• Microbiology and Biotechnology Letters
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• v.14 no.3
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• pp.259-264
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• 1986

The compositions of the four madia and their pHs for delta endotoxin production by B. thuringiensis serovar kurstaki 3a3b were examined. In the M-4 media out of the 4 media at pH8, the production of the endotoxin and spore formation were maximal. The mean generation times of the bacterium were 53.4 minutes in the M-1 media, 98 in the M-2, 132 in the M-3, and 127.5 in the M-4. The proper pHs of the media for the endotoxin production appeared to be pH 7 to 8. In the M-4 media, the lag time lasted about 5 hours.

• Microbiology and Biotechnology Letters
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• v.18 no.6
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• pp.647-652
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• 1990

The production of delta-endotoxin crystal and the cloning of endotoxin protein gene in Bscillus thuringiensis subsp. kurstaki HD1 strain were studied. The strain produced bipyramidal crystals ($2.9\times 1.0 \mu m$) in their cells during sporulation. The B. thuringiensis contained about 10 plasmid DNA elements ranging from 2.1 to 80 kilobases. The 73 kb plasmid DNA, the 29 kb BamHI fragment and the 7.9 kb Pstl DNA fragment hybridized to the pHL probe. The 7.9 kb fragment was eluted and cloned in the PstI site of pBR322 vector and transformed into E. coli HB101, which produced insecticidal proteins killing Bornbyx mori larvae.

• Microbiology and Biotechnology Letters
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• v.23 no.6
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• pp.730-736
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• 1995

The solubilization and proteolytic process of $\delta $-endotoxin was analvsed to compare the biochemical property of the toxin isolated from B. thuringiensis subsp. sotto. The purified crystals were dissolved in 50 mM carbonate buffer containing 10 mM dithiothreitol at pH 10 for various times. The electrophoretic pattern showed that a rapid disappearance of 138 kDa protein band. This disappearance of protein with high molecular weight was accompanied by the appearance of new protein fragment with 104 kDa, 60 kDa, and 25 kDa. For proteolvtic processing, the soluble crystals were digested with trypsin for various times. The soluble crystal protein of 104 kDa was completely disappeared. However, the protein fragment of 60 kDa and 25 kDa still remained after complete proteolysis. The comparative immunoblot analysis showed that the antiserum against intact crystals showed strong immunoreactivity to the homologous inclusion protein of 138 kDa, 104 kDa, and 25 kDa, and to the intact spores of 221 kDa and 138 kDa, but not to the vegetative cell homogenate. The sera against crystals and spores had no immunoreactivity to the vegetative cell homogenate.

• Journal of Sericultural and Entomological Science
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• v.35 no.2
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• pp.120-128
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• 1993

The objective of this study is to identify plasmids of Bacillus thuringiensis var. kurstaki HD-1(B. t k HD-1) toxic to lepidopteran larvae. The results from agarose gel electrophoresis indicated that the bacterium contained 9 plasmids with approximate sizes of 1.4, 4.9, 5.4, 9.3, 10, 29, 44, 52, and 150 megadaltons(Md). By treating the wild type of B. t k HD-1 with either SDS or EtBr as curing agent, 26 cured mutants of the bacterium were obtained, 9 of them were crystallifereous(cry+) and the others acrystallifereous(cry-). Plasmids from B. t k HD-1 were transferred to B. cereus 569 strR cry- recipients(Bc569 M1). Among 13 isolates of Bc569 M1 transcipient, 11 of them were capable of producing the crystal toxic proteins. The plasmid patterns of Bc569 M1 transcipients and partially curved mutants of B. t k HD-1 on agarose gel electrophoresis suggested that the 29 and 44Md plasmids should be involved in the production of crystalline toxic proteins.

• Microbiology and Biotechnology Letters
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• v.26 no.4
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• pp.358-364
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• 1998

New microbial-control agents were prepared with B. thuringiensis strain NT0423 having unique properties which are different with other B. thuringiensis strains belonging to serotype 7[Kor. J. Appl. Entomol. 32: 426-432.]. Three B. thuringiensis formulations designated as BioBact 10%, 20% and 40%, were made with various combinations of adjuvants. These formulations showed good physical properties in wettability, suspensibility, particle size and adherence. In addition the result of SDS-PAGE analysis indicated that $\delta$-endotoxins remain stably in all formulations. Among the tested formulations, two wettable powder formulations, BioBact 20% and 40%, comprising 20% and 40% of B. thuringiensis technical powder showed the effective control against diamondback moth larvae (Plutella xylostella) in laboratory and field tests. Especially, when compared with commercial B. thuringiensis formulations (A and B commercial formulations) in field evaluation, BioBact 20% and 40% formulations showed equal activity up to 80% lethality and a good persistence effect which remain on leaves at least 7 days.

• Microbiology and Biotechnology Letters
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• v.35 no.3
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• pp.250-254
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• 2007

Bacillus thringiensis strain 108 was isolated from soil and had nematicidal activity against second stage juvenile of plant root-knot nematode, Meloidogyne incognita. The strain 108, a rod shape, spore forming and Gram positive bacterium, produced lecithinase, catalase, and ${\delta}$-endotoxin. The strain 108 belongs to H serotype 3, Bacillus thuringiensis var. kurstaki. A nematicidal substance of the strain 108 was partially purified on Sephadex G-25 gel filtration, activated carbon adsorption, silica gel adsorption, and Sephadex G-10 gel filtration. $LC_{90}$ of the partially purified substance against M incognita was $1.2\;{\mu}g/ml$. The nematicidal substance was stable by heat treatment at $100^{\circ}C$ for 1hr, but was perfectly lost nematicidal activity after autoclave ($110^{\circ}C$, 30 min).