coliforms in Shinchun water during April to August in 1976 and R factors in resistant strains were studied. The mean coliform population in the stream water was 361 organisms per 0.1ml and 53.5% of total coliforms were fecal coliforms. Thritynine and a half percent of total coliforms were streptomycin (SM) resistant to one or more of following antibiotics; tetracycline (TC), chloramphenicol (CM), ampicillin (AP) and kanamycin (KM). The most frequent resistant pattern was triple resistance to SM, TC and AP (23.8%) and followed by quadruple one to SM, TC, CM and AP (17.5%). About 87 percent strains carried R factors which were transferable by conjugation to E. coli ML 1410 or S. typhimurium LT 2.

• The Journal of the Korean Society for Microbiology
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• v.13 no.1
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• pp.63-73
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• 1978

28 strains of Enterococci isolated at doctorless areas in Korea from Oct. 1976 through Mar. 1977 and 30 strains of Enterococci isolated at Seoul National University Hospital from Sep. 1976 through Dec. 1976 were examined for susceptibilities to 14 antimicrobial agents by agar dilution method. The susceptibilities of two groups to each antimicrobial agent were compared and incidence of resistant strains in each antimicrobial agent, incidence of multiply resistant strains and correlations in the antimicrobial susceptibility of 58 strains of Enterococci among 14 antimicrobial agents were analyzed. 1. With Tetracycline, Oxytetracline, Doxycycline, Minocycline and Erythromycin, the mean MIC's of Enterococci isolated at Seoul National University Hospital were 1.9-2.5 times higher than those of Enterococci isolated at doctorless areas, though there were no statistical significance. 2. Frequency of resistant strains in Enterococci isolated at Seoul National University Hospital was the highest with Cephalexin(100%), Gentamicin(100%), and Streptomycin(100%), followed by Kanamycin(93.3%), Carbenicillin(90%), Tetracycline(26.7%), Oxytetracycline(26.7%), Doxycycline(26.7%), Minocycline(20%), Erythromycin(10%), Troleandomycin(10%), Penicillin(6.7%), Cotrimoxazole(6.7%) and Ampicillin(0%). 3. Frequency of resistant strains in Enterococci isolated at doctorless areas was the highest with Kanamycin(100%) and Streptomycin(100%), followed by Cephalexin(96.4%), Gentamicin(96.4%), Carbenicillin(92.9%), Tetracycline(10.7%), Oxytetracycline(10.7%), Doxycycline(10.7%), Minocycline(10.7%), Cotrimoxazole(10.7%), Penicillin(3.6%), Ampicillin(0%), Erythromycin(0%), and Troeandomycin(0%). 4. In study with Penicillin, Ampicillin, Tetracycline, Cotrimoxazole, Erythromycin and Troleandomycin, there were no multiply resistant strains in Enterococci isolated at doctorless areas, while 4 strains of Enterococci isolated at Seoul National University Hospital showed multiple resistance. 5. There were high correlation in susceptibility of 58 strains of Enterococci among Tetracycline, Oxytetracycline, Doxycycline and Minocycline(correlation coefficients 0.86-0.97). Correlation coefficients of susceptibility among penicillin analogues(Penicillin, Ampicillin, Carbenicillin and Cephalexin) ranged between 0.75-0.89. Correlation coefficients of susceptibility among aminoglycosides(Kanamycin, Gentamicin and Streptomycin) ranged between 0.09-0.51.