• Journal of Life Science
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• v.23 no.5
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• pp.676-681
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• 2013

Perchlorate (${ClO_4}^-$) is an emerging contaminant found in surface water and soil/groundwater. Microbial removal of perchlorate is the method of choice since perchlorate-reducing bacteria (PRB) can reduce perchlorate to harmless end-products. A previous study [3] showed experimental evidence of autotrophic perchlorate removal using elemental sulfur granules and activated sludge. The granular sulfur is a relatively inexpensive electron donor, and activated sludge is easily available from a wastewater treatment plant. A batch test was performed in this study to further investigate the effect of various environmental parameters on the perchlorate degradation by sludge microorganisms when elemental sulfur was used as electron donor. Results of the batch test suggest optimum conditions for autotrophic perchlorate degradation by sludge microorganisms. The results also show that sulfur-oxidizing PRB enriched from activated sludge removed perchlorate better than activated sludge. Taken together, this study suggests that autotrophic perchlorate removal using elemental sulfur and activated sludge can be improved by employing optimized environmental conditions and enrichment culture.

• The Korean Journal of Pesticide Science
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• v.15 no.4
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• pp.495-501
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• 2011

Bacterial strains were isolated from forest soils of Halla mountain, Jeju island in Korea. The soil samples were collected at each altitude of 100m from 1,000 m above sea level. Total 398 strains were isolated and tested for their physiological characteristics of antagonistic and proteolytic activities, and auxin production. Among the isolates, 172 strains were selected as antifungal strains showing antagonistic activity against at least one of 8 plant fungal pathogens (Alternaria alternata, Botrytis cinerea, Collectotrichum acutatum, Fusarium oxysporum, Phytophthora capsici, Pythium ultimum and Sclerotinia sclerotiorum). In addition 203 strains for proteolytic activity and 26 strains for auxin production were characterized for further study. Je28-4 (Rhodococcus sp.) were showed 80% of control value against tomato gray mold in vivo. Thus, it is suggested that soil bacteria isolated from forest soils of Halla mountain can be important sources of bioactive compounds for improving plant growth or promising biocontrol agents.

• Korean Journal of Food Science and Technology
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• v.32 no.2
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• pp.410-416
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• 2000

Changes in microflora and enzyme activities of three kinds of kochujang were investigated during 6 months of fermentation. Three different kinds of kochujang were prepared using Aspergillus oryzae, Aspergillus oryzae plus Bacillus licheniformis and Aspergillus oryzae, Bacillus licheniformis plus Saccharomyces rouxii. The pH of kochujang showed a slight decrease during fermentation. The number of mold and bacteria increased up to 30 days of fermentation and then decreased rapidly thereafter and the numbers of yeast increased after 30 days of fermentation. The viable cell counts of anaerobic bacteria increased remarkably up to 30 days of fermentation and then decreased to 60 days of fermentation. The activities of ${\alpha}-$, ${\beta}-\;amylase$ and protease were the highest in kochujang prepared with Aspergillus oryzae plus Bacillus licheniformis.

• Korean Journal of Microbiology
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• v.55 no.2
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• pp.143-148
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• 2019

The synthesis of captopril as an important chiral drug in commerce needs expensive resolution process of racemic mixture. Microorganisms, producing a thermostable esterase that catalyzes the stereo-selective hydrolysis of methyl DL-${\beta}$-acetylthioisobutyrate (DL-ester) to D-${\beta}$-acetylthioisobutyric acid (DAT) were screened from soils. Among the strains tested, strain No CJ-317 and strain No CJ-187 with highest activity were selected as the best DAT producer. The newly isolated microorganisms were identified respectively, as Klebsiella pneumoniae and Pseudomonas putida. The cell activity of esterase from K. pneumoniae CJ-317 and P. putida CJ-187 were showed an optimal reaction activity at $75^{\circ}C$ and $60^{\circ}C$, respectively. Also the cell activity of K. pneumoniae CJ-317 was stable up to $80^{\circ}C$ for 1 h, while that of P. putida CJ-187 was not over $60^{\circ}C$. By varying the concentration of DAT in the reaction mixture, the cell activity of P. putida CJ-187 showed about 55% and 80% of product inhibition in the presence of 2.5% (w/v) and 5.0% of DAT respectively. K. pneumoniae CJ-317 had less product inhibition than P. putida CJ-187 by about 35% and 44% at the same concentrations respectively. The esterase of newly isolated K. pneumoniae CJ-317 could be useful for the stereo-selective hydrolysis of DL-ester to DAT.

