• Journal of Sericultural and Entomological Science
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• v.33 no.2
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• pp.75-81
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• 1991

The study has been carried out to acquire some basic informations about Bacillus thuringiensis for developing the microbial pesticide. Pathogenicity tests on three of B.thuringiensis var. aizawai, kurstaki, and dendrolimus were determined in two species of insects, H. cunea and B. moris. The pathogencity in varieties of B. thuringiensis against H. cunea and B. mori was depended on instar age of tested larvae. Bacillus thuringiensis var. dendrolimus, kurstaki, aizawai are arranged in order of pathogenicity against H. cunea and B. mori. In result Bacillus thuringiensis var. kurstaki was shown the most stable toxicity with respect to each instar of tested larvae.

• Journal of Sericultural and Entomological Science
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• v.34 no.1
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• pp.41-48
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• 1992

Dissolution and degradation of the parasporal crystal proteins produced from B. thuringiensis var. kurstaki, B. thuringiensis var. dendrolimus and B. thuringiensis var. aizawai were investigated. SDS-polyacrylamide gel electrophoresis analysis showed that the crystals contained major protein with molecular weight of approximately 134 kDa for B. thuringiensis var. aizawai 143 kDa for B. thuringiensis var. kurstaki and 149 kDa for B. thuringiensis var. dendrolimus, respectively. Crystals of three other strains were incubated alkali solutions at various pH or gut juice of Silkwarm Bombyx mori, Fall webworm Hyphantria cunea, and Common Cabbage worm Pieris rapae. When crystals of these strains were solubilized by alkali solutions, no major differences among strains B. thuringiensis could be detected. Among the strains studied, crystal protins (130-66 kDa) consist of protease resistant polypeptides in the 45-66 kDa size range when treated with gut juice of three insect species.

• The Journal of Natural Sciences
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• v.6 no.1
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• pp.41-48
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• 1993

A cloned delta-endotoxin gene from Bacillus thuringiensis var. kurstaki NRD 6 was mutated at N-terminal toxic portion of the protoxin by site-directed mutagenesis. A Stu 1 restriction site was created in protoxin region of the mutant B.t.kurstaki NRD 6-Stu 1 which changed A to C in 177 region of the protoxin(silent mutation). Antigenic property of crystalline inclusion (delta-endotoxin) of the mutant was no difference to intact strain by the western blot analysis and its toxidity threshold value was also showed 0.015~0.030ng against Choristoneura femiferana-1 insect, similar with 0.01~0.024ng of parent strain, but stronger than that of B.t.kurstaki NRD 5 (500~1000ng) and B.t.kurstaki NRD 4(none toxic).

• Journal of Sericultural and Entomological Science
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• v.37 no.1
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• pp.62-67
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• 1995

Ultrastructural changes of tissues caused by Bacillus thuringiensis var. kurstaki $\delta$-endotoxin intoxication of Hyphantria cunea were observed by transmission electron microscopy. Bt $\delta$-endotoxin crystals induced the disruption of microvilli, vacuolation of cytoplasm, changes in the cisternae of the endoplasmic reticulum, disappearance of basal striations, loss of ribosomes, and changes in the configurations of mitochondria in the columnar cell of midgut. The fat body cells also showed spherical endoplasmic reticulum and distorted mitochondria, and then the cells were destroyed.

• Journal of Sericultural and Entomological Science
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• v.37 no.1
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• pp.68-73
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• 1995

The toxic effect of Bacillus thuringiensis var, kurstaki $\delta$-endotoxin was determined in the midgut, fat body and Malpighian lobules from larvae of Hyphantria cunea using the au-toradiography and Western blot methods. Bt $\delta$-endotoxin crystals inhibited protein synthesis and elongation factor-2 activity of all tissues tested.

• BMB Reports
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• v.34 no.2
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• pp.130-133
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• 2001

The amino acid sequences of 130 kDa and 72 kDa proteins responsible for the larvicidal activity of Bacillus thuringiensis var israelensis (Bti) were analyzed by hydrophobic moment plots. A search for highly amphiphilic $\alpha$-helices was made in these proteins using the helical hydrophobic moment as a criterion of amphiphilicity The protein segments of the largest hydrophobic moments were analyzed. In the present communication we report the surface seeking helices in 130 kDa and 72 kDa proteins of Bacillus thuringiensis var israelensis. It is assumed that the surface seeking segments may participate in one of the membrane-related functions of Bacillus thuringiensis.

