• Korean Journal of Microbiology
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• v.23 no.3
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• pp.203-208
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• 1985

Partial characterization of B. thuringiensis var. kurstaki 3ab temperature-sensitive mutants was carried out through biochemical analyses, utilization tests of carbohydrate sources, antobiotic resistant test, hemolytic reaction test, growth measurement of Fructus gardenia sxtrant medium and toxicity test against mice. Six ts mutants, ts-U154, ts-U601, ts-U602, ts-U603, tsU-604, and ts-U788 could not produce urease, ts-U603 lost its motility, ts-U154 could not use salicin and cellobiose and ts-U603 not ribose. All ts mutants except ts-U154 and wild type strain were resistant to cephalothin, ampicillin, and penicillin. but ts-U154 was sensitive to the three. Four mutants, ts-U21, ts-U74, ts0U131 and ts-U154 did not form pigment colonies on the F. gardenia medium. All the mutants and wild type strain showed hemolysis reaction on the blood agar. The B. thuringiensis and mutants were not toxic to mice.

• Journal of Sericultural and Entomological Science
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• v.28 no.1
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• pp.43-53
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• 1986

Among many microbial pesticides, Bacillus thuringiensis is one of the most hopeful pesticide and some commercial products have been appearing on the market. Because these commercial products contain living spores and toxins of the organism, there is a danger that living spores of B. thuringiensis may be scattered by wind and cause a great damage in the sericulture areas. In order to avoide these risks it is desirable to select the strain which has low pathogenicity to the silkworm, and at the sometime being highly pathogenic to the pest insects. Thus this study has been carried out to acquire some basic informations about the procedure of desicable strain selection. Three strains of B. thuringiensis var. kurstaki, var. dendrolimus and var. aizawai were used for the pathogenicity test on the silkworm, Bombux mori and the fall webwarm, Hyphantria cunea. Those strains were investigated by the agarose gel electrophoresis patterns of plasmid DNA determine whether mutation had occured. Pathogenicity tests were carried out of using isolated crystal proteins and spore-crystal protein to mixtures of each strain, seperatively. In case of using spore-crystal protein mixture, the order of pathogenicity in varities of B. thuringiensis against B.mopri and H.cunea were kurstaki, aizawai, dendrolimus and kurstaki, dendrolimus, aizawai, respectively. But using isolated crystal proteins, dendrolimus had the highest toxicity to H. cunea and the lowest toxicity to B. mori among tested three strains. From the above results, dendrolimus was presumed the most desirable straing for using microbial pesticide.

• Journal of Sericultural and Entomological Science
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• v.33 no.1
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• pp.32-36
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• 1991

The study has been carried out to acquire some basic informations about Bacillus thuringiensis for developing the microbial pesticide. Three strains of Bacillus thuringiensis var. Kurstaki, dendrolimus and aizawai, were used in the experiments as follows. Growth characteristics of each strain were examined and parasporal protein crystals were isolated from the mixtures of spores and protein crystals by the new method of centrifugation in two-layer cushion of Renograffin using a fixed angle rotor. The results are as follows. 1. No difference was shown in growth characterestics among three strains of B. thuringiensis. In growth curves, all strains reached to exponential phase by 2 hr and stationary phase by 7-8 hr after inoculation. 2. The pH of the culture media during exponential growth stage decreased about 1.4 of a pH unit at the beginning of sporulation, but recovered during the early stage of sporulation and then remained nearly constant during the later stage. 3. As 10$m\ell$ sample was applied to two-layer cushion of Renograffin and then centrifuged for 1hr at 27,000g a fixed angle rotor, the purity and recovery ratio was 99.9% and 5.8%, respectively. It has been shown that the new method for the isolation of parasporal protein crystals was more efficient than any from the estabilished methods.

• Proceedings of the Korean Society of Applied Entomolohy Conference
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• 2002.05a
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• pp.189-189
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• 2002

• Proceedings of the Korean Society of Applied Entomolohy Conference
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• 2002.11a
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• pp.151-151
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• 2002

• Microbiology and Biotechnology Letters
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• v.16 no.5
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• pp.348-351
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• 1988

The production of extracellular $\alpha$-amylase by Bacillus thuringiensis 19 serotypes was examined by the hydrolysis test of starch. Thirteen serotypes produced the amylase. B. thuringiensis serovar thuringiensis alesti, kurstaki, sotto, kenya, israelensis, morrisoni, entomocidus, tolworthi, thompsoni, toumanoffi, pakistani, and indiana produced tee enzyme. The amylase produced by B. thuringiensis serovar israelensis showed highest activity around pH 6.7 to 7.2 and 55$^{\circ}C$ to $65^{\circ}C$. The high production medium of the amylase was composed of 1% bactopeptone, 0.3% beef-extract, 0.3% yeast ex-tract, 0.5% NaCl, 0.3% $K_2$HPO$_4$, 0.1% KH$_2$PO$_4$, 0.2% Soluble Starch, 0.012% CaCl$_2$.2$H_2O$$_2$, 0.005% MnCl$_2$, and 0.03% MgCl$_2$.7$H_2O$. The highest production of the enzyme was observed at 4 hours culture in the soluble starch (0.6 units/$m\ell$) or glucose (0.43 units/$m\ell$) substrate.

