• 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.

• Journal of Ecology and Environment
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• v.33 no.3
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• pp.261-270
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• 2010

Increasing atmospheric $CO_2$ affects the soil carbon cycle by influencing microbial activity and the carbon pool. In this study, the effects of elevated $CO_2$ on extracellular enzyme activities (EEA; ${\beta}$-glucosidase, N-acetylglucosaminidase, aminopeptidase) in salt marsh sediment vegetated with Suaeda japonica were assessed under ambient atmospheric $CO_2$ concentration (380 ppm) or elevated $CO_2$ concentration (760 ppm) conditions. Additionally, the community structure of sulfate-reducing bacteria (SRB) was analyzed via terminal restriction fragments length polymorphism (T-RFLP). Sediment with S. japonica samples were collected from the Hwangsando intertidal flat in May 2005, and placed in small pots (diameter 6 cm, height 10 cm). The pots were incubated for 60 days in a growth chamber under two different $CO_2$ concentration conditions. Sediment samples for all measurements were subdivided into two parts: surface (0-2 cm) and rhizome (4-6 cm) soils. No significant differences were detected in EEA with different $CO_2$ treatments in the surface and rhizome soils. However, the ratio of ${\beta}$-glucosidase activity to N-acetylglucosaminidase activity in rhizome soil was significantly lower (P < 0.01) at 760 ppm $CO_2$ than at 380 ppm $CO_2$, thereby suggesting that the contribution of fungi to the decomposition of soil organic matter might in some cases prove larger than that of bacteria. Community structures of SRB were separated according to different $CO_2$ treatments, suggesting that elevated $CO_2$ may affect the carbon and sulfur cycle in salt marshes.

• Korean Journal of Environmental Agriculture
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• v.33 no.4
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• pp.262-270
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• 2014

BACKGROUND: Coal combustion bottom ash(BA) has high carbon and calcium content, and alkaline pH, which might improve nutrient cycling in soil related to microbial enzyme activities as it is used as soil amendment. However, it contains heavy metals such as copper(Cu), manganese (Mn), and zinc(Zn), which could cause heavy metals accumulation in soil. Compost might play a role that stabilize BA. The objective of this study was to evaluate effect of combined application of BA and compost as soil amendment on heavy metals concentration, enzyme activities, chemical properties, and crop yield in upland soil. METHODS AND RESULTS: BA was applied at the rate of 0, 20, 40, and 80 Mg/ha under different rate of compost application (0 and 30 Mg/ha) in radish (Raphanus sativus var) field. Combined application of BA and compost more improved chemical properties such as pH, EC, OM, total nitrogen, available phosphate, and exchangeable cations of soil than single application of BA. Water soluble Mn and Zn concentration in soil significantly decreased with increasing application rate of BA. Decrease in those metals concentration was accelerated with combined application of BA and compost. Urease and dehydrogenase activities significantly increased with increasing application rate of BA. Phosphotase activities were not affected with single application of BA but increased with combined application of BA and compost. Radish yield was not affected by application rate of BA. CONCLUSION: From the above results, combined application of BA and compost could be used as soil amendment to improve chemical properties and enzyme activities of soil without increase in heavy metal concentration and decrease in crop yield in upland soil.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.3
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• pp.222-229
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• 2009