• The Korean Journal of Ecology
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• v.22 no.1
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• pp.51-58
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• 1999

Korean native plants and naturalized plants were analyzed for allelochemicals, and their antimicrobial effects were studied. The difference in soluble solid contents between Korean native plants and naturalized species was not significant, and the Korean native plant, Solanum nigrum showed the highest soluble solid content of 90 mg/ml. The ethanol extract of the Korean native plant, Solanum nigrum showed antifungal activity to Aspergillus phoenicis KCTC 1228, with a clear zone of 18 mm, and spore formation was not observed from the treatment. The naturalized plants Ambrosia artemisiifolia var. elatior and Erigeron canadensis showed inhibition of spore formation and the clear zones were at 24 mm and 22 mm, respectively. The clear zones of Aspergillus phoenicis KCTC 1228 treated with ethanol extrats of Phytolacca americana and Rudbeckia bicolor were 22 mm and 19 mm, respectively, and spore formation was observed from the treatment. The Korean native plant, Solanum nigrum and naturalized plants, Phytolacca americana and Ambrosia artemisiifolia var. elatior showed antimicrobial activity against Bacillus sphiaericus 2362, and Bacillus sphiaericus 2297, Bacillus thuringiensis var. subtilis and Baicillus thuringiensis var. cereus. The antimicrobial activity of Ambrosia artemisiifolia var. elatior showed the largest clear zone of 32 mm against Bacillus thuringiensis var. subtilis. In general, the more soluble the solid contents of the extracts, the greater were the antifungal and antimicrobial activities. The phenolic compounds from the Korean native plant, Solanum nigrum and the naturalized species, Phytolacca americana and Ambrosia artemisiifolia var. elatior were analyzed by high performance liquid chromatography. Three phenolic compounds including hydroquinone were identified in Solanum nigrum. In contrast, five and seven phenolic compounds were identified in Phytolacca americana and Ambrosia artemisiifolia var. elatior, respectively. The antifungal activity against Aspergillus phoenicis KCTC 1228 was found to be due to the coumaric and benzoic compounds.

• Korean Journal of Microbiology
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• v.23 no.4
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• pp.271-281
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• 1985

Bacillus thuringiensis var. thuringiensis produces an extracellular insecticidal thermostable .betha.-exotoxin, which was purified through microfiltering, barium precipitation, charcoal absorption chromatography, ion exchange column chromatography and gel filtration. The exotoxin in each purification step was detedted by thin layer chromatography, high pressure liquid chromatography and paper electrophoresis with efficient results. The exotoxin productivity on time course was checked by spectrophotometric absorbance at 258nm with the result that the exotoxin was initially produced in 6 hour culture and reached maximum value in 36 hour culture. Anti-bacterial effect test on Micrococcus flava was applied as toxicity test. The results showed that frowth inhibition of M. flava could be shown in plate assay of cell free filtered supernatant, alkaline eluant from charcoal and purified exotosin obtained from gel filtration column chromatography on Sephadex G-10 appeared to be 740. Heat stability of the exotoxin was confirmed through autoclaving twice.

• The Korean Journal of Ecology
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• v.23 no.5
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• pp.353-357
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• 2000

The soil pH favored by several native plants in Korea ranges 5.33∼7.20, while a more acidic range of pH 3.95∼6.10 is acceptable to exotic plants. Ethanol extracts of native and exotic plants in Korea were investigated for antimicrobial activity against Bacillus sphiaericus 2362, Bacillus thuringiensis var. subtilis and Bacillus thuringiensis var. cereus and Actinomycetes. Higher antimicrobial activity was observed from the extract of exotic plants than those of native plants. The ethanol extract of Ambrosia artemisiifolia var. elatior was observed to have the highest antimicrobial activity against 4 species of soil microbes. Especially, antimicrobial activity of Ambrosia artemisiifolia var. elatior showed the largest clear zone of 48mm in Actinomycetes. Larger clear zone was formed in the order of caffeic acid, benzoic acid and ρ -coumaric acid among the nine chemical compounds. Accordingly, the antimicrobial activity of Ambrosia artemisiifolia var elatior against Actinomycetes was found to be due to the synergetic effect of chemical compounds.

• Applied Microscopy
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• v.12 no.1
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• pp.33-40
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• 1982

Several phages of Bacillus thuringiensis distributed in Korea were isolated. The distribution and morphological characteristics of phages were studied. The results are as follows; 1. The isolated phages were highly specific for Bacillus thuringiensis var. thuringiensis. They were classified as YM series phages and designated as phage YM-1, YM-2 and YM-3 according to their morphological characteristics. 2. Most of these YM series phages were isolated from compost including domestic animal dung and soil under sewage. 3. The YM-1 phage was similar to Bacillus subtilis ${\phi}25$ in morphology. It has 94nm x 86nm head, contractile tail sheath and base plate with four cornered structure. 4. The YM-2 phage was similar to Bacillus subtilis GA-1 phage in morphology. It had 70nm x 56nm head and tail without contractile tail sheath. 5. The YM-3 phage was similar to Bacillus subtilis ${\phi}29$ phage. It had 56nm x 43nm head and tail with distal enlargement.