• The Korean Journal of Pesticide Science
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• v.9 no.2
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• pp.132-139
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• 2005

New ${\beta}$-methoxyacrylate derivatives 1-4 having thio-enol side chain were prepared and subjected to in vivo screening for fungicidal activity against phytopathogenic fungi and many of them showed good fungicidal activities against especially rice blast and wheat leaf rust at 100 ppm.

• Microbiology and Biotechnology Letters
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• v.24 no.1
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• pp.77-81
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• 1996

During the screening for the antifungal compounds against Phytophthora capsici causing phytophthora blight of red pepper, we isolated a strong active compound, bafilomycin $C_1$, produced by strain 3D3. The producing organism was identified as Streptomyces sp. based on taxonomic studies. The antifungal compound was purified from culture broth by HP-20 column chromatography, ethylacetate extraction, silica gel column chromatography and HPLC, and was identified as bafilomycin $C_1$ by color reaction, UV and $^{1}H$-NMR spectral data analysis. Bafilomycin $C_1$ showed strong antifungal activity against various phytopathogenic fungi.

• Microbiology and Biotechnology Letters
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• v.21 no.1
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• pp.18-22
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• 1993

An assay system by using antibody was adopted to screen the endoinulinase producingfungi due to its high specificity toward endoinulinase, To determine whether the affinity-purified rabbit serum, which were generated against the purified endoinulinase, can react only with the endoinulinase, rocket immunoelectrophoresis was performed. The results showed that the serum specifically reacts with endoinulinase but not with exoinulinase and other proteins in the culture media. Using this polyclonal antibody, a strain from 62 fungal colonies was selected and it secreted an endoinulinase in the culture media to the amount comparable to that of Aspergillus ficuum A Tee 16882 known as a high endoinulinase producer.

• Journal of Mushroom
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• v.10 no.2
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• pp.74-82
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• 2012

Sixty strains of Pleurotus ostreatus, white-rot fungi, were screened for production ability of their lignocellulolytic enzymes to selectively wood degradation. That results were shown that all of screened strains were produced lignocellulolytic enzymes on 2nd screening liquid culture medium. However, cellulase activity of selected six strains of P. ostreatus was low in avicel-yeast-peptone liquid culture medium. In the case of xylan degrading enzyme, No. 6 and No. 38 strains produced a xylanase(above 1.0U/ml) and a 1,4-${\beta}$-xylosidase (above 0.15 U/ml). Examination of the ligninolytic enzyme profiles of selected thirteen strains of the P. ostreatus, in the presence of Remazol Brilliant Blue R(RBBR), were observed that laccase(Lac) activity were earlier reached maximum level(0.8-2.0 U/ml) and then Mn-dependent peroxidase (MnP) were reached maximum level(0.5-1.5 U/ml) in glucose-yeast-peptone(GYP) medium. On the other hand, activity of lignin peroxidase(LiP) was not detected in this medium. I selected the No. 42 strain of P. ostreatus produced high levels of Mn-dependent peroxidase and laccase based on the screening method.

• KSBB Journal
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• v.24 no.2
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• pp.163-169
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• 2009

Lovastatin (also known as Mevinolin, Mevacor, and Monacolin K), an inhibitor of the HMG-CoA reductase produced by Aspergillus terreus and other fungi, is used to reduce serum cholesterol levels in human beings. It is derived biosynthetically from two polyketides. One of these is a nonaketide that undergoes cyclization at a hexahydronaphthalene ring system, and the other is a simple diketide, 2-methylbutyrate. Two primer pairs were designed based on the amino acid sequences of lovastatin polyketide synthase and lovastatin diketide synthase for the PCR screening of lovastatin-producing strains. Among the seven selected strains, SJ-2 evidenced the highest level of lovastatin production in both liquid and solid cultures. Soybeans with SJ-2 were treated via 1 hour of heat shock at $30^{\circ}C$ for the mass production of lovastatin. The heat-treated soybeans were inoculated on rice bran and the koji extract was obtained after 15 days of incubation. It yielded the highest level of lovastatin production among the strains, and also evidenced 75% inhibition activity against HMG-CoA reductase. We developed an efficient PCR screening method for lovastatin-producing strains, using lovastatin biosynthesis genes.

