• The Korean Journal of Ecology
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• 제21권5_3호
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• pp.695-702
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• 1998

This study was carried out to investigate to determine seasonal variation of dehydrogenase activity, phosphatase activity, adenosine tri-phosphate content and some physicochemical properties, such as soil pH, moisture content, organic matter and several heavy metal concentrations from Apr. 1997 to jan. 1998 in Pinus densiflora and Quercus mongolica forest in Mt. Nam, to explain a relationship between enzyme activity and the soil factors. There were ranges of 4.03-4.65 in soil pH, 18.65-51.09% in moisture content and 6.69-95.95% in orgainc matter. The organic matter content decreased with soil horizon, showing the higher values in Q. mongolica forest. In comparison to the results of Kawngneung site as control area, there were slightly differences due to a development level of forest ecosystem and microbial degradation of organic matter. The heavy metal concentrations showed 32.50-75.55 ${\mu}g/g$ in Cu, 69.33-134.84 ${\mu}g/g$ in Zn, 57.02-150.32 ${\mu}g/g$ in Pb, and 0.36-1.00 ${\mu}g/g$ in Mt. Nam. These values are higher than in Kwangneung site because of long-term exposure to air pollutants from central city. On the other hand, ATP contents in Mt. Nam were lower than in Kawngneung site in relation to soil organic matter, moisture content and relatively high heavy metal concentrations. ATP contents per soil weight was largest in F+H layer and in spring time of other seasons. Dehydrogenase activity as an index of soil microbial activity had a ranges of 170.67-1,221.66 ${\mu}g$ TPF/g that showed lower values than in Kawngneung site. However, phophatase activity had a contray tendency due to P fertilization for a continuous management. Those values increased through spring to a maximum in the summer and fall in autumn. This is basically caused by metabolic state of soil on the biological activity and several and several factors, such as aeration, soil temperature, vegetation and microflora.

• 한국토양비료학회지
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• 제46권6호
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• pp.487-493
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• 2013

The effects of long-term fertilization on soil biological properties and microbial community structure in the plough layer in a rice paddy soil in southern Korea were investigated in relation to the continuous application of chemical fertilizers (NPK), straw based compost (Compost), combination these two (NPK + Compost) for last 40 years. No fertilization plot (Control) was installed for comparison. Though fertilization significantly improved rice productivity over control, the long-term fertilization of NPK and compost combination was more effective on increasing rice productivity and soil nutrient status than single application of compost or chemical fertilizer. All fertilization treatments had shown significant improvement in soil microbial properties, however, continuous compost fertilization markedly increased soil enzyme and microbial activities as compared to sole chemical fertilization. Results of microbial community structure, evaluated by EL-FAME (ester-linked fatty acid methyl esters) method, revealed big difference among Control, NPK, and Compost. However, both Compost and Compost+NPK treatments belonged to the same cluster after statistical analysis. The combined application of chemical fertilizer and organic amendments could be more rational strategy to improve soil nutrient status and promote soil microbial communities than the single chemical fertilizer or compost application.

• 한국지하수토양환경학회지:지하수토양환경
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• 제28권5호
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• pp.68-77
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• 2023

The effect of soil damage on the physicochemical characteristics and activity of the soil microbial community is not well known. This study investigates this relationship by analyzing 11 soil samples collected from various points of soil damage across Gyeonggi-do. Soil damage resulted from forest fires, landslides, and development areas, with their impacts most severe on the topsoil layer (0-30 cm). Dehydrogenase and β-glucosidase activities were notably higher at locations damaged by forest fires compared to other sites. While enzyme activities in soils influenced by landslides and development areas were relatively low, sites with a pollution history exhibited elevated dehydrogenase activity, likely due to past microbial response to the pollution. Additionally, an assessment of carbon substrate usability by soil microorganisms indicated higher substrate availability in areas impacted by forest fires, contrasting with lower availability in landslide and development sites. Statistical analysis revealed a positive correlation between organic content of sand and clay and microbial activity. These findings provide valuable insights into soil damage and associated restoration research, as well as management strategies.

