• The Korean Journal of Mycology
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• v.47 no.3
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• pp.259-269
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• 2019

Brown spot and sheath rot of rice are caused by fungal pathogens such as Curvularia lunata, Cochliobolus miyabeanus, and Sarocladium oryzae, and cause losses such as reduced rice yield and quality, which is an enormous problem with serious long-term effects. To search biological control agents of phytopathogenic fungi, five kinds of useful Bacillus-like isolates which are excellent in extracellular enzyme activity and produce siderophore were selected from paddy soil of Sunchang in Korea. The selected isolates were tested for excellent antifungal activity against three of the phytopathogenic fungi that frequently occur in rice, and JSRB 177 strain had the most excellent antifungal activity. Based on the experimental results, JSRB 177 is finally selected as a candidate for biological control and identified to Bacillus subtilis through 16S rRNA sequence analysis. In addition, physiological characteristics of JSRB 177 confirmed by analysis of carbohydrate fermentation patterns and enzyme production ability. Based on the above results, JSRB 177 is expected to be used as a biological control agent for the rice pathogenic fungi. In the future, further studies related to industrialization such as port test and establishment of mass production process are needed.

• Journal of Korea Soil Environment Society
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• v.4 no.1
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• pp.13-23
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• 1999

In this research, 3-hydroxypyridine(2-HP) metabolic ability of starving Arthrobacter crystallopoietes cell and the effect of humic acid on the metabolism of this starving cell were evaluated. 2-HP metabolic ability of exponential phase cell (acclimated cell) was much higher than that of lag phase cell (unacclimated cell) during starvation period. After 3 days of starvation, 2-HP half-life of the acclimated cell was 14 hours and that of the unacclimated cell was 46.5 hours. Humic acid enhanced the stability of 2-HP monooxygenase of starving co]1 and, after 2 days of starvation, the residual activity rate of this enzyme of the microbial cell starved in humic acid solution was 12% while the rate for control condition was 1.5%. After 14 days of starvation, 2-HP half-life for control condition was 43 hours and that for humic acid condition was 1.25 hour.

• Korean Journal of Microbiology
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• v.49 no.4
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• pp.369-376
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• 2013

We isolated the ${\beta}$-glucosidase producing bacteria (BGB) in ginseng root system (rhizosphere soil, rhizoplane, inside of root). Phylogenetic analysis of the 28 BGB based on the 16S rRNA gene sequences, BGB from rhizosphere soil belong to genus Stenotrophomonas (3 strains), Bacillus (1 strain), and Pseudoxanthomonas (1 strain). BGB isolates from rhizoplane were Stenotrophomonas (16 strains), Streptomyces (1 strain) and Microbacterium (1 strain). BGB from inside of root were categorized into Stenotrophomonas (3 strains) and Lysobacter (2 strains). Especially, Stenotrophomonas comprised the largest portion (approximately 90%) of total isolates and Stenotrophomonas was a dominant group of the ${\beta}$-glucosidase producing bacteria. We selected strain 4KR4, which had high ${\beta}$-glucosidase activity (108.17 unit), could transform ginsenoside Rb1 into Rd, Rg3, and Rh2 ginsenosides. In determining its relationship on the basis of 16S rRNA sequence, 4KR4 strain was most closely related to Stenotrophomonas rhizophila e-$p10^T$ (AJ293463) (99.62%). Therefore, on the basis of these polyphasic taxonomic evidence, the ginsenoside Rb1 converting bacteria 4KR4 was identified as Stenotrophomonas sp. 4KR4 (=KACC 17635).