• The Korean Journal of Pesticide Science
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• v.5 no.3
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• pp.26-35
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• 2001

In order to search potent antifungal substances from domestic plants, 40 plants cultivated in Korea were collected. After extracting with methanol (MeOH) and concentrating to dryness, the MeOH extracts were screened for in vivo antifungal activity against six plant diseases at a concentration of $2000{\mu}g/mL$. Fourteen extracts showed disease-controlling activity more than 90% against at least one of the 6 plant diseases tested; eight, seven, and three extracts controlled more than 90% the development of rice blast, tomato late blight, and wheat leaf rust, respectively. However, none of the extracts exhibited in vivo antifungal activity more than 90% against rice sheath blight, tomato gray mold, and barley powdery mildew. From the MeOH extracts of Angelica gigas and A. dahurica showing potent controlling activity against rice blast, 1 and 2 antifungal substances, respectively, were isolated by solvent partitioning and column chromatography. The three compounds were identified to be coumarins, namely, decursin, imperatorin, and isoimperatorin, by mass spectrometry and NMR spectroscopy. They were examined for in vitro and in vivo antifungal activities together with umbelliferone (7-bydroxycournarin) and scopoletin (6-methoxy-7-hydroxycoumarin) containing a free hydroxyl group at position 7 to investigate the structure-activity relationship. In vitro, most of 50% growth inhibitory concentrations ($IC_{50}$) were over $200{\mu}g/mL$, indicating that they have relatively weak antifungal activity. The antifungal activity of decursin and scopoletin, containing cyclic alkoxy groups instead of free hydroxyl group at position 7, was stronger than umbelliferone and scopoletin. Especially, decursin and imperatorin showed potent antifungal activities against Pythium ultimum and Magnaporthe grisea, respectively, with $IC_{50}$ values less than $25{\mu}g/mL$. In vivo, decursin and imperatorin showed potent antifungal activity against rice blast, whereas other coumarins hardly controlled the development of 6 plant diseases tested. These results suggest that the antifungal activity of 7-hydroxycoumarin derivative is substantially increased when the hydroxyl group at position 7 is protected by a stable cyclic alkoxy grouping.

• Toxicological Research
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• v.32 no.1
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• pp.81-87
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• 2016

Aflatoxin B1 (AFB1) is produced by Aspergillus flavus growing in feedstuffs. Early detection of maize contamination by aflatoxigenic fungi is advantageous since aflatoxins exert adverse health effects. In this study, we report the development of an optimized conventional PCR for AFB1 detection and a rapid, sensitive and simple screening Real-time PCR (qPCR) with SYBR Green and two pairs of primers targeting the aflR genes which involved aflatoxin biosynthesis. AFB1 contaminated maize samples were divided into three groups by the toxin concentration. Genomic DNA was extracted from those samples. The target genes for A. flavus were tested by conventional PCR and the PCR products were analyzed by electrophoresis. A conventional PCR was carried out as nested PCR to verify the gene amplicon sizes. PCR-RFLP patterns, obtained with Hinc II and Pvu II enzyme analysis showed the differences to distinguish aflatoxin-producing fungi. However, they are not quantitative and need a separation of the products on gel and their visualization under UV light. On the other hand, qPCR facilitates the monitoring of the reaction as it progresses. It does not require post-PCR handling, which reduces the risk of cross-contamination and handling errors. It results in a much faster throughout. We found that the optimal primer annealing temperature was $65^{\circ}C$. The optimized template and primer concentration were $1.5{\mu}L\;(50ng/{\mu}L)$ and $3{\mu}L\;(10{\mu}M/{\mu}L)$ respectively. SYBR Green qPCR of four genes demonstrated amplification curves and melting peaks for tub1, afIM, afIR, and afID genes are at $88.0^{\circ}C$, $87.5^{\circ}C$, $83.5^{\circ}C$, and $89.5^{\circ}C$ respectively. Consequently, it was found that the four primers had elevated annealing temperatures, nevertheless it is desirable since it enhances the DNA binding specificity of the dye. New qPCR protocol could be employed for the determination of aflatoxin content in feedstuff samples.