This study was performed to evaluate effect of different fertilization management practices on soil microbial activities and community structure using soil enzyme activities and PLFA contents in volcanic ash citrus orchard soil. Six experiment plots have differently managed based on the recommended application rate(NPK) of chemical fertilizer and compost for 13 years. Experiment plots were composed of no-fertilization(control), compost only, half amount of NPK with compost (1/2NPK+COM), NPK, NPK with compost(NPK+COM), and 3 times amount of NPK(3NPK). Soil samples collected in early March, May, July, and September 2007. Urease activity was high at NPK+COM in March, May, and September. It was higher in NPK+COM than in NPK. Urease activity decreased according to the order NPK>compost>control in March and May; compost>NPK>control in July and September. Dehydrogenase activity was significantly higher in 1/2NPK+COM($4.3ug\;TPF\;g^{-1}\;24h^{-1}$) than in control($2.4ug\;TPF\;g^{-1}\;24h^{-1}$), May. $\beta$-glucosidase activity was significantly higher in NPK and 1/2NPK+COM than in control, May. In March, Total PLFA contents were higher in NPK+COM($349.2n\;mol\;g^{-1}$) than in 3NPK($228.5n\;mol\;g^{-1}$). And that were higher in 1/2NPK+COM($237.8n\;mol\;g^{-1}$) than in 3NPK($133.1n\;mol\;g^{-1}$), May. Distribution ratio of soil microbial groups by PLFA biomaker were not significantly difference in between seasonal and treatments. Principal component analysis by PLFA profiles showed that microbial community in compost and 3NPK plot were different compared with other treatments in March. But Differences in compost and 3NPK plot were not found in May. Our result showed that the change of microbial community structure affected by fertilization effect and seasonable variation.

• Korean Journal of Food Science and Technology
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• v.26 no.4
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• pp.375-381
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• 1994

A bacterial strain No. KY-126, which produced extracellular cyclodextrin glycosyltransferase(CGTase), was isolated from soil and identified as Bacillus stearothermophilus KY-126. The enzyme was purified by the treatments of ammonium sulfate precipitation, DEAF-Sephadex, Sephadex G-100 column chromatography. The optimal pH and temperature for the enzyme activity were pH 5.5 and $65^{\circ}C$, respectively. And the enzyme was stable at pH values from 6.0 to 11.0 at $55^{\circ}C$ for 30 min and stable up to $60^{\circ}C$ for 30 min.. The enzyme was inhibited by $HgCl_{2}$. The molecular weight of the enzyme was estimated to be 67,000 by using SDS-PAGE. The maximum conversion from starch to cyclodextrin (CD) by CGTase was 43% and obtained at 6 hr reaction and the ratio of ${\alpha}-,\;{\beta}-,\;{\gamma}-$, CD production at this time was 2.9 : 2.1 : 1.0.

• 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.

• Applied Biological Chemistry
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• v.32 no.2
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• pp.109-115
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• 1989

This study was aimed to find out the influence of long-term fertilization for 21 years on soil enzyme activities in the silty clay loam textured normal paddy soil. Total urease activity (TUA) and the microbial urease activity (MUA) were shown to be changed significantly, but the accumulated urease activity (AUA) was similar within trial plots. Especially the MUA of the plots annually applied N.P.K. fertilizers with compost and N.P.K. fertilizers with silicate fertilizer were the highest among plots. The total L-glutaminase activity (TGA) and the accumulated L-glutaminase activity(AGA) were changed significantly among trial plots, but the microbial L-glutaminase activity (MGA) was not. By the simple correlation analysis, it was shown that the TGA and the AGA correlated highly significant to available phosphorus available $SiO_2$ content and pH. Addition of the toluene to the incubation mixture did not markedly affect the activity of phosphatase, but the difference of phosphatase activity among plots was significant. By the simple correlation analysis, it was shown that the phosphatase activity ; correlated highly significant to pH, available $SiO_2$, available phosphorus and exchangeable calcium in soils.

• Applied Biological Chemistry
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• v.41 no.1
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• pp.6-12
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• 1998

To extract insoluble proteins and to improve functional properties of abolished proteins, a protease producing Aspergillus sp. MS-18 was isolated from soil. The enzyme was purified and its enzymological characteristics were investigated. It was found that production of protease reached to the maximum when the wheat brae medium containing, 3% arabinose, 0.5% polypepton, 0.1% $(NH_4)_2SO_4$ and 0.2% magnesium chloride was cultured for 3 days. Protease was purified 16.9 folds after ion exchange chromatography and gel filtration and the specific activity was 340.4 unit/mg. Purified enzyme was confirmed as a single band by the polyacrylamide gel electrophoresis. The molecular weight of protease was estimated to be 30,000. Crystalization form of purified protease was a stick shape with rounding edges. The optimum pH and temperature for the protease activity were 9.0 and $60^{\circ}C$, respectively. The enzyme was stable in pH 7.0-12.0 at $50^{\circ}C$. The activity of purified enzyme was inhibited by $Hg^{2+}$, $Cu^{2+}$, $Zn^{2+}$ and $Pb^{2+}$, whereas it was activited by $Na^+$, $Mg^{2+}$ and $Mn^{2+}$. The activity of the protease was inhibited by the treatment with ethylenediaminetetraacetic acid and phenylmethane sulfonyl fluoride. The result suggests that the purified enzyme is a serine protease with metal ion at active site. Km and Vmax of purified protease were $29.33\;{\mu}mole/L$ and $5.13\;{\mu}g/min$, respectively.

