• Journal of Korea Foresty Energy
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• v.19 no.1
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• pp.49-60
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• 2000

The traditional Korea medical book already recorded various biological activities of the Korean mistletoes. The objective of this study was examine antifungal activities of MeOH extract from the Korean mistletoe through column chromatography on three fungi, such as Tyromyces palustris Endothia nitschkei and Trichophyton rubrum. No mistletoes had anti-fungal activity against T. palusties. Extracts of V. album var. coloratum showed the highest hyphal growth-inhibitory activity against E. nitschkei and leaf extract of this species had higher activity than twig extract. Further fractionation of most active fraction and following antifungal assay showed that its anti-fungal activity might be caused by synergism if its components. It was suggested that Viscum album var. coloratum shows significantly antifungal activities against E. nitschkei and T. rubrum. Further examination is needed to find out more exact active compounds.

• The Korean Journal of Mycology
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• v.41 no.3
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• pp.197-199
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• 2013

The sclerotium rot of corn (Zea mays L.) occurred sporadically at the experimental field of Gyeongsangnam-do Agricultural Research and Extension Services in July 2011. The infected stems were water-soaked, wilted, and finally led to the death of the whole plants. White mycelial mats were spread over lesions, and then sclerotia were formed on stem and near soil line. The sclerotia were globoid in shape, white to brown in color and 1-3 mm in size. The hyphal width was $4-8{\mu}m$. The optimum temperature for mycelial growth and sclerotia formation on PDA was 30 on PDA. The typical clamp connections were observed in the hyphae of the fungus grown on PDA. On the basis of mycological characteristics and pathogenicity to host plants, this fungus was identified as Sclerotium rolfsii Saccardo. This is the first report of sclerotium rot on corn caused by S. rolfsii in Korea.

• Journal of Microbiology and Biotechnology
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• v.22 no.10
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• pp.1359-1366
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• 2012

A strain of Streptomyces cavourensis subsp. cavourensis (coded as SY224) antagonistic to Colletotrichum gloeosporioides infecting pepper plants was isolated. SY224 produced lytic enzymes such as chitinase, ${\beta}$-1,3-glucanase, lipase, and protease in respective assays. To examine for antifungal activity, the treatments amended with the nonsterilized supernatant resulted in the highest growth inhibition rate of about 92.9% and 87.4% at concentrations of 30% and 10%, respectively. However, the sterilized treatments (autoclaved or chloroform treated) gave a lowered but significant inhibitory effect of about 63.4% and 62.6% for the 10% supernatant concentration, and 75.2% and 74.8% for the of 30% supernatant concentration in the PDA agar medium, respectively, indicative of the role of a non-protein, heat stable compound on the overall effect. This antifungal compound, which inhibited spore germination and altered hyphal morphology, was extracted by EtOAc and purified by ODS, silica gel, Sephadex LH-20 column, and HPLC, where an active fraction was confirmed to be 2-furancarboxaldehyde by GS-CI MS techniques. These results suggested that SY224 had a high potential in the biocontrol of anthracnose in pepper, mainly due to a combined effect of lytic enzymes and a non-protein, heat-stable antifungal compound, 2-furancarboxaldehyde.

• Research in Plant Disease
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• v.11 no.1
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• pp.85-87
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• 2005

In July 2003, a destructive stem rot occurred sporadically in an exhibition farm on Aster glehni of Hamyanggun, Gyeongsangnam-do Agricultural Research and Extension Services, Korea. The typical symptoms of the disease were water-soaking, stem rot, wilt or blight. The infected plants were mostly died. White mycelial mats were spread over lesions and sclerotia were formed on stems and near soil line. The sclerotia were globoid or irregular in shape, 1~3 mm in size, and white to brown in color. The optimum temperature for fungal growth was about 30oC. Clamp connections were observed in the hyphae of the fungus grown on potato dextrose agar, and hyphal diameter was 3~8 ${\mu}m$. On the basis of mycological characteristics and test of pathogenicity to host plants, the fungus was identified as Sclerotium rolfsii. This is the first report on the stem rot of Aster glehni caused by S. rolfsii in Korea.