• Microbiology and Biotechnology Letters
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• v.38 no.4
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• pp.373-378
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• 2010

Studies on standardization and quality upgrade of nuruk which is a basic component in brewing are required to increase the quality level of Korean traditional rice wines and to develop the technology for practical use of it. It is important to isolate best strains, to improve the properties and effectively preserve them for brewing industry. In this study, 16 commercial nuruk samples were obtained from the commercial markets located in Chungcheong areas in Korea. 174 fungal strains were isolated from the samples on DG18 medium using a dilution plating method and then screened for enzyme activity and acid production. The active strains were identified based on the morphological characteristics and ITS sequence analysis. Out of 174 strains, 12 strains showed high amylase activity. Especially, Rhizopus sp. CN084, CN174, Aspergillus sp. CN161 and Mycocladus sp. CN042 showed high saccharogenic power and dextrinogenic enzyme activity on cooked wheat bran medium. On the other hand, Aspergillus sp. CN010, CN161, Rhizopus sp. CN105, CN168 and Rhizomucor sp. CN088 produced high acid production on the same medium. Our results showed that the active strains may be used as microbial sources for nuruk starter with good quality in brewing.

• Asian Journal of Turfgrass Science
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• v.24 no.2
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• pp.176-181
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• 2010

Brown patch (Rhizoctonia solani AG1-1), dollar spot (Sclerotinia homoeocarpa), pythium blight (Pythium spp.), anthracnose (Colletotrichum graminicola), yellow patch (Rhizoctonia cerealis) and Zoysia patch (Rhizoctonia solani AG2-2) are the major turfgrasses diseases in Korea. In this study, 23 medicinal plant extracts were tested for antifungal activities against turfgrass pathogenic fungi. In paper disk diffusion method, 12 medicinal plant extracts, including Sophora flavescens, showed antifungal activity. Also, in the test of antifungal activity on media contained the extracts of S. flavescens, Curcuma longa, Rheum undulatum, Coptis chinensis and Asiasarum sieboldi showed above 80% inhibitory effects on the mycelial growth in 110 mg/10 ml concentration of the extracts. S. flavescens, in particularly, showed antifungal activity against the six turfgrass pathogenic fungi. The inhibition rate of S. homoeocarpa was 100% in 10 mg/10 ml, 5 mg/10 ml and 2 mg/10 ml concentrations of C. longa extract. In case of Pythium spp., the extracts of S. flavescens, R. undulatum and C. chinensis showed 100 % inhibition rate on the test media.

• Microbiology and Biotechnology Letters
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• v.49 no.3
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• pp.391-402
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• 2021

Earthworms play an important role in soil fertilization, interacting continually with microorganisms. This study aims to demonstrate the existence of beneficial microorganisms living in the earthworm's immune system, the coelomic fluid. To achieve this goal, a molecular identification technique was performed, using cytochrome c oxidase I (COI) barcoding to identify abundant endogenic earthworms inhabiting the temperate zone of Rabat, Morocco. Then, 16S rDNA and ITS sequencing techniques were adopted for bacteria and fungi, respectively. Biochemical analysis, showed the ability of bacteria to produce characteristic enzymes and utilize substrates. Qualitative screening of plant growth-promoting traits, including nitrogen fixation, phosphate and potassium solubilization, and indole acetic acid (IAA) production, was also performed. The result of mitochondrial COI barcoding allowed the identification of the earthworm species Aporrectodea molleri. Phenotypic and genotypic studies of the sixteen isolated bacteria and the two isolated fungi showed that they belong to the Pseudomonas, Aeromonas, Bacillus, Buttiauxella, Enterobacter, Pantoea, and Raoultella, and the Penicillium genera, respectively. Most of the isolated bacteria in the coelomic fluid showed the ability to produce β-glucosidase, β-glucosaminidase, Glutamyl-β-naphthylamidase, and aminopeptidase enzymes, utilizing substrates like aliphatic thiol, sorbitol, and fatty acid ester. Furthermore, three bacteria were able to fix nitrogen, solubilize phosphate and potassium, and produce IAA. This initial study demonstrated that despite the immune property of earthworms' coelomic fluid, it harbors beneficial microorganisms. Thus, the presence of resistant microorganisms in the earthworm's immune system highlights a possible selection process at the coelomic fluid level.