• Journal of Microbiology and Biotechnology
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• 제23권9호
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• pp.1279-1286
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• 2013

Particle size and metal species are important to both soil microbial toxicity and phytotoxicity in the soil ecosystem. The effects of CuO and ZnO nanoparticles (NPs) and microparticles (MPs) on soil microbial toxicity, phytotoxicity, and bioaccumulation in two crops (Cucumis sativus and Zea mays) were estimated in a soil microcosm. In the microcosm system, soil was artificially contaminated with 1,000 mg/kg CuO and ZnO NPs and MPs. After 15 days, we compared the microbial toxicity and phytotoxicity by particle size. In addition, C. sativus and Z. mays were cultivated in soils treated with CuO NPs and ZnO NPs, after which the treatment effects on bioaccumulation were evaluated. NPs were more toxic than MPs to microbes and plants in the soil ecosystem. We found that the soil enzyme activity and plant biomass were inhibited to the greatest extent by CuO NPs. However, in a Biolog test, substrate utilization patterns were more dependent upon metal type than particle size. Another finding indicated that the metal NP uptake amounts of plants depend on the plant species. In the comparison between C. sativus and Z. mays, the accumulation of Cu and Zn by C. sativus was noticeably higher. These findings show that metal oxide NPs may negatively impact soil bacteria and plants. In addition, the accumulation patterns of NPs depend on the plant species.

• 한국작물학회지
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• 제52권3호
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• pp.341-347
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• 2007

Chinese milk vetch (CMV) is a winter legume that is commonly used as cover crop in Korea. Kill date of cover crop for addition into soil affects N content in cover crop and N availability in soil. This study was conducted to evaluate the effect of CMV as green manure cover crop according to kill dates before growing corn without artificial fertilizer. Top of CMV cut three times on 13 April, 27 April, and 11 May were added into soil at a rate of 600 kg per 10a. Sugar content in CMV litter was persistently decreased from mid-April to late-May. The decrease of sugar content might be due to the transformation into starch and/or other storage or structural constituents. The decreased amount of sugars was greater than 12% and the increased amount of starch was less than 0.2%. Concentration of $NH_4^+$ in soil treated by CMV litter cut on May 11 was slightly higher than that in the treatment with early-cut (April 13) CMV, the concentration at 28 and 49 DAT (days after treatment) was higher in the treatment with late-cut CMV litter. Regardless of cut (kill) date of CMV, the phosphatase activity in the treatment of CMV litter was higher compared to the untreated control. Soil dehydrogenase activity was increased steadily by addition of CMV litter implying total microbial activities in the soil were increased. Our results demonstrate that the status of cover crop species at kill date is an important factor influencing soil enzyme activities derived from microorganisms. Therefore, the optimal kill date of cover crop should be examined to improve the efficiency of cover crop as green manure crop regarding the practical sequence in cropping system.

• Journal of Microbiology and Biotechnology
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• 제33권6호
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• pp.760-770
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• 2023

Continuous cropping obstacles have become a serious factor restricting sustainable development in modern agriculture, while companion planting is one of the most common and effective methods for solving this problem. Here, we monitored the effects of companion planting on soil fertility and the microbial community distribution pattern in pepper monoculture and companion plantings. Soil microbial communities were analyzed using high-throughput sequencing technology. Companion plants included garlic (T1), oat (T2), cabbage (T3), celery (T4), and white clover (T5). The results showed that compared with the monoculture system, companion planting significantly increased the activities of soil urease (except for T5) and sucrase, but decreased catalase activity. In addition, T2 significantly improved microbial diversity (Shannon index) while T1 resulted in a decrease of bacterial OTUs and an increase of fungal OTUs. Companion planting also significantly changed soil microbial community structures and compositions. Correlation analysis showed that soil enzyme activities were closely correlated with bacterial and fungal community structures. Moreover, the companion system weakened the complexity of microbial networks. These findings indicated that companion plants can provide nutrition to microbes and weaken the competition among them, which offers a theoretical basis and data for further research into methods for reducing continuous cropping obstacles in agriculture.