• The Plant Pathology Journal
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• v.25 no.1
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• pp.62-69
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• 2009

In this study, we characterized the bacterial strain KJ2C12 in relation with its biocontrol activity against Phytophthora capsici on pepper, and identified this strain using morphological, physiological, biochemical, fatty acid methyl ester, and 16S rRNA gene sequence analyses. Strain KJ2C12 significantly (P=0.05) reduced both final disease severity and areas under the disease progress curves of 5-week-old pepper plants inoculated with P. capsici compared to buffer-treated controls. As for the production of antibiotics, biofilms, biosurfactant, extracellular enzyme, HCN, and swarming activity, strain KJ2C12 produced an extracellular enzyme with protease activity, but no other productions or swarming activity. However, Escherichia coli produced weak biofilm only. Strain KJ2C12 could colonize pepper roots more effectively in a gnotobiotic system using sterile quartz sand compared to E. coli over 4 weeks after treatments. However, no bacterial populations were detected in 10 mM $MgSO_4$ buffer-treated controls. Strain KJ2C12 produced significantly higher microbial activity than the $MgSO_4$-treated control or E. coli over 4 weeks after treatments. Bacterial strain KJ2C12 was identified as Bacillus luciferensis based on morphological, physiological, and biochemical characteristics as well as FAME and 16S rRNA gene sequence analyses. In addition, these results suggested that B. luciferensis strain KJ2C12 could reduce Phytophthora blight of pepper by protecting infection courts through enhanced effective root colonization with protease production and an increase of soil microbial activity.

• Molecular & Cellular Toxicology
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• v.1 no.3
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• pp.189-195
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• 2005

Industrial development has increase consumption of crude oil and environmental pollution. A large number of microbial lipolytic enzymes have been identified and characterized to date. To development for a new lipase with catalytic activity in degradation of crude oil as a microbial enzyme, Acinetobactor sp. B2 was isolated from soil samples that were contaminated with oil in Daejon area. Acinetobactor sp. B2 showed high resistance up to 10 mg/mL unit to heavy metals such as Ba, Li, Al, Cr, Pb and Mn. Optimal growth condition of Acinetobactor sp. B2 was confirmed $30^{\circ}C$. Lipase was purified from the supernatant by Acinetobactor sp. B2. Its molecular mass was determined to the 60 kDa and the optimal activity was shown at $40^{\circ}C$ and pH 10. The activation energies for the hydrolysis of p-nitrophenyl palmitate were determined to be 2.7 kcal/mol in the temperature range 4 to $37^{\circ}C$. The enzyme was unstable at temperatures higher than $60^{\circ}C$. The Michaelis constant $(K_{m})\;and\;V_{max}$ for p-nitrophenyl palmitate were $21.8{\mu}M\;and\;270.3{\mu}M\;min^{-1}mg\;of\;protein^{-1}$, respectively. The enzyme was strongly inhibited by $Cd{2+},\;Co^{2+},\;Fe^{2+},\;Hg^{2+},\;EDTA$, 2-Mercaptoethalol. From these results, we suggested that lipase purified from Acinetobactor sp. B2 should be able to be used as a new enzyme for degradation of crude oil, one of the environmental contaminants.

• Korean Journal of Organic Agriculture
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• v.30 no.3
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• pp.409-422
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• 2022

Southern blight caused by Sclerotium rolfsii is a serious soilborne disease in economically important crops including pepper. In this study, we conducted a selection of antagonistic bacterial strains and organic materials to biologically control the disease. Out of 39 strains isolated from soils at Jinju in Korea, strain JJ2-01 showed the highest mycelial growth inhibition; garlic oil among various organic materials significantly reduced disease incidence and severity. When a combination of strain JJ2-01 and garlic oil, or each was drenched into the pepper plants, combined treatment and garlic oil significantly suppressed the disease development, however, acid phosphatase activity in garlic oil-treated plants decreased. In the case of combined treatment, the soil activities did not affect by treatment, while soil urease activity was significantly increased by the combined treatment. Therefore, given soil quality and health for sustainable agriculture, the combination of strain JJ2-01 and garlic acid was an effective application for environmental-friendly control of Southern blight in pepper plants.

