• Journal of Microbiology and Biotechnology
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• 제8권5호
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• pp.517-522
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• 1998

The cry1 gene content of a collection of Bacillus thuringiensis strains, which include new isolates from Malaysia and Indonesia, was determined by a multiplex PCR using a set of eight oligonucleotide forward primers specific to cry1Aa, cry1Ab, cry1Ac, cry1Ba, cry1Ca, cry1Da, cry1Ea, and cry1Fa genes, and two reverse primers, one specific to cry1Ab and the other common to the remaining cry1 genes. Two-thirds of the 59 strains screened were cry1 positive and contained one to four different genes. The cry gene profiles correlated well with toxicities of the strains to lepidopteran insects. The method can be used for rapid screening of a large number of new isolates as the total DNA extracted by boiling cells from single colonies can be used directly in the PCR. However, it is not suitable for follow-up monitoring of specific commercial strains after application in the field as the PCR product profiles of these strains could not be differentiated from those of new isolates.

• Journal of Microbiology and Biotechnology
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• 제17권9호
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• pp.1498-1503
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• 2007

To identify novel crystal proteins, Bacillus thuringiensis 2385-1 was isolated from Korean soil samples and characterized. The H-serotype of 2385-1 was identical to that of subsp. kenyae (H4a4c), and its crystal toxin was bipyramidal-shaped. However, 2385-1 showed a much higher toxicity towards Plutella xylostella and Spodoptera exigua larvae than subsp. kenyae. In addition, the crystal protein profile and plasmid DNA pattern of 2385-1 differed from those of subsp. kenyae. To verify the crystal protein gene types of 2385-1, a PCR-RFLP analysis was performed, and the results revealed that 2385-1 contained two novel cry1-type crystal protein genes, cryl-5 and cry1-12, in addition to the crylJal gene. The deduced amino acid sequences of cryl-5 and cry1-12 showed a 97.9% and 75.7% sequence similarity with the CrylAb and CrylJa crystal proteins, respectively. Among the novel crystal proteins, Cry1-5 showed a high toxicity towards P. xylostella and S. exigua larvae. In conclusion, B. thuringiensis 2385-1 is a new isolate in terms of its gene types, and should be a promising source for an insecticide to control lepidopteran larvae.

• Journal of Microbiology and Biotechnology
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• 제14권5호
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• pp.1057-1062
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• 2004

The entomopathogenic bacterium Bacillus thuringiensis is the most widely used biopesticide. Insecticidal proteins, coded by genes located in plasmids, form typical parasporal, crystalline inclusions during sporulation. We isolated a Bacillus thuringiensis strain having insecticidal activity against larvae of the house fly (M. domestica) from the soils at a pig farm in Korea, and named it Bacillus thuringiensis SM. The culture filtrate from Bacillus thuringiensis SM showed strong lethality (83.3%) against M. domestica larvae. The parasporal crystal is enclosed within the spores' outermost envelope, as determined by transmission electron microscopy, and exhibited a bipyramidal form. The crystal proteins of strain SM consisted of five proteins with molecular weights of approximately ~130, ~80, ~68, ~42, and ~27 kDa on a 10% SDS-PAGE (major band, a size characteristic of Cry protein). Examination of antibiotic resistance revealed that the strain SM showed multiple resistant. The strain SM had at least three different plasmids with sizes of 6.6, 9.3, and 54 kb. Polymerase chain reactions (PCRs) revealed the presence of cry1, cry4A2, and cry11A1 genes in the strain SM. The cry1 gene profile of the strain SM appeared in the three respective products of 487 bp [cry1A(c)], 414 bp [cry1D], and 238 bp [cry1A(b)]. However, the strain SM has not shown the cry4A2 md cry11A1 genes. In in vivo toxicity assays, the strain SM showed high toxicity on fly larvae (M. domestic) [with $LC_{50}$ of 4.2 mg/ml, $LC_{90}$ of 8.2 mg/ml].

• 한국미생물·생명공학회지
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• 제17권2호
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• pp.142-147
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• 1989

나비목 유충에 독성이 강한 균으로 알려진 Bacillus thuringiensis serovar. kurstaki HD73 을 ethidium bromide(0.02$\mu\textrm{g}$/$m\ell$)처리와 자연적 curing에 의한 내독소 유전자의 위치를 확인하여 변이주간 내독소 생성능을 간이 선별할 수 있는 배지를 선발한 다음 국내 토양에서 분리한 KBS722 균주에 적응하여 그 내독소 단백질 유전자의 위치를 확인한 결과를 요약하면 다음과 같다. HD73-NRRL과 Dul-mage박사로 분양 받은 균주는 약 7.4, 7.1, 8.1, 11. 3, 75kb 및 크기가 75kb와 비슷하고 copy수가 적은 또 하나의 plasmid로 전부 6개의 plasmid를 보유하고 있었으며 IPL 균주는 약 4.0과 70kb plasmid를 더 보유하는 것으로 나타났다. 상기 HD 73 균주들의 내독소 단백질 크기는 모두 133KD 정도였고 HD73의 내독소 유전자는 변이주간 내독소의 현미경 검경과, immunoblotting plasmid DNA 의 전기영동결과 75kb상에 있는 것으로 나타났다. 이들 변이주들을 potato dextrose agar, starch agar, spizizen casamino acid glucose 와 nutrient agar 평판배지에 접종하여 균형태를 관찰하였을 때 내독소 비형성균(Cry-)은 starch agar 배지에서만 반투명하고 균 군락의 색깔이 엷은 회색을 띄었다. 한편 국내 분리균 KBS722를 novobiocin(3$\mu\textrm{g}$/$m\ell$)으로 plasmid를 curing시켜 상기 4가지 배지에 도달했을때 nutrient agar배지에서만 Cry 변이주가 반투명하고 엷은 회색을 나타내었다. KBS722의 내독소유전자는 약 225kb의 plasmid상에 있는 것으로 나타났으며 in vitro에서 쉽게 Cry$^+$주와 Cry$^-$주의 판별이 가능하였다.

• International Journal of Industrial Entomology and Biomaterials
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• 제11권1호
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• pp.57-61
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• 2005

A strain of Bacillus thuringiensis that showed signifi­cantly high toxicity to Plutella xylostella was isolated from a dust sample collected from Chinese tobacco warehouse and characterized. The isolate named B. thuringiensis LY-99 was determined to belong to subsp. alesti (H3a3c) by an H antisera agglutination test and produced bipyramidal inclusions. Plasmid and crystal protein patterns of the LY-99 were different from those of the reference strain, subsp. alesti. PCR analysis with specific primers revealed that this isolate contained abundant cry genes including crylAa, crylAc, crylB, crylD, crylE, crylF and cry2 genes, which was absolutely different from cry gene profile of the subsp. alesti. In addition, insecticidal activity of the LY-99 against P. xylostella larvae was about 44 times higher than that of the subsp. alesti.