• Journal of Microbiology and Biotechnology
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• v.4 no.3
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• pp.171-175
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• 1994

To find new crystal protein genes, we screened 42 Bacillus thuringiensis strains of serovar standards by Southern hybridization with a cryI-specific probe which was amplified from B. thuringiensis subsp. kurstaki HDl by polymerase chain reaction (PCR). Two strains, B. thuringiensis subsp. entomocidus HD9 and subsp. subtoxicus HD109, generated weak signals under the low-stringency hybridization conditions. Further analysis with Southern hybridization revealed that the two strains contained cryIB genes which are slightly different from those of B. thuringiensis subsp. thuringiensis HD2. These results were confirmed by PCR with cryIB-specific primers followed by the restriction analysis of PCR products.

• Proceedings of the Korean Society of Sericultural Science Conference
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• 2003.04a
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• pp.31-32
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• 2003

Bacillus thuringiensis produces insecticidal parasporal inclusions (crystal protein) used as a major ingredient of most microbial insecticides. Although many B. thuringiensis strains and their crystal proteins have been isolated and characterized, such findings have limitation of usefulness. For enhanced toxicity, fast effects, and the delay of resistance development, research on genetic manipulation of crystal genes and proteins by genetic engineering should be continued. (omitted)

• Microbiology and Biotechnology Letters
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• v.33 no.2
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• pp.154-158
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• 2005

Twenty-three Bacillus thuringiensis strains isolated from Korea were screened to detect the cry-type genes using PCR with 21 specific oligonucleotide primers. Eight strains contained distinct multiple crystal genes; cry1Aa2, cry1Ab1, cry1Ac1 and cry2Aa1. These results indicate that the strains coincided with the B. thuringiensis subsp. kurstaki strain. The other 15 strains were not recognised to the 21 specific primers.

• Proceedings of the Zoological Society Korea Conference
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• 1994.10a
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• pp.264-264
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• 1994

• Korean journal of applied entomology
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• v.48 no.4
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• pp.519-526
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• 2009

Bacillus thuringiensis subsp. kurstaki KB100 isolated from the domestic soil have the most effective activity against the beet armyworm, Spodoptera exigua larva. The tannic acid as protease inhibitor might be increased the efficacy of sublethal concentrations of B. thuringiensis. The tannic acid was identified as a protease inhibitor that could increased the efficacy of sublethal concentrations of B. thuringiensis. Mixture of B. thuringiensis and tannic acid was investigated the mortality of S. exigua larva in the laboratory and field. When B. thuringiensis treated to 2nd larva of S. exigua, mortality was shown 54.4%. However, mixtures of B. thuringiensis with 4 and 40 mM tannic acid were increased mortalities to 2nd larva of S. exigua as 64.0 and 95.5%, respectively. Also, synergy effect of mixture of B. thuringiensis and 40 mM tannic acid was increased the mortality of S. exigua 3rd larva to 93.3%, even though 60.0% mortality with only B. thuringiensis treatment. On the other hand, the mortality of mixture with B. thuringiensis and 80 mM tannic acid was 53.3% lower than B. thuringiensis single treatment. In the welsh onion field, the accumulated mortalities of 3 times replicated with mixture of B. thuringiensis and 40 mM tannic acid were 83.9, 89.4 and 66.8% compare with 61.8, 80.4 and 47.3% as only B. thuringiensis treatment, respectively.

• International Journal of Industrial Entomology and Biomaterials
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• v.1 no.2
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• pp.123-129
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• 2000

Expression of the crylAcl gene of an acrystalliferous Bacillus thuringiensis strain under the control of the native or $\alpha$-amylase gene promoter was investigated. The crylAcl gene was cloned in a B. thuringiensis - E. coli shutle vector, pHT3101, undder the control of either the native promoter (pProAc) or the $\alpha$-amylase promoter from Bacillus subtilis (pAmyAc). These two recombinant plasmids were successfully expressed in B. thuringiensis subsp. kurstaki Cry B. The first transformant (ProAc/CB), harboring pProAc, expressed an about 130 kDa protein begining 24 hr after inoculations just as in the case of the wild type of B. thuringiensis subsp. kurstaki HD-73. The second pAmyAc-transformant (AmyAc/CB) began to express the gene just 6 hr after inoculation, but Western analysis showed that the activity of the $\alpha$-amylase promoter was relatively weaker than that of the native promoter. As expected, their toxicity against Plutella xylostella larvae was dependent on the amount of Cry1Acl protein expressed.