• Proceedings of the Korean Society of Applied Entomolohy Conference
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• 2002.11a
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• pp.152-152
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• 2002

• Animal cells and systems
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• v.1 no.3
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• pp.507-513
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• 1997

Sequential observations of binding patterns and structural effects of Bacillus thuringiensis var. kurstaki were made on fat body tissue of the fall webworm, Hyphantria cunea Drury. Fat body was cultured in vitro in the presence of purified 62 kDa endotoxin and then examined for protein synthesis and the localization of membrane-bound toxin detected by an antibody against the 62 kDa endotoxin. Protein synthesis was mostly inhibited at concentrations of 15 ${\mu}$g/ml and higher. Immunocytochemical observations suggest that the toxin binds to all exposed basal lamina surrounding the fat body without apparent specificity. The cytopathic effect delectable by scanning electron microscope is disintegration rather than cell swelling. The basal lamina bound toxin was eventually detached from the fat body and followed by an extrusion of cell contents like lipid granules.

• Korean Journal of Plant Tissue Culture
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• v.24 no.5
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• pp.305-311
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• 1997

Bacillus thuringiensis, a gram-positive soil bacterium, is characterized by its ability to produce crystalline inclusions during sporulation. The crystal proteins exhibit a highly specific insecticidal activity. An insecticidal crystal protein (ICP), Cry II A, is specifically toxic to both lepidopteran and dipteran insects. In this study, tobacco plants transformed by the cry II A gene have been generated. The Cry II A crystal protein was purified from E. coli JM103 harboring cry II A gene by differential solubility. The activated Cry II A was prepared by tryptic digestion. The purified protoxin (70 kDa) and the activated toxin (50 kDa) were analyzed by SDS-PAGE. To generate the transgenic tobacco having cry II A gene, the cry II A gene was subcloned to a plant expression vector, pSRL2, having two CaMV 35S promoters. The recombinant plasmid was transformed into tobacco (N. tabacum var. Petit Havana SR1) by Agrobacterium-mediated leaf disc transformation. Through the regeneration, six putative transgenic tobacco plants were obtained and three transformants were confirmed by Southern blot analysis. It has been found that one plant had single copy of cry II A gene, another had two copies of the gene, and the third had a truncated gene. After the immunochemical confirmation of cry II A expression in plants, the transgenic tobacco plants will be used to study the genetics of future generation with the insecticidal crystal protein gene cry II A.

• KSBB Journal
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• v.13 no.6
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• pp.644-648
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• 1998

In the production of a low cost bacterial insecticide, it is important to produce a high spore concentration using low price substrates. Experiments were carried out to investigate the effects of the addition of mineral salts and glucose, and of dissolved oxygen concentration on the cell growth and spore formation of Bacillus thuringiensis var aizawai using a cheap wheat and soybean meal in the batch culture. The maximum viable cell number was 1.2${\times}$109 CFU/mL at 12 hr culture and spore yield was 54.2% at 74 hr culture using an industrial medium containing 20 g/L wheat meal and 30 g/L soybean meal under 1.0 vvm aeration and 200 rpm agitation. The cell growth and the spore formation were not enhanced by the addition of mineral salts in industrial medium, whereas th addition of 10g/L glucose decreased the cell growth and spore formation. We could obtain a maximum viable cell number of 2.2${\times}$109 CFU/mL and spore number of 1.9${\times}$109 CFU/mL at the dissolved oxygen concentration of 60% of saturation. The spore concentration was enhanced approximately by 2 times as compared to the dissolved oxygen concentration of 50%. In the bench-scale culture, the maximum viable cell and spore number were 2.5${\times}$109 CFU/mL, and 2.2${\times}$109 CFU/mL, respectively under 1.0 vvm aeration and 400 rpm agitation. The spore yield was 88% based on the maximum viable cell number. As a result, it was confirmed that the production of high spore concentration could be obtained by a bench-scale culture using an industrial medium.