• Korean Journal of Microbiology
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• v.14 no.2
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• pp.65-74
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• 1976

Atternaria sp. was isolated from soil and crude cellulases were prepared from wheat bran culture of the fungus. The activities of the crude enzyme were studied on five different subvstrates and some phsical properties were also examined, crude enzymes were purified by column chromatography on DEAE Sephadex and Sephadex, Isozymes were separated some of which were active specifically on DEAE cellulose and some were primarily active on cellulose and CM-cellulose. The optimal points of pH and temperature for the crude enzyme were varied depending on the substrates ; On cellulose they were at pH 6.0 and 40.deg.C, on CM-cellulose at pH's 4.0 and 6.0 and 60.deg.C, and on DEAW-cellulose at pH 5.0 and 50.deg.C. Two active fractions, F-1 and F-II on Na-CMC was used as substrate the Km values of crude enzyme, F-I and F-II were calculated to be $4{\times}10^{-5}$ , 1.1 * 10$^{-4}$ , and $1.25{\times}10^{-4}mN$ resepctively. The Ki value of $Cu^{++}$ for crude enzyme was$4{\times}^{-4}mN$ , while that of $Nm^{++}$ while in the same concentration of $Mn^{++}$ it reached to 91%. Some 57% activity of F-1 was inhibited in s mN $Cu^{++}$, whereas it was inhibited as much as 81% in the same concentration above the concentration of 0.3 mM with tis activity reaching up to 137% in 2 mM. On the other hand the F-11 was inhibited by the presence of M $n^{++}$ and some 67% activity was inhibited at 2mM.

• Korean Journal of Environment and Ecology
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• v.24 no.4
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• pp.426-435
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• 2010

The present study attempts to compare the soil chemical characteristics and biological activities (i.e. microbial biomass and soil enzyme activities), and litter decomposition rate of Arundinella hirta and Miscanthus sinensis var. purpurascens) collected from serpentine and non-serpentine sites by litter bag techniques at serpentine and non-serpentine field experiment sites over a 9-month period. The serpentine soil showed higher pH and soil alkaliphosphatase activity, and lower soil dehydrogenase and urease activities than the non-serpentine soil. Microbial biomass-N at the serpentine soil was larger than the non-serpentine soil, although the microbial biomass-C and microbial biomass-N represented no significant difference between serpentine and non-serpentine soil. These results suggest that the larger microbial biomass-N caused the lower C/N in serpentine soil. At the end of the experiment, the litter samples of A. hirta and M. sinensis collected from serpentine soil revealed a 39.8% and 38.5% mass loss, and the litter sample from non-serpentine soil also showed a 41.1% and 41.7% mass loss at the serpentine site. On the other hand, at the non-serpentine site, 42.2%, 37.4%, and 46.8%, 44.8% were respectively shown. These results demonstrate that the litter decomposition rate is more intensely affected by the heavy metal content of leaf litter than soil contamination. Moreover, the litter collected from the serpentine soil had a lower C/N, whereas the litter decomposition rate was slower than the litter from the non-serpentine soil, because the heavy metal inhibition activities on the litter decomposition process were more conspicuous than the effect of litter qualities such as C/N ratio or lignin/N. The nutrient element content in the decomposing litter was gradually leached out, but heavy metals and Mg were accumulated in the decaying litter. This phenomenon was conspicuous at the serpentine site during the process of decomposition.