• Microbiology and Biotechnology Letters
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• v.25 no.6
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• pp.566-570
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• 1997

During sporulation, Bacillus thuringiensis strains produce crystals consist of toxin proteins highly specific against insect pests. Their host specificities are desirable from a standpoint of environmental safety, but also limit market potential. Thus, development of improved Bacillus thuringiensis strains having broad host spectrum will contribute to increase its use. For the construction of Bacillus thuringiensis strain having broad host spectrum, we cloned cry1C gene encoding a toxin protein highly toxic against Spodoptera exigua from a B. thuringiensis isolate and constructed two recombinant plasmids, pUBClC and plC60. The plasmid PUBC1C has a replication origin of the natural plasmid pBC16 from B. cereus which is closely related species to B. thuringiensis, and the pBC16 was known to be replicated by rolling-circle mechanism. The plasmid pIC60 has a replication origin of a resident 60 MDa plasmid from B. thuringiensis subsp. kurstaki HD263, and it is believed that the pIC60 is replicated in a theta mode. The two plasmids were introduced into B. thuringiensis subsp. kurstaki cryB strain, and the transformed strains produced well-shaped bipyramidal crystals. We confirmed the expression of the cry1C gene by SDS-PAGE, and Western blotting. By investigating the segregational stability, it was found that the plasmid pIC60 is more stable than the pUBC1C.

• Journal of Microbiology and Biotechnology
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• v.9 no.5
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• pp.534-540
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• 1999

Thirty-seven strains of Bacillus thuringiensis were isolated from Korean soil and examined for H-antigen serotyping, toxicity, and different spectra of biological activities. The isolate HL-175 bore a specific H-antigen, different from the 51 known serotypes, a spherical $\delta$-endotoxin crystal, and minor different biochemical characteristics. It was resistant to ampicillin, colistin, and penicillin G. Therefore, it was classified as a new serotype, H52, with the name kim. The other 36 isolates also produced endotoxin crystals and endospores. The crystal shape of eight strains was cuboidal while the others were bipyramidal. Biochemical characteristics of the isolates were only slightly different from the known serotypes of B. thuringiensis. The flagellar (H) antigens of the 36 isolates were identified as: one colmeri (H21), three galleriae (H5a,5b); two pakistani (H13); one toumanoffi (H11a, 11b); and twenty-nine kurstaki (H3a,3b). All 36 isolates were resistant to ampicillin, colistin, penicillin, cephalothin, and chloramphenicol.

• Microbiology and Biotechnology Letters
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• v.18 no.3
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• pp.301-304
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• 1990

In the mosquitocidal delta-endotoxins from Bacillus thuringiensis subsp, isruelensis and B. thuringiensis subsp. darmstudiensis 73E10-2, were contained an immunologically homologous protein. The homologous protein was confirmed from Ouchterlony test, irnmuno-electrophoresis, and enzyme linked immunoassay by polyclonal antibodies against the delta-endotoxins of both strains.

• Microbiology and Biotechnology Letters
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• v.14 no.4
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• pp.329-334
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• 1986

Bacillus thuringiensis serovar israelensis H 14 strain was cultured in 4 different fermentation M-media and then measured the rates of their growths and the productions of endotoxin crystals front the media. Out of the four M-media the production of endotoxin crystals and spores was maximal in M-4 medium (pH 9). The wet weight of the cells grown in the 150$m{\ell}$ culture was approximately 3.901g and the number of viable spores was 1.53$\times$10$^{12}$ per nil and the ratio of the endotoxin over the total cell weight was 18.54%. The generation time was about 89.3 minutes in the M-1 medium, 124.1 minutes in the M-2, 97 minutes in the M-3, 130.8 minutes in the M-4. The proper pHs for the production of the endotoxin appeared to be 6.5 to 7.5.

• Korean Journal of Organic Agriculture
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• v.19 no.spc
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• pp.259-262
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• 2011

In organic Chinese cabbage fields, Commercial Bacillus thuringiensis products are used widely against diamond back moth, Plutella xylostella. We conducted the study to determine the effective spray-interval of commercialized B. thuringiensis against diamond back moth on Chinese cabbages. Chinese cabbage leaves were collected 0, 1, 2, 3, 6, 10days after treatment in first trial and 0, 2, 4, 7, 9, 11days after treatment. We compared the insecticidal property of sprayed B. thuringiensis and the density of it on surface of Chinese cabbages using collected leaves. The insecticidal property maintained high until nine days after commercial B. thuringiensis products sprayed.

