• Journal of Life Science
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• v.7 no.2
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• pp.95-106
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• 1997

The moderately alkalophilic bacterium, identified as Bacillus sp. S-1 , was isolated from soils and effectively secrete extracellular pullulanase. The isolate was moderately alkalophilic since enzyme production occurred at pHs from 6.0 to 10.0. Extracellular crude enzymes of the isolate gave maltotriose as the major product from soluble starch and pullulan hydrolysis. Compared to other alkalophilic microbes, this isolate secreted extremely high concentration(7.0 units/ml) of pullulanase. The purified pullulanase was moderately alkalophilic and thermoactive; optimal activity was detected at pH 8.0-10.0 and between 50-60$^{\circ}$C. Even at pH 12.0, 10% of S-1 pulluanase activity remained and the strain had broad pH ranges and moderate thermo-stability for their enzyme activities. These results indicate that the new isolate have potential as producer of pullulanase for use in the starch industry.

• 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.

• Korean journal of applied entomology
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• v.34 no.3
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• pp.243-248
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• 1995

In order to isolate naturally occurring novel Bacillus thuringiensis strains, we investigated the distribution of B. thuringiensis from granary which exist in Kyong-gi province, Korea. A total of 146 strains of B. thuringiensis producing spore and crystal wre isolated. The toxicity of B. thuringiensis isolates was examined against lepidopteran larvae (Bombyx mori), dipteran larvae (Culex pipiens) and coleopteran larvae (Sitophilus oryzae.), respectively. The results showed that a large number of B. thuringiensis isolates from granary dusts were isolated and most isolates wer toxic to lepidopterous larvae. Also, non-toxic B. thuringiensis isolate was common. In order to isolate many B. thuringiensis, therefore, it suggested that granary is favorable locality.

• Microbiology and Biotechnology Letters
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• v.25 no.6
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• pp.546-551
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• 1997

A bacterium producing the extracellular cellulases was isolated from soil and has been identified as Bacillus sp. The isolate, named Bacillus sp. 79-23, was shown to be very similar to B. subtilis on the basis of its biochemical properties. The carboxymethyl cellulase (CMCase) of culture supernatant was most active at 60$\circ$C and pH 6.0, and retained 90% of its maximum activity at pH 7.0. The additional carbon sources affected the CMCase productivity than nitrogen sources in the culture medium. The carbon sources including wheat bran, rice straw, maltose and glucose increased the enzyme productivty. Especially, the maximum CMCase production was 5.2 units/ml in LB medium supplemented with 3% (w/v) wheat bran, which was 13-folds more than that in LB medium. It was found that the enzyme production was in association with the growth of Bacillius sp. 79-23. But, whean bran did not affect the growth of isolate, suggesting that increasement of CMCase production was owing to the induction of CMCase biosynthesis by wheat bran. In addition, both water-soluble and insoluble components of wheat bran was involved in induction of CMCase biosynthesis.

• Korean Journal of Microbiology
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• v.46 no.3
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• pp.270-277
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• 2010

In order to manufacture Bacillus cereus-free fermented soybean products, an antimicrobial agentproducing isolate against B. cereus was obtained from 150 traditionally fermented soybean products. The morphological and biochemical tests and the phylogenetic relationship among 16S rRNA gene sequences indicated that the isolate named as the strain SCK 121057 was most closely related to Bacillus licheniformis. The B. licheniformis isolate began to produce the antimicrobial agent after 48 h of incubation. The agent was nonproteinaceous and insensitive to heat, long term storage and protease K. Electron microscopic observation indicated that the agent attacked the membrane of B. cereus, leaving the ghost cell. The isolate inhibited growth of B. subtilis, Lactobacillus brevis and various types of pathogenic strains including Escherichia coli, E. faecalis, Micrococcus luteus, Staphylococcus aureus, Aspergillus flavus, A. ochraceus, and A. parasiticus as well as B. cereus. After coinoculation of B. licheniformis SCK 121057 and B. cereus in the ratio (as the basis of CFU/g sample) of 10 to 1 on the surface of cooked soybeans, cell numbers of B. cereus had been dramatically reduced after 31 days of incubation compared to those of single inoculation of B. cereus.

