• Journal of Life Science
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• v.19 no.6
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• pp.744-750
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• 2009

A bacterial strain producing highly viscous extracellular polysaccharide was isolated from soil. Through morphological, physiological and chemotaxonomical studies, it was identified as a Bacillus sp. and named Bacillus sp. PS-12. The extracellular polysaccharide, named PS-12 was purified by ethanol precipitation, cetylpyridinium chloride (CPC) precipitation and gel permeation chromatography. The purified polysaccharide was found to consist of glucose, mannose, galactose, and fucose, with a molar ratio of approximately 7:3.2:2:1, respectively. PS-12 was investigated for its immunostimulating activity on murine macrophage RAW264.7 cells using an ELISA assay. PS-12 stimulated the production of TNF-${\alpha}$ to a level 50 times greater than the control and also induced 1L-6 secretion in a dose-dependent manner. The cytotoxicity on RAW264.7 cells by PS-12 was relatively low with 10% cytotoxicity at 2 ${\mu}g$/ml. These results indicate that PS-12 is less cytotoxic to immune cells and possess immunomodulating activity in which it can produce cytokines including TNF-${\alpha}$ and 1L-6 from macrophages.

• Korean Journal of Food Science and Technology
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• v.2 no.2
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• pp.61-67
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• 1970

The growth characteristics of Candida tropicalis KIST 359, isolated from soil samples collected at an oil depot in Korea, have been studied by cultivating batches under varying conditions. The conclusions of the study were: 1. The yeast easily assimilates hydrocarbons in a range of $C_{14}-C_{17}$, and the optimum cultivation temperature and pH are $30^{\circ}C$ and 5.5, respectively. 2. Using this strain of micro-organism, gas oil gives a higher cell yield than kerosine and with gas oil except urea all other nitrogen sources $(NH_4NO_3,\;NH_4Cl,\;(NH_4)_2SO_4\;and\;(NH_4)_2HPO_4)$ similarly support a satisfactory growth of the yeast. 3. The highest yield is obtained with a gas oil level of 10%(v/v), and concentrations of nitrogen source and $MgSO_4{\cdot}7H_2O$ of 0.5 and 0.05%(w/v), respectively. 4. The protein content of dried yeast cells is 59.8%. Its amino acid composition can be compared well with that of FAO provisional patterns, but with a low methionine and a high lysine content.

• Research in Plant Disease
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• v.11 no.2
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• pp.152-157
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• 2005

In a course of searching for biofungicide to control crisphead lettuce bottom rot caused by Rhizoctonia solani, we have isolated an antagonistic bacterium from lettuce rhisophere soil. A total of 702 bacterial isolates were isolated and tested for in vitro growth inhibition of R. solani. Seven strains appeared to have strong antagonistic effect against R. solani in in vitro growth inhibition assay. In the pot experiments, a strain BW-13 showed the most potent disease control effect on the both lettuce seedlings and adults plants. Therefore, the BW-13 was selected as a biocotrol candidate against crisphead lettuce bottom rot. Based on its morphology, physiological characteristics, and 165 rRNA gene analysis, the BW-13 was finally identified as Stenotrophomonas maltophilia. This study indicated that S. maltophilia BW-13 could be used as a biocontrol agent to control crisphead lettuce bottom rot.

• Journal of Animal Science and Technology
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• v.51 no.2
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• pp.171-176
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• 2009

A bacterial strain producing intracellular phytase was isolated from cultivable soil near cowsheds and identified as a fluorescent Pseudomonas sp. BUN1. The BUN1 phytase, partially purified by cation and anion exchange chromatography, exhibited its optimal activity at $40^{\circ}C$ and pH 5.5. As for substrate specificity, it was very specific for phytate and showed little activity on other phosphorylated conjugates. Its activity was greatly inhibited by metal ions such as $Cu^{2+}$, $Cd^{2+}$, and $Zn^{2+}$. Addition of corn starch to PSM (phytasesynthetic medium) [0.5% sodium phytate, 0.5% $(NH_4)_2SO_4$, 0.5% KCl, 0.01% $MgSO_4\cdot7H_2O$, 0.01% $CaCl_2\cdot2H_2O$, 0.01% NaCl, 0.001% $FeSO_4\cdot7H_2O$, 0.001% $MnSO_4\cdot4H_2O$; pH 6.5] for the phytase production significantly induced its enzyme activity in comparison with other carbon sources tested.