• Journal of Life Science
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• v.33 no.10
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• pp.783-790
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• 2023

Modern people have an increased incidence of metabolic diseases due to changed eating habits, and diabetes is considered the most significant metabolic disease. Given that existing diabetes treatments are accompanied by side effects, the aim of this study was to identify traditional natural products that have anti-diabetic activity. The potential anti-diabetic and antioxidant activities of natural products were examined using 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay, α-glucosidase assay, and protein tyrosine phosphatase 1B (PTP1B) inhibition assay. Methanol extracts of Ulmus davidiana var. japonica, Acer tegmentosum branches, Nelumbo nucifera seeds, and Carthamus tinctorius seeds were found to have high anti-diabetic activity and further fractionated with solvents using ethyl acetate and butanol. Consequently, the ethyl acetate fraction of C. tinctorius seeds (MG-11-E) with high α-glucosidase and PTP1B inhibitory activity was selected. MG-11-E was subjected to preparative thin layer chromatography, and fraction #6 showed high α-glucosidase and PTP1B inhibitory activity. Fraction #6 was analyzed and fractionated via high performance liquid chromatography with 50% methanol as the mobile phase, and anti-diabetic activity was observed in the sample that eluted after 4 min as a single peak. The α-glucosidase inhibitory activity exhibited by this sample seemed to be greater than the PTP1B inhibitory activity; thus, it was concluded that a greater anti-diabetic therapeutic effect may be achieved by combining this agent with natural products that inhibit PTP1B activity.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.12
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• pp.1069-1074
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• 2009

This study investigated soil microbial community and growth of Zea mays to compare the toxicity of nano and micro-sized Cu and Zn oxide particles in microcosm system. In the presence of nanoparticles, biomass of Zea mays reduced by 30% compared with micro-sized particles and inhibited growth. Dehydrogenase activity was inhibited by CuO nano although it was increased by ZnO nano particles. According to the Biolog test, the microbial diversity was decreased after exposed to CuO nanoparticles and ZnO microparticles. Therefore, though it is widely recognized that nanoparticles are more harmful than microparticles, we can conclude that the diversity of microbial community does not always influenced by the size of particles of nano and micro.

• KSBB Journal
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• v.21 no.6 s.101
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• pp.428-432
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• 2006

This study investigated the effect of sulfate source on removal efficiency in electrokinetic bioremediation which needs sulfate to degrade contaminants by an applied microorganism. The representative contaminant and the applied microorganism were phenanthrene and Sphingomonas sp. 3Y, respectively. When magnesium sulfate was used, the magnesium ion combined with hydroxyl ion electrically-generated at cathode to cause the decrease of electrolyte pH, and then the microbial activity was inhibited by that. When ammonium sulfate and disodium sulfate were used to solve the pH control problem, the pH values of electrolyte and soil solution were maintained neutrally, and also the high microbial activity was observed. With the former sulfate source, however, ammonium retarded the phenanthrene degradation, and so the removal efficiency decreased to 12.0% rather than 21.8% with magnesium sulfate. On the other hand, the latter improved the removal efficiency to 27.2%. This difference of removal efficiency would be outstanding for an elongated treatment period.