• Mycobiology
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• v.40 no.1
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• pp.59-65
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• 2012

Antagonistic microorganisms against $Rhizoctonia$ $solani$ were isolated and their antifungal activities were investigated. Two hundred sixteen bacterial isolates were isolated from various soil samples and 19 isolates were found to antagonize the selected plant pathogenic fungi with varying degrees. Among them, isolate C9 was selected as an antagonistic microorganism with potential for use in further studies. Treatment with the selected isolate C9 resulted in significantly reduced incidence of stem-segment colonization by $R.$ $solani$ AG2-2(IV) in Zoysia grass and enhanced growth of grass. Through its biochemical, physiological, and 16S rDNA characteristics, the selected bacterium was identified as $Bacillus$ $subtilis$ subsp. $subtilis$. Mannitol (1%) and soytone (1%) were found to be the best carbon and nitrogen sources, respectively, for use in antibiotic production. An antibiotic compound, designated as DG4, was separated and purified from ethyl acetate extract of the culture broth of isolate C9. On the basis of spectral data, including proton nuclear magneric resonance ($^1H$ NMR), carbon nuclear magneric resonance ($^{13}C$ NMR), and mass analyses, its chemical structure was established as a stereoisomer of acetylbutanediol. Application of the ethyl acetate extract of isolate C9 to several plant pathogens resulted in dose-dependent inhibition. Treatment with the purified compound (an isomer of acetylbuanediol) resulted in significantly inhibited growth of tested pathogens. The cell free culture supernatant of isolate C9 showed a chitinase effect on chitin medium. Results from the present study demonstrated the significant potential of the purified compound from isolate C9 for use as a biocontrol agent as well as a plant growth promoter with the ability to trigger induced systemic resistance of plants.

• The Korean Journal of Pesticide Science
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• v.17 no.4
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• pp.428-434
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• 2013

An isolate of Bacillus amyloliquefaciens subsp. plantarum CC110 was selected as an effective antagonist for biological control of cucumber downy mildew caused by Pseudoperonospora cubensis. Temperature range for growth of CC110 isolate was $7.5{\sim}55.0^{\circ}C$, and its optimal temperature at $36.6^{\circ}C$. pH range for growth of CC110 isolate was 4.5~9.5, and its optimal pH at 7.0. In this study, the most effective sources of carbon and nitrogen for growth of CC110 isolate were fructose and yeast extract, respectively. The volatile of CC110 isolate was found to be effective to control downy mildew on cucumber showing no diseased area whereas that of control was 13.2% using the I plate bioassay. The culture broth and cells of isolate CC110 cultured in TSB media for 48 hours at $28^{\circ}C$ inhibited occurrence of cucumber downy mildew. The cells and culture broth were transformed into sporangia of P. cubensis by in observation under light microscope and scanning electron microscope.

• Mycobiology
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• v.41 no.4
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• pp.234-242
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• 2013

A total of 62 bacterial isolates were obtained from Gomsohang mud flat, Mohang mud flat, and Jeju Island, Republic of Korea. Among them, the isolate CNU114001 showed significant antagonistic activity against pathogenic fungi by dual culture method. The isolate CNU114001 was identified as Bacillus amyloliquefaciens by morphological observation and molecular data analysis, including 16SrDNA and gyraseA (gyrA) gene sequences. Antifungal substances of the isolate were extracted and purified by silica gel column chromatography, thin layer chromatography, and high performance liquid chromatography. The heat and UV ray stable compound was identified as iturin, a lipopeptide (LP). The isolate CNU114001 showed broad spectrum activity against 12 phytopathogenic fungi by dual culture method. The semi purified compound significantly inhibits the mycelial growth of pathogenic fungi (Alternaria panax, Botrytis cinera, Colletotrichum orbiculare, Penicillium digitatum, Pyricularia grisea and Sclerotinia sclerotiorum) at 200 ppm concentration. Spore germ tube elongation of Botrytis cinerea was inhibited by culture filtrate of the isolate. Crude antifungal substance showed antagonistic activity against cucumber scleotiorum rot in laboratory, and showed antagonistic activity against tomato gray mold, cucumber, and pumpkin powdery mildew in greenhouse condition.

• Korean Journal of Food Science and Technology
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• v.31 no.3
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• pp.734-738
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• 1999

Bacterial strain showing the ropy characteristics was isolated from Korean wheat bread. Morphology of the isolate was rod and biochemical test revealed that the isolate was Bacillus subtilis. Growth of rope bacteria was about the same as other Bacillus species and inhibited below pH 5.6. Rope bacteria isolated from Korean wheat bread could not survive under the heat treatment of 10 min at $100^{\circ}C$, but could survive at $90^{\circ}C$.

• The Microorganisms and Industry
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• v.14 no.1
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• pp.17-20
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• 1988

A genetic analysis of the complex Bacillus subtilis transcriptional apparatus is essential to understand the function, regulation, and interaction of the transcriptase components during growth and sporulation. This approach in Escherichia coli has uncovered fundamental mechanisms regulating gene expression Cole and Nomura, 1986; Lindahl and Zengel, 1986) and an analysis of the B. subtilis transcriptase will allow comoparison of the E.coli system to another bacterium that has evolved under different selective pressures. To this end we used antibody probes to isolate the alpha, beta, and beta' core subunit genes from a .lambda.gtill expression vector library. To address the question of function ans regulation of the minor sigma factors that confer promoter specifity on the polymerase core (Losick et al., 1986), we used the same approach to isolate the gene for the 37,000 dalton sigma factor, sigma-37.