• Journal of Microbiology and Biotechnology
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• 제29권6호
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• pp.944-951
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• 2019

Lipases are industrial enzymes that catalyze both triglyceride hydrolysis and ester synthesis. The overexpression of lipase genes is considered one of the best approaches to increase the enzymatic production for industrial applications. Subfamily I.2. lipases require a chaperone or foldase in order to become a fully-activated enzyme. The goal of this research was to isolate, clone, and co-express genes that encode lipase and foldase from Burkholderia territorii GP3, a lipolytic bacterial isolate obtained from Mount Papandayan soil via growth on Soil Extract Rhodamine Agar. Genes that encode for lipase (lipBT) and foldase (lifBT) were successfully cloned from this isolate and co-expressed in the E. coli BL21 background. The highest expression was shown in E. coli BL21 (DE3) pLysS, using pET15b expression vector. LipBT was particulary unique as it showed highest activity with optimum temperature of $80^{\circ}C$ at pH 11.0. The optimum substrate for enzyme activity was $C_{10}$, which is highly stable in methanol solvent. The enzyme was strongly activated by $Ca^{2+}$, $Mg^{2+}$, and strongly inhibited by $Fe^{2+}$ and $Zn^{2+}$. In addition, the enzyme was stable and compatible in non-ionic surfactant, and was strongly incompatible in ionic surfactant.

• 한국자원식물학회지
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• 제21권4호
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• pp.324-328
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• 2008

인삼재배지 180지점으로부터 토양을 채취하여 토양산도, 유기물함량 및 유효인산함량을 측정한 결과 재배년수별 유의한 차이는 나타나지 않았다. 채취한 토양의 메탄올추출액으로 상추종자 발아실험을 실시한 결과 $5{\sim}6$년 재배지의 토양에서 종자발아나 유묘생장을 강하게 억제하는 토양추출액을 선발하였다. 선발된 토양 추출액중 발아와 유묘생장을 억제하였던 추출액은 인삼배양세포의 활력을 최대 90%까지 억제하였으나 전해물질의 누출은 증가하지 않았다. 토양추출액으로 세가지 종류의 항산화 효소 활성을 측정한 결과 superoxide dismutase는 거의 영향을 받지 않았으나, 상추유묘의 생체중억제형 토양추출액을 처리한 인삼배양세포의 peroxidase의 활성이 현저하게 억제되었고, catalase의 활성은 발아억제형 및 생체중억제형 토양추출액 모두에서 유의한 억제를 보였다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2005년도 총회 및 춘계학술발표회
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• pp.171-174
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• 2005

Suspected carcinogen, TCE and PCE, are the most common groundwater pollutants extensively used as a solvent and degreaser. In this study, oxygenases were immobilized in Ca-alginate and chitosan bead. TCE degradation by the immoblized enzyme beads were measured for various size, enzyme addition volume and TCE contact time. The degradation was decreased as increasing the bead size. For overnight , more than 20% of TCE was degraded. The variation of enzyme activity was tested for the repeated use of enzyme beads.

• Forest Science and Technology
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• 제14권4호
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• pp.153-159
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• 2018

Seedlings of Pterocarpus indicus were grown in both well-watered and drought stress conditions in phytotron. Seedlings grown under well-watered and drought stress conditions were exposed to either combined or without ozone of 200 ppb for one month. First, the physiological responses to elevated ozone levels indicated a decreased biomass. The seedlings grown in arid soil and exposed to ozone showed less biomass than those grown in arid soil but not exposed to ozone. Moreover, all the seedlings except the well-watered and unexposed ones showed a significantly lower photosynthetic rate ($P_N$) over time. However, with the accumulation of ozone injuries, the antioxidant enzyme activities increased overall. In the study results, when exposed to ozone, the well-watered seedlings exhibited more antioxidative enzyme activity than did the seedlings grown in arid soil. Generally, P. indicus in arid soil suffered less damage from elevated ozone than did the well-watered plants.