• Journal of the Korean Geotechnical Society
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• v.21 no.7
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• pp.5-12
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• 2005

In order to investigate the strength and deformation anisotropy of compacted decomposed granite soils, a series of unsaturated-drained triaxial compression tests were performed. The sample used in the study was decomposed granite soil from Shimonoseki in Yamaguchi prefecture. The sample had three different angles of the axial (major principal) direction to the sedimentation plane (compaction plane), 0, 45 and 90 degrees. The compression strain of specimens subjected to isotropic compression was strongly influenced by the sedimentation angle. In addition, the time dependence was independent of the sedimentation angle in relation to the deformation behavior during the secondary compression process. The effect of the sedimentation angle on the triaxial compression strength and deformation was clear with low confining stress. Moreover, it was recognized that although the sedimentation angle and preparation methods were different, the dilatancy rate was relative to the increment of strength due to dilatancy. Therefore, it may be concluded that the compacted specimen has anisotropic mechanical properties similar to those of sand with initial fabric anisotropy.

• Korean Journal of Agricultural Science
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• v.14 no.1
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• pp.144-155
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• 1987

A potent fungus producing milk clotting enzyme with fairly weak proteolytic activity was isolated from various soil and sewage, which the selected strain, SA-101, was identified as Mucor sp. with microbiological characteristics. Its milk clotting enzyme production was maximized when grown on 10g of wheat bran media added to 8ml of tap water containing 0.1M HCl for 60hrs at $30^{\circ}C$. This enzyme production was stimulated by addition of 6% lactose, 0.05% NaCl and reached a maximal level of 9810 unit/g wheat bran. The crude enzyme product could be produced effectively by salting out with ammonium sulfate fractionation and lyophilization. The ratio of milk clotting activity to proteolytic activity of crude enzyme product was lower than Hansen rennet, but resembled to Meito rennet. The optimal temperature of milk clotting activity of crude enzyme product was abound $60^{\circ}C$ on a substrate of 10% reconstituted skim milk containing 1/100M $CaCl_2$.

• The Korean Journal of Mycology
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• v.44 no.3
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• pp.193-195
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• 2016

Korean ginseng (Panax ginseng) possesses various biological and pharmacological properties. Damping-off is a critical disease on ginseng seedlings, which is caused by the fungal pathogens Rhizoctonia solani and Pythium sp.. This disease is generally controlled by the application of fungicides, but also biological control is an efficient and environmentally friendly way to prevent ginseng damping-off. In a previous study, we screened soil-borne bacteria with potential applications as biological control agents for ginseng damping-off and selected the bacterial strain Streptomyces sp. A3265, producing antifungal substances guanidylfungin and methylguanidylfungin. In this study, we investigated control efficacy of Streptomyces sp. A3265 against ginseng damping-off in the field. As a result, the incidence of damping-off was significantly reduced when soaking ginseng seeds in the culture broth of Streptomyces sp. A3265.

• Korean Journal of Food Science and Technology
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• v.3 no.2
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• pp.89-93
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• 1971

Microorganisms producing milk-clotting enzyme were isolated from 1,506 strains which were collected from soil on the various places of Korea, and from strains which were already identified. Dothiorella ribis was taken as a good strain producing milk-clotting enzyme. When it is cultured on wheat bran, the optimum experimental conditions for the production of milk-clotting enzyme were consequently obtained as follows: 1) $30{\sim}35^{\circ}C$ of temperature and 4.0 of pH. 2) $60{\sim]80%$ of cultivating water to the weight of wheat bran. 3) addition of $(NH_4)_2SO_4$ as a nitrogen source, $NaCl\;and\;KH_2PO_4$ as an inorganic salt, and 3% of sucrose as a carbon source. 4) four days for a period of cultivation.

• Geotechnical Engineering
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• v.8 no.3
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• pp.23-36
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• 1992

The flat dilatometer(DMT) has been practically used as an in-situ test equipment. It is a simple, rapid and cost-effective tool to characterize the in-situ stress-strain-strength properties of various types of ground materials. However, the results of flat DMT should be validated with considerable data with respect to the known reference values for a specific site. In this study, the applicability of existing relationships which were established for other local deposits is verified by performing the tests in several clay deposits. To compare with the DMT results, field vane tests and cone penetration tests were also carried out in the same field as reference tests, and unconsolidated undrained tests, oedometer tests, and other fundamental material properties tests were conducted on the thin-walled tube samples in the laboratory. The results of the flat DMT combined with empirical correlations are used to estimate soil types, unit weights, coefficients of lateral earth pressure at rest, overconsolidation ratios, constrained moduli and undrained shear strengths of three clay local deposits. It was found that various geotechnical properties estimated from the flat DMT generally well agree with those from the reference tests.

• KSBB Journal
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• v.26 no.2
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• pp.100-106
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• 2011

Strain BCNU 5011 was isolated from forest soil samples collected in the Taebaek mountain in the Gangwon province, Korea. The biochemical, physiological and 16S rRNA sequence analysis strongly indicated that this isolate was most closely related to Paenibacillus polymyxa. A maximum production level of antimicrobial substances of Paenibacillus sp. BCNU 5011 was achieved under aerobic incubation at $30^{\circ}C$ for 3 days in SST broth.Paenibacillus sp. BCNU 5011 showed a broad spectrum of activity against Gram positive and Gram negative bacteria, including methicllinresistant Staphylococcus aureus (MRSA). Paenibacillus sp. BCNU 5011 was also shown to inhibit the growth of different potential human pathogenic bacteria and fungi in vitro. Peptide extract showed better antimicrobial activity than solvent extracts. But active antimicrobial compounds might be included in both peptide extract and solvent extracts. Further separation, purification and identification of active principles leads project to develop antimicrobial agents and anti-MRSA agents.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.6
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• pp.801-806
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• 2009

