• Mycobiology
• /
• 제30권1호
• /
• pp.31-36
• /
• 2002

Soil bacteria were screened for the ability to control cucumber anthracnose caused by Colletotrichum orbiculare through induced systemic resistance(ISR). Sixty-four bacterial strains having in vitro antifungal activity were used for selecting ISR-inducing strains in cucumber. Cucumber seeds(cv. Baeknokdadagi) were sown in potting mixtures incorporated with the soil bacteria, at a rate of ca. $10^8$ cells per gram of the mixture. Two week-old plants were then transplanted into the steam-sterilized soil. Three leaf-stage plants were inoculated with a conidial suspension($5{\times}10^5$ conidia/ml) of C. orbiculare. Diseased leaf area(%) and number of lesions per $cm^2$ leaf were evaluated on third leaves of the plants, $5{\sim}6$ days after inoculation. Among 64 strains tested, nine strains, GC-B19, GC-B35, GK-B18, MM-B22, PK-B14, RC-B41, RC-B64, RC-B65, and RC-B77 significantly(P=0.05) reduced anthracnose disease compared to the untreated control. In contrast, some bacterial strains promoted susceptibility of cucumber to the disease. From the repeated experiments using the nine bacterial strains, GC-B19, MM-B22, PK-B14, and RC-B65 significantly(P=0.05) reduced both diseased leaf area(%) and number of lesions per $cm^2$ leaf in at lease one experiment. These strains with control efficacy of $37{\sim}80%$ were determined to be effective ISR-inducing strains.

• 한국환경과학회지
• /
• 제28권8호
• /
• pp.701-707
• /
• 2019

Highland farming is agriculture that takes place 400 m above sea level and typically involves both low temperatures and long sunshine hours. Most highland Chinese cabbages are harvested in the Gangwon province. The Ubiquitous Sensor Network (USN) has been deployed to observe Chinese cabbages growth because of the lack of installed weather stations in the highlands. Five representative Chinese cabbage cultivation spots were selected for USN and meteorological data collection between 2015 and 2017. The purpose of this study is to develop a weight prediction model for Chinese cabbages using the meteorological and growth data that were collected one week prior. Both a regression and random forest model were considered for this study, with the regression assumptions being satisfied. The Root Mean Square Error (RMSE) was used to evaluate the predictive performance of the models. The variables influencing the weight of cabbage were the number of cabbage leaves, wind speed, precipitation and soil electrical conductivity in the regression model. In the random forest model, cabbage width, the number of cabbage leaves, soil temperature, precipitation, temperature, soil moisture at a depth of 30 cm, cabbage leaf width, soil electrical conductivity, humidity, and cabbage leaf length were screened. The RMSE of the random forest model was 265.478, a value that was relatively lower than that of the regression model (404.493); this is because the random forest model could explain nonlinearity.

• Mycobiology
• /
• 제37권1호
• /
• pp.53-61
• /
• 2009

The process of biodegradation in lingo-cellulosic materials is critically relevant to biospheric carbon. The study of this natural process has largely involved laboratory investigations, focused primarily on the biodegradation and recycling of agricultural by-products, generally using basidiomycetes species. In order to collect super white rot fungi and evaluate its ability to degrade lingo-cellulosic material, 35 fungal strains, collected from forests, humus soil, livestock manure, and dead trees, were screened for enzyme activities and their potential to decolorize the commercially used Poly-R 478 dye. In the laccase enzymatic analysis chemical test, 33 white rot fungi and 2 brown rot fungi were identified. The degradation ability of polycyclic aromatic hydrocarbons (PAHs) according to the utilized environmental conditions was higher in the mushrooms grown in dead trees and fallen leaves than in the mushrooms grown in humus soil and livestock manure. Using Poly-R 478 dye to assess the PAH-degradation activity of the identified strains, four strains, including Agrocybe pediades, were selected. The activities of laccase, MnP, and Lip of the four strains with PAH-degrading ability were highest in Pleurotus incarnates. 87 fungal strains, collected from forests, humus soil, livestock manure, and dead trees, were screened for enzyme activities and their potential to decolorize the commercially used Poly-R 478 dye on solid media. Using Poly-R 478 dye to assess the PAHdegrading activity of the identified strains, it was determined that MKACC 51632 and 52492 strains evidenced superior activity in static and shaken liquid cultures. Subsequent screening on plates containing the polymeric dye poly R-478, the decolorization of which is correlated with lignin degradation, resulted in the selection of a strain of Coriolus versicolor, MKACC52492, for further study, primarily due to its rapid growth rate and profound ability to decolorize poly R-478 on solid media. Considering our findings using Poly-R 478 dye to evaluate the PAH-degrading activity of the identified strains, Coriolus versicolor, MKACC 52492 was selected as a favorable strain. Coriolus versicolor, which was collected from Mt. Yeogi in Suwon, was studied for the production of the lignin-modifying enzymes laccase, manganese-dependent peroxidase (MnP), and lignin peroxidase (LiP).