• Microbiology and Biotechnology Letters
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• v.33 no.3
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• pp.194-199
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• 2005

In oder to select an antifungal substance-producing antagonistic bacterium against Fusarium oxysporum casuing fusarium wilt on tomato, strain BK4 was isolated from local soil of Gyeoungbuk and was identified as Bacillus thuringiensis by 16s rDNA analysis, biochemical test, and Mcirolog TM 3.0 System. The antibiotic of B. thuringiensis BK 4 was highly produced at $30^{\circ}C$ in nutrient broth (pH 9.0). The crude antibiotic was even stable at $121^{\circ}C$ and more stable at slight alkalic condition than acid condition. It was also remained $50{\%}$ activity at pH 3.0. B. thuringiensis BK4 showed the inhibition of spore germination and the biocontrol ability against F. oxysporum causing fusarium wilt of tomato in vivo test. According to these results, B. thuringiensis BK4 was enough to use with a microbial agent for biocontrol against fusarium wilt.

• Geotechnical Engineering
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• v.13 no.4
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• pp.37-54
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• 1997

This paper is to investigate the bearing capacity and the failure mechanism of slope subjected to strip surcharges adjassent to embankment slope of sandy soil. Parametric model tests under plain strain condition were performed by changing width of footing, relative density of slope materials, and position of footing from the crest of slopes. For model tests, Jumunjin standard sand was used as the slope material and its relative density was 45% and 70%, respectively. The angle of slope was formed with 1 : 1.5 and 1 2. Rigid model footings, made of aluminuu were used with their widths of 4, 7, 10 and 12cm. For the position of model footing, position ratios, distance of model footing from the crest of slope divided by footing width, were 0, 0.5, 1, 2, 3, 4, 5. Failure mechanism was observed by using ink colored sands and markers inserted in model slopes. Ultimate bearing capacity obtained from tests was analyzed and compared with limit equilibrium method, limit analysis method and empirical equation. Characteristics of load-settlement curves and failure mechanism were also analyzed and compared with the existing theories. Thus, their effects on ultimate bearing capacity of model footing adjacent to slope were assessed.

• Journal of Life Science
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• v.25 no.2
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• pp.189-196
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• 2015

Bacterial diversity was studied in the rhizosphere of Suaeda japonica Makino, which is native to Suncheon Bay in South Korea. Soil samples from several sites were diluted serially, and pure isolation was performed by subculture using marine agar and tryptic soy agar media. Genomic DNA was extracted from 29 pure, isolated bacterial strains, after which their 16S rDNA sequences were amplified and analyzed. Phylogenetic analysis was performed to confirm their genetic relationship. The 29 bacterial strains were classified into five groups: phylum Firmicutes (44.8%), Gamma proteobacteria group (27.6%), Alpha proteobacteria group (10.3%), phylum Bacteriodetes (10.3%), and phylum Actinobacteria (6.8%). The most widely distributed genera were Bacillus (phylum Firmicutes), and Marinobacterium, Halomonas, and Vibrio (Gamma proteobacteria group). To confirm the bacterial diversity in rhizospheres of S. japonica, the diversity index was used at the genus level. The results show that bacterial diversity differed at each of the sampling sites. These 29 bacterial strains are thought to play a major role in material cycling at Suncheon Bay, in overcoming the sea/mud flat-specific environmental stress. Furthermore, some strains are assumed to be involved in a positive interaction with the halophyte S. japonica, as rhizospheric flora, with induction of growth promotion and plant defense mechanism.

