• Microbiology and Biotechnology Letters
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• v.16 no.2
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• pp.168-173
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• 1988

Immunological analysis between endotoxin proteins produced by Bacillus thuringiensis serovar. kurstaki HD1 and HD73 have been investigated by using polyclonal antibodies. The antisera against the endotoxin proteins were prepared from rabbits injected with the endotoxin protein antigens. When about 2mg/$m\ell$ of the antigens were injected for 7 times, the titers were highest. The stability of the antigens was reduced to about 50% after 9 days incubation at 4$^{\circ}C$. The sensitibity of endotoxin protein from B. thuringiensis HD1 and HD73 by indirect ELISA was 50ng/$m\ell$ and 400ng/$m\ell$, respectively. The cross reaction of antiserum appeared that anti-HD1 partialy reacted with crystal protein but anti-HD73 reacted with HD1 endotoxin about 100%.

• 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.

• Microbiology and Biotechnology Letters
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• v.26 no.4
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• pp.369-372
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• 1998

Microbial insecticide formulations were prepared by liquid and semi-solid fermentations using Bacillus thuringiensis subsp. kurstaki, HL-106 (BTK-HL106), B. thuringiensis subsp. israelensis HL-63 (BTI-HL63) and B. sphaericus 1593 (BS-1593) strains. The liquid fermentation medium contained molasses 2%, dextrose 1.5%, peptone 2%, D-xylose 0.025%, CaCl$_2$ 0.1%, K$_2$HPO$_4$ 0.1%, KH$_2$PO$_4$ 0.1%, MgSO$_4$$.$7H$_2$O 0.03%, FeSO$_4$$.$7H$_2$O 0.002%, ZnSO$_4$$.$7H$_2$O 0.02%. The composition of the semi-solid fermentation medium was rice bran 45.2%, zeolite 31%, yeast powder 0.02%, corn powder 5%, dextrose 3%, lime 0.3%, NaCl 0.06%, CaCl$_2$ 0.02%, and H$_2$O 15.42%. Insecticide formulations produced in the liquid fermentation named BTK-HL106, BTI-HL63 and BS-1593 pesticides and those in the semi-solid fermentation were designated as BTK-HL106-1, BTI-HL63-1 and BS-1593-1 pesticides, respectively. The number of spore (endotoxin crystals) was 2.65${\times}$10$\^$9/ spores per $m\ell$ in the BTK-HL106 and 3.5${\times}$10$\^$10/ in the BTK-HL106-1 3.8${\times}$10$\^$9/ spores in the BTI-HL63 and 7.0${\times}$10$\^$10/ in the BTI-HL63-1, and 7.5${\times}$10$\^$9/ in the BS-1593 and 1.4${\times}$10$\^$10/ in the BS-1593-1. The spores in the BS-1593 formulation was produced two times more than the other formulations. The spores in the BTI-HL63-1 were contained twice than those in the BTK-HL106-1, and five times than those in the BS-1593-1. The results indicated that spore (endotoxin crystals) productions in the semi-solid fermentation increased about ten times than those in the liquid fermentations. $LC_{50}$s of the BTI-HL63 and BS-1593 were 4.5 $\mu\textrm{g}$, and those of the BTI-HL63-1 and BS-1593-1 were 1.5 $\mu\textrm{g}$. $LC_{50}$ of the BTK-HL106 was 1.5 mg and that of the BTK-HL106-1 was 0.9 mg. The $LC_{50}$s of the formulations in the semi-solid fermentations showed about two to three times higher than those in the liquid fermentations.

• BMB Reports
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• v.37 no.3
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• pp.304-313
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• 2004

Three-dimensional (3D) models for the 65-kDa activated Cry4A and Cry4B $\delta$-endotoxins from Bacillus thuringiensis subsp. israelensis that are specifically toxic to mosquito-larvae were constructed by homology modeling, based on atomic coordinates of the Cry1Aa and Cry3Aa crystal structures. They were structurally similar to the known structures, both derived 3D models displayed a three-domain organization: the N-terminal domain (I) is a seven-helix bundle, while the middle and C-terminal domains are primarily comprise of anti-parallel $\beta$-sheets. Circular dichroism spectroscopy confirmed the secondary structural contents of the two homology-based Cry4 structures. A structural analysis of both Cry4 models revealed the following: (a) Residues Arg-235 and Arg-203 are located in the interhelical 5/6 loop within the domain I of Cry4A and Cry4B, respectively. Both are solvent exposed. This suggests that they are susceptible to tryptic cleavage. (b) The unique disulphide bond, together with a proline-rich region within the long loop connecting ${\alpha}4$ and ${\alpha}5$ of Cry4A, were identified. This implies their functional significance for membrane insertion. (c) Significant structural differences between both models were found within domain II that may reflect their different activity spectra. Structural insights from this molecular modeling study would therefore increase our understanding of the mechanic aspects of these two closely related mosquito-larvicidal proteins.