• Korean Journal of Soil Science and Fertilizer
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• v.21 no.4
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• pp.443-449
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• 1988

The effects of rice-straw annual application on nitrogen fixing microbial flora in the soil of paddy fields and their biological activities were investigated. Experiments were performed in both NPK fertilizer applied soil and rice-straw applied soil of Agricultural Station in Aomori-ken, Japan. The following results were obtained. 1. The ARA by phototrophs was significantly increased in both soil plots. From the soil plot in which 300ppm-nitrogen was applied, the increase of ARA began to be seen from three weeks later. On the other hand, 33ppm-nitrogen applied soil plot and non-nitrogen applied soil plot showed the ARA increase from the beginning. The amount of ARA by non-phototrophs was only one-tenth of that by phototrophs. 2. For the first three weeks, the phototrophic bacteria (mainly Rhodopseudomonas) were predominant in both soil plots. Since then, as the ARA rapidly increased, the proliferation of blue-green algae forming heterocysts was remarkably promoted. Such effects were more distinct in the rice-straw annually applied soil plot than in the NPK fertilizer annually applied soil plot. 3. The degree of proliferation of blue-green algae depended on the amount of applied nitrogen. While Anabaena, Nostoc and Cylindrospermum were largely proliferated in the non-nitrogen applied soil plot, Cylindrospermum and Calothrix were in the 33ppm-nitrogen applied soil plot, but Calothrix tended to predominated in the 100ppm-nitrogen applied soil plot.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.696-701
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• 2011

This study was conducted to investigate impacts of soil properties on microbial distribution in Jeonbuk orchard fields. Soil samples were collected from 110 sites cultivated with different fruit plants. The population of aerobic bacteria and fungi and the content of soil microbial biomass carbon (C) were found to increase with increasing silt content in the soils. Different activity of dehydrogenase was not observed among the different textures of soil. Microbial distribution, amount of microbial biomass C, and dehydrogenase activity in the soils were not significantly different among the topographic sites. However, in pear and grape fruit plant fields, coliform group of bacteria was found in relatively higher population, $133.0{\times}10^3\;CFU\;g^{-1}$ and $107.4{\times}10^3\;CFU\;g^{-1}$, respectively. Microbial groups were simplified and their density was reduced with increasing the cultivation periods of fruit plants. The soil microbial distribution was proportionally correlated with some of soil properties such as soil pH, soil organic matter (SOM) content, and exchangeable Mg content; in particular, the population of Bacillus sp. was proportionally correlated with soil pH and exchangeable Mg content. The amounts of microbial biomass C and the dehydrogenase activity in the soils were significantly correlated with the contents of SOM and exchangeable Ca ion (p<0.01).

• Microbiology and Biotechnology Letters
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• v.44 no.2
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• pp.130-139
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• 2016

A bacterial strain, producing an excellent lipolytic enzyme, was isolated from the intestinal tracts of an earthworm (Eisenia fetida). The strain was identified as Aeromonas hydrophila by phenotypic, chemotaxonomic characteristics and 16S ribosomal DNA analysis, and was designated as Aeromona hydrophila PL43. The lipolytic enzyme from A. hydrophila PL43 was purified via 35−45% ammonium sulfate precipitation, DEAE-sepharose fast flow ion-exchange, and sephacryl S-300HR gel filtration chromatography. The yield of the purified enzyme was 3.7% and 2.5% of the total activity of crude extracts with p-nitrophenyl butyrate (pNPB) and p-nitrophenyl palmitate (pNPP) as substrates, respectively. The molecular weight of the purified enzyme was approximately 74 kDa using gel filtration, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and zymography. The optimal activity of purified enzyme was observed at 50℃ and pH 8.0 using pNPB, and 60℃ and pH 8.0 using pNPP. The purified enzyme was stable in the ranges 20− 60℃ and pH 7.0−10.0. The activity of purified enzyme was inhibited by PMSF, pepstatin A, Co²⁺, Cu²⁺, and Fe²⁺, but was recovered by metal chelating of EDTA. The K_m and V_max values of the purified enzyme were 1.07 mM and 7.27 mM/min using pNPB and 1.43 mM and 2.72 mM/min using pNPP, respectively.