• Journal of Life Science
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• v.21 no.4
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• pp.554-560
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• 2011

This study was performed to investigate the effects of microbial augmentation on the biological treatment of paper mill wastewater. Three bacteria (KN11, KN13, KN27) capable of degrading aromatic compounds and a bacterial strain (GT21) producing an extracellular cellulase were isolated from soil and wastewater by selective enrichment culture. Through morphological, physiological, and biochemical taxonomies, isolated strains of KN11, KN13, KN27, and GT21 were identified as Acinetobacter sp., Neisseria sp., Bacillus sp., and Pseudomonas sp. and named Acinetobacter sp. KN11, Neisseria sp. KN13, Bacillus sp. KN27, and Pseudomonas sp. GT21, respectively. For analysis of non-biodegradable and chemical oxygen demand (COD)-increasing matter in a paper mill wastewater, we utilized GC/MS to detect aromatic compounds and their derivatives containing several substituted functional groups. The microbial augmentation, J30 formulated with the mixture of bacteria including Acinetobacter sp. KN11, Neisseria sp. KN13, Bacillus sp. KN27, and Pseudomonas sp. GT21, was used for the treatment of paper mill wastewater. The optimum temperature and pH for COD removal of the microbial augmentation, J30, were $30^{\circ}C$ and 7.5, respectively. For evaluation of the industrial applicability of the microbial augmentation, J30 in the pilot test, treatment efficiency was examined using paper mill wastewater. The microbial augmentation, J30, showed a COD removal rate of 87%. On the basis of the above results, we designed the wastewater treatment process of the activated sludge system.

• Korean Journal of Plant Resources
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• v.29 no.1
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• pp.39-45
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• 2016

Pink Rot on melon and White Stain Symptom on grape are caused by Trichothecium roseum, one of the most important diseases of grape and melon. These diseases have been occurred in national-wide in Korea and causes irreversible damage on the grape and the melon at harvest season. This research presents the evaluation of the capacity of Bacillus subtillis HK2 to protect both melon and grape against T. reseum and establishes its role as a biocontrol agent. In this study, we isolated a Bacillus strain HK2 from rhizosphere soil, identified it as Bacillus subtillis by 16S rRNA analysis and demonstrated its antifungal activity against T. roseum. Under I-plate assay it was observed that the effect of hyphal growth inhibition was not due to production of volatile compounds. The optimum culture condition of HK2 was found at 30℃ and initial pH of 7.0. Application of HK2 culture suspension reduced 90.2% of white stain symptom on grape as compared to control, resulting in greater protection to grape against T. roseum infestation. Butanol extract of HK2 culture purified using flash column chromatography. The antifungal material was a polar substance as it showed antifungal activity in polar elute. Therefore, our results indicated a clear potential of B. subtilis HK2 to be used for biocontrol of Pink rot in melon and white stain symptom on grape caused by T. roseum.

• Microbiology and Biotechnology Letters
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• v.26 no.3
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• pp.195-199
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• 1998

AH alkalophilic Bacillus SP. AIk-7, isolated from soil, produced ethylene. The characteristics of this microorganism is the ability to grow well under the alkaline condition, at pH 10.3. This strain is similar to Bacillus alkalophilus in terms of morphological, physiological and biological characteristics. In observation of relationship of cell growth and ethylene production according to incubation times, the ethylene synthesis mostly occur from the late exponential phase to the death phase of growth. The purpose of this paper is to study the effects of various substrates on the biosynthesis of ethylene in the intact cell and the cell-free system by the Bacillus sp. AIk-7. In both intact cell and cell-free extract, optimum conditions for ethylene production was achieved at pH 10.3 and 3$0^{\circ}C$. Ethylene was effectively produced from L-Met and 1-aminocyclopropane-1-carboxylic acid (ACC). In this case, ACC as the substrate on ethylene production were two fold higher than L-met at each concentration of substrates. On the other hand, the cell-free ethylene-forming system was used as a tool for the elucidation of the biochemical reaction involved in the formation of ethylene by Bacillus sp. AIk-7. Ethylene production in the cell-free system required the presence of manganese and cobalt ion to be stimulated a little. The result obtained in this work suggests that L-met and ACC may be a precursor more directly related to bacterial ethylene production than any other substrates tested.