• Journal of Microbiology
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• v.45 no.6
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• pp.553-557
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• 2007

In order to detect and identify the most toxic Bacillus thuringiensis strains against pests, we isolated a B. thuringiensis strain (Bn1) from Balaninus nucum (Coleoptera: Curculionidae), the most damaging hazelnut pest. Bn1 was characterized via morphological, biochemical, and molecular techniques. The isolate was serotyped, and the results showed that Bn1 was the B. thuringiensis serovar, kurstaki (H3abc). The scanning electron microscopy indicated that Bn1 has crystals with cubic and bipyramidal shapes. The Polymerase Chain Reactions (PCRs) revealed the presence of the cry1 and cry2 genes. The presence of Cry1 and Cry2 proteins in the Bn1 isolate was confirmed via SDS-PAGE, at approximately 130 kDa and 65 kDa, respectively. The bioassays conducted to determine the insecticidal activity of the Bn1 isolate were conducted with four distinct insects, using spore-crystal mixtures. We noted that Bn1 has higher toxicity as compared with the standard B. thuringiensis subsp. kurstaki (HD-1). The highest observed mortality was 90% against Malacosoma neustria and Lymantria dispar larvae. Our results show that the B. thuringiensis isolate (Bn1) may prove valuable as a significant microbial control agent against lepidopteran pests.

• Journal of Microbiology and Biotechnology
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• v.23 no.1
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• pp.88-91
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• 2013

The Cyt1Aa protein of Bacillus thuringiensis subsp. israelensis is known to synergize mosquitocidal proteins of B. thuringiensis and Bacillus sphaericus strains. Cyt1Aa is highly lipophilic, and after binding in vivo to the midgut microvillar membrane serves as a "receptor" for mosquitocidal Cry proteins, which subsequently form cation channels that kill mosquito larvae. Here we report that Cyt1Aa can serve a similar function for lepidopteran-specific Cry proteins of B. thuringiensis in certain mosquito larvae. Engineering Cyt1Aa into the HD-1 isolate of B. thuringiensis subsp. kurstaki enhanced toxicity against $4^{th}$ instars of Aedes aegypti, but not against $4^{th}$ instars of Culex quinquefasciatus.

• International Journal of Industrial Entomology and Biomaterials
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• v.8 no.1
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• pp.89-93
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• 2004

Expression of a fusion protein between B. thuringiensis crystal protein, Cry1Ac1 and a scorpion insect toxin (AaIT, Androctonus australis Hector insect toxin) in acrystalliferous B. thuringiensis strain (Cry-B strain) was examined. The cry 1Ac1 gene was cloned in B. thuringiensis-E coli shuttle vector, pHT3101, under the control of the native cry 1Ac1 gene promoter (pProAc) and a gene encoding AaIT was inserted in XhoI site in the middle of the cry 1Ac1 gene (pProAc-ScoR). B. thuringiensis Cry-B strain carrying pProAc-ScoR (PyoAc-ScoR/CB) produced an inclusion body of irregular shape and the expressed fusion protein is approximately 65 kDa in size. Sporulated cells and spore-crystal mixtures of ProAc-ScoR/CB had insecticidal activity against Plutella xylostella larvae, showing $LT_50$ of ProAc-ScoR/CB (22.59 hrs) lower than that of ProAc/CB (30.06 hrs) at $1{\times}{10^7} {CEU/cm^2}$. These results suggest that the fusion protein including a B. thuringiensis crystal protein and an AaIT may be functionally expressed in B. thupingiensis. Moreover, we verified the additive toxicity of AaIT, which is a new feasible candidate for insect control.

• Korean Journal of Food Science and Technology
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• v.52 no.6
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• pp.678-684
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• 2020

The objective of this study was to identify the fermentation characteristics of Bacillus thuringiensis and emetic, non-emetic Bacillus cereus using analytical profile index (API) test. Ten strains of B. thuringiensis and 10 strains of B. cereus including 3 strains of emetic type were used at the same concentrations. The differences of fermentation characteristics between the B. thuringiensis and B. cereus was not obvious, but the differences between the non-emetic and emetic B. cereus were distinctive. Seven among 50 substrates were negative for all non-emetic B. cereus strains and positive for all emetic strains, and three substrates among additional 12 substrates had the same tendency. From these differences, 3 emetic B. cereus strains were not indicated as B. cereus by API test. These results indicate that API test is not a suitable method to identify some strains of emetic B. cereus, and the distinctive differences in substrate utilization can be used to improve selective media.

• 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.