A species producing transglutaminase (EC 2.3.2.13) was isolated from forest soil and identified as Streptomyces platensis YK-2. The transglutaminase was purified from culture broth by 50% methanol precipitation, followed by successive chromatography on DEAE-Sephadex. The yield and purification-fold was 63.4% and 2.2-fold, respectively. The purified microbial transglutaminase (MTG) migrated as a single band of approximately 45 kDa upon sodium dodecyl sulfate polyacrylamide gel eletrophoresis. The isoelectric point determined by multichambered electrofocusing was pH $6.0{\sim}7.0$. The enzyme was strongly inhibited by $Hg^{++}$, but was activated by $Cd^{++}$, $Mg^{++}$, $Mn^{++}$, $Pb^{++}$ and reducing agents such as dithiothreitol and mercaptoethanol.

• Journal of Microbiology and Biotechnology
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• v.12 no.2
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• pp.189-195
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• 2002

Using Streptomyces sp. YU100 isolated from Korean soil, the fermentative production of phospholipase D was attempted along with its purification and characterization studies. When different carbon and nitrogen sources were supplemented in the culture medium, glucose and yeast extract were found to be the best. By varying the concentration of nutrients and calcium carbonate, the optimal culture medium was determined as 2.0% glucose, 1.5% yeast extract, 0.5% tryptone 0.3% calcium carbonate. During cultivation, the strain secreted most of the phospholipase D in the early stage of growth within 24 h. The phospholipase D produced in the culture broth exhibited hydrolytic activity as well as transphosphatidylation activity on lecithin (phosphatidylcholine). In particular, the culture broth showed 8.7 units/ml of hydrolytic activity when cultivated at $28^{\circ}C$ for 1.5 days. The phospholipase D was purified using 80% ammonium sulfate precipitation and DEAE-Sepharose CL-6B column chromatography, which produced a major band of 57 kDa on a 10% SDS-polyacrylamide gel with purity higher than 80%. The enzyme showed an optimal pH of 7 in hydrolytic reaction, and at pH 4 in a transphosphatidylation reaction. The enzyme activity increased until the reaction temperature was elevated to $60^{\circ}C$. The enzyme was relatively stable at high temperatures and neutral pH, but significantly unstable in the alkaline range. Among the detergents tested as emulsifiers of phospholipids, the highest enzyme activity was observed when 1.5% Triton X-100 was employed. However, no inhibitory effect by metal ions was detected. Under optimized reaction conditions, the purified enzyme not only completely decomposed PC to phosphatidic acid within 1 h, but also exhibited higher than 80% conversion rate of PC to PS by transphosphatidylation within 4 h.

• Microbiology and Biotechnology Letters
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• v.10 no.4
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• pp.275-281
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• 1982

One strain of Streptomyces sp. (AS-707) isolated from soil was found to produce a biologically active substance that showed a strong inhibitory activity against proteolytic enzymes viz. trypsin, papain, $\alpha$-chymotrypsin, Azotobacter protease, and Bacillus pretense. The substance was separated from culture filtrate by ion exchange column chromatography using Amberlite IRC-50 and CM-cellulose column chromatography. It was found that the recovery yield was 26% as activity basis. The substance was stable in wide pH range from 2.0 to 12.0 at 37$^{\circ}C$, but it was unstable in alkaline pH values at 6$0^{\circ}C$. The activity was thermostable to give 90% activity compared to the intact sample when it was treated at pH5.6 at 10$0^{\circ}C$ for 2 hours.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1979.04a
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• pp.113.2-114
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• 1979

$\beta-Galactosidase$ is an enzyme which catalizes hydrolysis of lactose, a natural substrate, to glucose and galctose and transferring some monosac-charide units to active acceptors as sugar or alcohol. The occurence of $\beta-Galactosidase$ is known in various microorganisms, animals and higher plants and has been studied by many investigatigators. Especially, a great deal of articles for the enzyme of E. coli have been presented in genetic control mechanism and induction-repression effects of proteins, On the other hand, in the dairly products industry, it is important to hydrolyes lactosd which is the principal sugar of milk and milk products. During the last few years, the interest in enzymatic hydrolysis of milk lactose has teen increased, because of the lactose intolerence in large groups of the population. Microbial $\beta-Galactosidases$ are considered potentially most suitable for processing milk to hydrolyse lactose and, in recent years, the immobilized enzyme from yeast has been examined. Howev, most of the microbial $\beta-Gal$ actosidase are intracellular enzymes, except a few fungal $\beta-Gala-$ ctosidases, and extracellular $\beta-Galactosidase$ which may be favorable to industrial applieation is not so well investigated. On this studies, a mold producing a potent extracellular $\beta-Galactosidase$ was isolated from soil and identified as an imperfect fungus, Beauveria bassians. In this strain, both extracellular and intracellular $\beta-Galactosidases$ were produced simultaneously and a great increase of the extracellular production was acheved by improving the cultural conditions. The extracellular enzyme was purified more than 1, 000 times by procedures including Phosphocellulose and Sephadex G-200 chromatographies. Several characteristics of the enzymewas clarified with this preparation. The enzyme has a main subunit of molecular weight of 80, 000 which makes an active aggregate. And at neutral pH range, it has optimum pH for activity and stability. The Km value was determined to be 0.45$\times$10$^{-3}$ M for $o-Nitrophenyl-\beta-Galactoside.$ In any event, it is interesting to sttudy the $\beta-Galactosidase$ of B. bassiana for the mechanism of secretion and conformational structure of enzyme.