• 한국미생물·생명공학회지
• /
• 제30권3호
• /
• pp.287-292
• /
• 2002

본 연구에서는 경안천 유역에 있는 주유소 오염토양으로부터 대표적인 아조계 염료 congo-red분해능이 우수한 토양 방선균, SMA-2를 분리 선별하고, SMA-2의 배양조건을 최적화하여 2,4-dichlorophenol의 산화에 관여하는 actinomycetes lignin peroxidase(ALiP)의 활성도에 대한 특성을 규명하였다. 기존에 보고된 방선균 유래 ALiP와는 달리, SMA-2유래 ALiP효소는 pH6에서 최고의 활성을 보였으며, 2,4-DCP와 $H_2$$O_2$에 대한 Km값이 각각 0.21mM과 8.5mM로 측정되었다. 또한 최적화된 배지에서 성장한 SMA-2의 배양액은 2,4-dichlorophenol 뿐만 아니라 2-chlorophenol, 2,4,6-trichlorophenol, 2,6-dichlorophenol, phenol, 4-chloropheno떼 대해서도 산화능을 보임으로써, 토양 방선균을 이용한 염화 페놀계 화합물이 포함된 오염 토양의 생복원 가능성을 제시하였다.

• Journal of Microbiology and Biotechnology
• /
• 제18권12호
• /
• pp.1966-1974
• /
• 2008

A typical tropical soil from the northeast of Brazil, where an important terrestrial oil field is located, was accidentally contaminated with a mixture of oil and saline production water. To study the bioremediation potential in this area, molecular methods based on PCR-DGGE were used to determine the diversity of the bacterial communities in bulk and in contaminated soils. Bacterial fingerprints revealed that the bacterial communities were affected by the presence of the mixture of oil and production water, and different profiles were observed when the contaminated soils were compared with the control. Halotolerant strains capable of degrading crude oil were also isolated from enrichment cultures obtained from the contaminated soil samples. Twenty-two strains showing these features were characterized genetically by amplified ribosomal DNA restriction analysis (ARDRA) and phenotypically by their colonial morphology and tolerance to high NaCl concentrations. Fifteen ARDRA groups were formed. Selected strains were analyzed by 16S rDNA sequencing, and Actinobacteria was identified as the main group found. Strains were also tested for their growth capability in the presence of different oil derivatives (hexane, dodecane, hexadecane, diesel, gasoline, toluene, naphthalene, o-xylene, and p-xylene) and different degradation profiles were observed. PCR products were obtained from 12 of the 15 ARDRA representatives when they were screened for the presence of the alkane hydroxylase gene (alkB). Members of the genera Rhodococcus and Gordonia were identified as predominant in the soil studied. These genera are usually implicated in oil degradation processes and, as such, the potential for bioremediation in this area can be considered as feasible.

• Journal of Microbiology and Biotechnology
• /
• 제15권5호
• /
• pp.1067-1072
• /
• 2005

A metagenomic library was constructed using a fosmid vector, and total genomic DNA was extracted directly from soil at Cisolok (hot spring area, Indonesia). This library was composed of 10,214 clones and screened for lipolytic enzyme on tributyrin agar plates. An esterase gene (estMa) was subcloned and sequenced from a positive lipolytic active clone. Esterase EstMa was encoded by a 954-bp open reading frame and showed low ($11-33\%$) amino acid similarity to known esterases. The amino acid sequence analysis demonstrated that the enzyme is a new member of lipolytic enzyme family VI. The estMa gene encodes a preprotein of 317 amino acids with a predicted molecular mass of 34,799 Da. The purified enzyme exhibited optimal activity at $50^{\circ}C$ and pH 6.5. The $K_m,\;and\;V_{max}$ values of EstMa for the hydrolysis of p-nitrophenyl valerate were $45.3\;{\mu}M$ and 4.45 U/mg, respectively.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2010년도 춘계 학술발표회
• /
• pp.1032-1039
• /
• 2010