• The Korean Journal of Pesticide Science
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• v.11 no.3
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• pp.201-209
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• 2007

Characteristics of the 5 biopesticides that included Bacillus thuringiensis and on the domestic markets were investigated. These products were contained different strains of B. thuringiensis, for examples; product A and E was B. thuringiensis subsp aizawai; product B was B. thuringiensis; product C was B. thuringiensis Berline var. kurstaki; product D was B. thuringiensis var. kurstaki. Number of active spores were counted because they could influence the bio-activity against target pests. Only product C are contained the fixed quantity as its label, however, product D and E were a tenth part, and product A and B were a hundredth part of their descriptions. The pHs of product A and B were measured 3.67 and 3.73, and C, D and E were 5, respectively. Typical bypyramidal crystals produced from B. thuringiensis was found in only product C under a phase contrast microscope. For the uniform formulation of products that conformed whether B. thuringiensis were equally spreaded on the crops, B. thuringiensis in the C, D and E were equally grown on the nutrient agar medium As a results, product A were more different from product C than any other products. When product A and C were bioassayed against different larval stages of diamondback moth, their mortalities with spraying application were showed 100% after 48 hours.

• Journal of Microbiology and Biotechnology
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• v.1 no.1
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• pp.37-44
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• 1991

A shuttle promoter-probe vector, pEB203, was derived from pBR322, pPL703 and pUB110. Using the vector, a useful DNA fragment, 319 bp EcoRI fragment, having strong promoter activity has been cloned from Bacillus subtills chromosomal DNA. Selection was based on chloramphenicol resistance which is dependent upon the introduction of DNA fragments allowing expression of a chloramphenicol acetyl transferase gene. The nucleotide sequence of the 319 bp fragment has been determined and the putative -35 and -10 region, ribosome binding site, and ATG initiation codon were observed. This promoter was named EB promoter and the resultant plasmid which can be used as an expression vector was named pEBP313. The crystal protein gene from B. thuringiensis subsp. kurstaki HD-73 was cloned downstream from the EB promoter without its own promoter. When the resultant plasmid, pBT313, was introduced into Escherichia coli and B. subtilis, efficient synthesis of crystal protein was observed in both cells, and the cp gene expression in B. subtilis begins early in the vegetative phase. The cell extracts from both clones were toxic to Hyphantria cunea larvae.

• International Journal of Industrial Entomology and Biomaterials
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• v.3 no.1
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• pp.19-23
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• 2001

Two B. thuringiensis strains, which possess mosquitocidal activities, were isolated from Korean soil samples and named K-1205-1 and K-1381-1. Serological studies indicated that K-1205-1 and K-1381-1 belonged to B. thuringiensis subsp. kurstaki (H3a3b3c) and subsp. aizawai (H7), respectively. K-1205-1 produced typical bipyramidal parasporal inclusions, but K-1381-1 produced irregular bipyramidal shape. Total plasmid DNA patterns analysis shewed that K-1205-1 and K- 1381-1 were different from their reference strains, subsp. kurstaki and subsp. aizawai, respectively, in high molecules, whereas their crystal protein patterns showed no difference. The cry gene contents of K-1205-1 and K-1381-1 were identical with those of the reference strains. Mosquitocidal activities of crystal proteins produced by K-1205-1 and K-1381-1 were significantly high by about 40-50 folds at $LC_50$ when compared to those of subsp. kurstaki and subsp. aizawai. Finally, in southern blot analysis using cry1A-type specific probe, K-1205-1 and K-1381-1 had different bands from subsp. kurstaki and subsp. aizawai, respectively. In conclusion, our results suggest that K-1205-1 and K-1381-1 appear to be new moquitocidal B. thuringiensis strains isolated from Korean soil.

• Applied Biological Chemistry
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• v.39 no.3
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• pp.177-182
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• 1996

Effects of 14 carbohydrates supplied as carbon sources on cell growth and sporulation of, and the production of insecticidal crystal proteins by Bacillus thuringiensis strains were investigated in liquid cultures. Strains grew well in media containing any one of the 14 carbohydrates supplied, reaching maximum cell densities of $10^7{\sim}10^8\;cells/ml$ in 16.7 to 22 hours after inoculation depending on the strain. Spores first appeared in 16.7 to 24.7 hours after inoculation, and 80% sporulation was reached in 28 to 51.3 hours after inoculation depending on the strain. No change in pH of media was observed after cell multiplication. The production of total protein was highest when supplied with sucrose and was lowest with starch. More insecticidal crystal proteins were produced when supplied with glucose, lactose, maltose, or sucrose. The amount of insecticidal crystal proteins produced by the strains was proportional to that of the total protein. The relative amount of individual insecticidal crystal protein species produced by B.t. kurstaki and B.t. israelensis was not influenced by the carbohydrates supplied.