• Journal of Microbiology and Biotechnology
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• v.21 no.4
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• pp.341-346
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• 2011

To study the effects of salinity-sodicity on bacterial population and enzyme activities, soil samples were collected from the Bay of Yellow Sea, Incheon, South Korea. In the soils nearest to the coastline, pH, electrical conductivity ($EC_e$), sodium adsorption ratio (SAR), and exchangeable sodium percentage (ESP) were greater than the criteria of saline-sodic soil, and soils collected from sites 1.5-2 km away from the coastline were not substantially affected by the intrusion and spray of seawater. Halotolerant bacteria showed similar trends, whereas non-tolerant bacteria and enzymatic activities had opposite trends. Significant positive correlations were found between EC, exchangeable $Na^+$, and pH with SAR and ESP. In contrast, $EC_e$, SAR, ESP, and exchangeable $Na^+$ exhibited significant negative correlations with bacterial populations and enzyme activities. The results of this study indicate that the soil chemical variables related with salinity-sodicity are significantly related with the sampling distance from the coastline and are the key stress factors, which greatly affect microbial and biochemical properties.

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.6
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• pp.169-176
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• 2014

To evaluate bio-cementation of microbial on sands, laboratory test was conducted using acrylic cubic molding boxes ($5cm{\times}5cm{\times}5cm$). It was incubated the microbial, called Bacillus Pasteurii, according to Park et al (2011, 2012). and applied 50ml each specimen. Two type of sand samples used were Jumoonjin sand and common sand (well graded). These sands were molded in acrylic boxes with the relative density of 30 % and 60 % respectively. Microbial were poured onto the samples molded in acrylic boxes and cured at the room temperature and humidity. After 7, 14 and 21days, it was measured the compressive strength, pH, EC, and density and it were observed SEM and XRD to verify the effect of bio-cementation. It was found that bio-cementation was increased a strength of sands and it was appeared that strengths were related to the type of sand and relative density. Therefore it was confirmed the solidification of sands using the bio-cementation by microbial activation and the usefullness of acrylic molding boxes when tests were conducted on the soil of sands.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.2
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• pp.127-134
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• 2017

Bottom ash (BA) has different macro- and micronutrients such as B, Mo, Fe, Ca, and Mg, providing useful resources for plant growth and soil quality. The objective of this study was to evaluate the applicability of artificial top-soil treated with BA in park area as a vegetation base material, especially for turfgrass growth. Collected BA was mixed with peat moss and clay at the ratio of 70:10:20 (w/w). In order to evaluate the park quality and turfgrass growth in park area, the artificial soil was applied with BA along with the control or without BA. Result showed that exchangeable K and P were increased by $11.4mg\;kg^{-1}$ and $163mg\;kg^{-1}$, respectively, compared to the control soil when the artificial soil was treated with BA. Microbial population and enzyme activity (Acid-phosphatase, APA) in artificial soil having BA also increased as 2 times and 10%, respectively, compared to the control soil. Comparing turfgrass growth and yield between general soil and artificial soil, about 2 times higher plant yield (fresh weight) was observed as artificial soil was applied comparing to general soil. Furthermore, nutrient concentration in turfgrass was averaged as 0.440% for $P_2O_5$, 0.456% for CaO, 1.198% for $K_2O$ and 0.188% for MgO that all values are higher than general soil (0.323% for $P_2O_5$, 0.416% for CaO, 0.610% for $K_2O$ and 0.173% for MgO). Application of BA can be useful for vegetation base material in park site.

• Journal of the Korea Organic Resources Recycling Association
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• v.13 no.1
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• pp.79-89
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• 2005

Forest soils were analyzed on their biological and physicochemical properties for the ecological restoration of burnt forest soil using organic wastes and proper microorganisms. Three kinds of soil samples were collected from undamaged soil(US), naturally restoring soil(NS) and artificially restoring soil(AS). All soil samples were sandy soil and acidic soil, ranged pH 5.34~5.78. Moisture content was higher in the soil of NS region. And the others were similar. Total organic matter and soluble sugar were higher at the surface, generally. Heterotrophic soil microbes were abundant at the surface soil of NS and subsoil of AS. Dehydrogenase, cellulase and phosphatase activities were higher at the NS soil. Especially, Dehydrogenase activity as primary index of soil microbial process showed high correlationship with moisture content(r=0.90, P < 0.05).