Based on the proven feasibility of bottom ash and tire shred-soil mixtures as lightweight fill materials, tire shred-bottom ash mixtures were suggested as a new lightweight fill material to replace the conventional construction material with bottom ash. Therefore, we carried out the laboratory test, field compaction test and performance test of large scale embankment in order to evaluate their suitability for the use of lightweight fill materials in the before studies. We could verified that the ash, tire-shred and the mixture are able to be the useful materials as light fill materials. In this study, we built real scale embankment with RBA(Reclamated Bottom Ash), TRBA(Tire shred-Reclamated Bottom Ash mixture), WS(Weathered Soil), BA(Bottom Ash screened by 5mm sieve) for monitoring the behavior such as settlement, lateral displacement and water content change. Furthermore, we are examining the ground water quality in the surrounding area of the test embankment.

• The Plant Pathology Journal
• /
• 제29권4호
• /
• pp.418-426
• /
• 2013

Pseudomonas isolates from different crop plants were screened for in vitro growth inhibition of Phytophthora capsici and production of biosurfactant. Two in vivo experiments were performed to determine the efficacy of selected Pseudomonas strains against Phytophthora blight of pepper by comparing two fungicide treatments [acibenzolar-S-methyl (ASM) and ASM + mefenoxam]. Bacterial isolates were applied by soil drenching ($1{\times}10^9$ cells/ml), ASM ($0.1{\mu}g$ a.i./ml) and ASM + mefenoxam (0.2 mg product/ml) were applied by foliar spraying, and P. capsici inoculum was incorporated into the pot soil three days after treatments. In the first experiment, four Pseudomonas strains resulted in significant reduction from 48.4 to 61.3% in Phytophthora blight severity. In the second experiment, bacterial treatments combining with olive oil (5 mL per plant) significantly enhanced biological control activity, resulting in a reduction of disease level ranging from 56.8 to 81.1%. ASM + mefenoxam was the most effective treatment while ASM alone was less effective in both bioassays. These results indicate that our Pseudomonas fluorescens strains (6L10, 6ba6 and 3ss9) that have biosurfactant-producing abilities are effective against P. capsici on pepper, and enhanced disease suppression could be achieved when they were used in combination with olive oil.

• Journal of Microbiology and Biotechnology
• /
• 제23권6호
• /
• pp.850-855
• /
• 2013

Finding new antimicrobial activities by functional metagenomics has been shown to depend on the heterologous host used to express the foreign DNA. Therefore, efforts are devoted to developing new tools for constructing metagenomic libraries in shuttle vectors replicatable in phylogenetically distinct hosts. Here we evaluated the use of the Escherichia coli-Bacillus subtilis shuttle vector pHT01 to construct a forest-soil metagenomic library. This library was screened in both hosts for antimicrobial activities against four opportunistic bacteria: Proteus vulgaris, Bacillus cereus, Staphylococcus epidermidis, and Micrococcus luteus. A new antibacterial activity against B. cereus was found upon screening in B. subtilis. The new antimicrobial agent, sensitive to proteinase K, was not active when the corresponding DNA fragment was expressed in E. coli. Our results validate the use of pHT01 as a shuttle vector and B. subtilis as a host to isolate new activities by functional metagenomics.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제20권2호
• /
• pp.41-46
• /
• 2015

The drag of the excess charge in an electrical double layer at the solid fluid interface due to water flow induces the streaming current, i.e., the streaming potential (SP). Here we introduce a sandbox experiment to study this hydroelectric coupling in case of a tracer test. An acrylic tank was filled up with homogeneous sand as a sand aquifer, and the upstream and downstream reservoirs were connected to the sand aquifer to control the hydraulic gradient. Under a steady-state water flow condition, a tracer test was performed in the sandbox with the help of peristaltic pump, and tracer samples were collected from the same interval of five screened wells in the sandbox. During the tracer test, SP signals resulting from the distribution of 20 nonpolarizable electrodes were measured at the top of the tank by a multichannel meter. The results showed that there were changes in the observed SP after injection of tracer, which indicated that the SP was likely to be related to the solute transport.