• Korean journal of applied entomology
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• v.28 no.4
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• pp.229-236
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• 1989

A combined field release of indigenous larvivoroug fish (Aplocheilus latipes) and hybrid herbivore (Tilapia mossambicus miloticus) was conducted to determine the effectiveness of biological control, in particular, against malaria vector (anopheles sinensis), breeding in weedy habitat of rice fields at the University rice paddies at Suwon during the period of June through September in 1988. A combined fish introduction at the release rate of 2.0 fish per $M^{2}$ for Aplocheilus and 1-pair $10M^{2}$ water surface for Tilapia resuited in 70.8% Anopheles larval reducton in a week period, the rates of rontrol increased to 73. 5% and 80.2% in 4th and 5th week respectively after the fish introdurtion, maintaining mosquito suppression in range of 80~82% control after the 5th week against Anopheles and Culex spp. combined. In a single fish treatment with Aplocheilus at 2.0 $fish/M^{2}$ release rate, Anopheles larval reduction ranged on the average 51.4~56.5%in 4 wrek period which was later integratpd with B.t.i. (Rl53.78) treatment at 1.0 kg/ha dosage rate to suppress vector mosquito population down and the the results was compared with that of combined fish introdurtion.

• Korean Journal of Environmental Biology
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• v.38 no.1
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• pp.189-196
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• 2020

Mosquitos serve as vectors for diseases, causing inconvenience as well as a threat to human life and health. Concern about mosquitos introducing and spreading new diseases has been intensifying. We observed a variety of mosquito habitats based on land cover classification from Korea's Ministry of Environment, and the mosquito species that could appear were classified according to the each habitat type. Finally, we suggested the best control methods for each type of habitat considering habitat characteristics and the ecological traits of mosquitos. Urban areas harbor various habitats for pests, contributing significantly to mosquito habitats. Control must be performed regarding larva and adults because various sources for habitats exist. Public mosquito control programs such as educational training, as well as information brochures can be effective in managing mosquito populations and public health. Agricultural areas show high densities of mosquito larva to lentic zones such as reservoirs, wetlands, paddy fields. So, biological control using natural predators may be effective in controlling mosquito populations. Forests are major habitats for Aedes albopctus, so physical controls should be deployed for residents living nearby, and excessive deforestation should be minimized. Other areas including aquatic ecosystems should be adopted regarding biological control using Bti (Bacillus thuringiensis var. israelensis) and chemical control for eradicating mosquitos. We classified habitats into four types of land cover patterns considering ecological traits and habitat preference, and suggest adequate control methods for each habitat type. Our suggestion can be used to positively contribute toward effective managing mosquito's density and reducing the damage to public health.

• Korean Journal of Environmental Biology
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• v.37 no.4
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• pp.600-606
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• 2019

The study site was the camping area in the Hwarang Amusement Park in Danwon-gu, Ansan-si. Study activities were conducted three times a week from July 20, 2018, to August 1, 2018. A control site, natural enemy site, and Bti(Bacillus thuringiensis israelensis) site were selected. The analyses included habitat environment and species composition analyses, community analysis, correlation analysis, and similarity analysis. The water quality analysis found no significant difference in water quality over the study period (p>0.05). A total of 4,818 individuals, 38 species, 22 families, and 11 orders were observed during the study period. The natural enemy site observed during the study period had a similar species composition as the control site. The Bti site differed from other sites by the low number of species and individuals present. According to the community analysis, the natural enemy site was a stable community and the Bti site was an unstable community during the study period. Diptera showed negative associations with temperature and water temperature and mosquito larvae showed significant correlations with temperature and water temperature. The similarity analysis showed that the control site and the natural enemy site were 61.11-73.68% and the Bti site showed 30.77-56.00% similarity.

• Korean journal of applied entomology
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• v.28 no.3
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• pp.167-174
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• 1989

A confined field assessment on the integrated control of vector mosquitoes (Anopheles sinen- sis and Culex tritaent'orhynchus) was conducted by timely treatment of Bacillus thuringiensis(H-14) formulation in the presence of larvivorous fish (Aplocheilus lalipes) in natural rice fields of $30,000M^2$ at Yongam, South Korea Cholla Province from July through October in 1988. In presence of larvivorous fish (Aplocheilus) at lower density of 0.6 fish per $M^2$ water surface, mosquito vector control rates ranged 55. 0~57. 6% from July through August, and when the mosquio density started to increase with over 10 larvae on the average per sample, B.t.(H-14) formulation treatment at the rate of 1. 0 Kg/ha made 100% vectors reduc¬tion in 24 hours, the control sustained above 98% until the test was terminated on October 11th. In the fish introduced rice paddies with Aphyocypris chinensis at the density of above 1. 5 fish per $M^2$, a satisfactory degree of vector control was obtained by 88. 2~96. 7% in 2 week period until September 21st. In the absence of larvivorous fishes, B.t. (H-14) treatment made 100% control in 24 hours, however, vector population rebound appeared in day 7, required to make additional treatment to suppress population down.

• Korean journal of applied entomology
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• v.24 no.1 s.62
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• pp.45-50
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• 1985

The use of a modified procedure for the isolation of extrachromosomal DNA of low to high molecular weight, followed by agarose gel electrophoresis of the crude lysates, provided a simple screening procedure for detecting plasmids ranging in molecular weights from approximately 1 to more than 135 megadaltons from serovars of Bacillus thuringiensis. The procedure provides for a relatively large-volume stable lysate for isolation of plasmids for restriction endonuclease mapping and cloning procedures. The method was used for screening of plasm ids in 6 differenentially effective serovars of B. thuringiensis toxic to dipteran and lepidopteran insects. Relatively large plasmid DNAs of masses above 50 megadaltons (Mdal) were isolated from all of the serovars examined using this technique. The number of extrachromosomal DNAs detected in serovars of B. thuringiensis was 8 for israelensis, 10 for kurstaki, 13 for aizawai, 2 for dendrolimus, 1 for finitimus, and 6 for yunnanensis. Smaller plasmid DNAs were isolated in four of the six serovars that ranged in mass down to approximately 2 Mdal.