• Research in Plant Disease
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• v.9 no.1
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• pp.25-27
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• 2003

In 2002, a stem rot disease was found on Pansy (Viola tricolor) in several road-side flower beds in Jinju City, Gyeongnam province, Korea. The typical symptoms of the disease were stem rot, crown rot, wilt or blight. Upper parts of the infected stems were mostly blighted. White mycelial mats were spread over lesions and the sclerotia were farmed on the stems near soil line. The sclerotia was globoid or irregular in shape, 1.3~4.2 mm in size, and brown in color, The optimum temperature for fungal growth was about 3$0^{\circ}C$. The typical clamp connections were found in the hyphae of the fungus grown on PDA, and hyphal diameter was 3.9~10.4 ${\mu}{\textrm}{m}$. On the basis of mycological characteristics and pathogenecity test on host plants, the fungus was identified as Sclerotium rolfsii. This is the first report on the stem rot of Viola tricolor caused by Sclerotium rolfsii in Korea.

• Research in Plant Disease
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• v.18 no.1
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• pp.54-56
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• 2012

Sclerotium rot of sponge gourd occurred at the experimental field of Gyeongsangnam-do Agricultural Research and Extension Services in August 2010. The infected fruits showed water-soaked and rot symptoms. White mycelial mats spread over lesions, and then sclerotia were formed on fruit and near soil line. The sclerotia were globoid in shape, 1-3 mm in size and white to brown in color. The optimum temperature for mycelial growth and sclerotia formation on PDA was $30^{\circ}C$ and the hyphal width was 4-8 ${\mu}m$. The typical clamp connections were observed in the hyphae of the fungus grown on PDA. On the basis of mycological characteristics, ITS rDNA sequence analysis, and pathogenicity to host plants, this fungus was identified as Sclerotium rolfsii Saccardo. This is the first report of sclerotium rot on sponge gourd caused by S. rolfsii in Korea.

• Korean Journal Plant Pathology
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• v.10 no.1
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• pp.54-60
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• 1994

Incidence of Rhizoctonia blight ranged from 22.2% to 100% in the golf courses at six geographical locations in Korea from 1989 to 1993. Rhizoctonia blight occurred more severly in southern area than in northern area. Fifty seven isolates of Rhizoctonia solani obtained from diseased parts of zoysiagrasses were grouped to AG2-2 by anastomosis test. Pathogenicity testes revealed that this pathogen was strongly pathogenic to Korean lawngrasses(Zoysia japonica, Z. matrella, Z. tenuifolia), but not pathogenic to creeping bentgrass(Agrostis palustris), bermuldagrass(Cynodon dactylon), Kentucky bluegrass(Poa pratensis), perennial ryegrass(Lolium prenne), and creeping red fescue(Festuca rubra subsp. rubra L.). The isolation frequency of R. solani AG2-2 fro sheaths of the infected plants was the highest by 91.67%, and that from stolons and roots was 11.13% and 5.63% respectively. The pathogen was not isolated from the leaves. Population density of R. solani in the lawn of large circular patch was highest on surface soils down to 1 cm deep with the value of 4.9$\times$104 (CFU/g soil), but below 1 cm population density decreased sharply down to 0.8~9.8$\times$103 (CFU/g soil). Horizontal distribution of propagules in turfgrass soil was higher in the margin than in center of patch, where the number of propagules was similar to these of healthy looking soils close to the margin of diseased patch. The meteorological factors influencing the outbreak of the disease were temperature, the number of rainy days and precipitation. Optimum temperature for disease development of Rhizoctonia blight in field was 20~22$^{\circ}C$, and that for hyphal growth of R. solani AG2-2 in vitro was 25~3$0^{\circ}C$. In Pusan area, Rhizoctonia blight first occurred in late April and rapidly developed in late June. The disease slightly decreased during July to August and developed again in late September in 1993. The monthly disease progress in Pusan area was similar to that in Kyeonggi province.

• Journal of Microbiology and Biotechnology
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• v.31 no.6
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• pp.890-901
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• 2021

The 11α-hydroxylation of canrenone can be catalyzed by Aspergillus ochraceus in bioreactors, where the geometry of the impeller greatly influences the biotransformation. In this study, the effects of the blade number and impeller diameter of a Rushton turbine on the 11α-hydroxylation of canrenone were considered. The results of fermentation experiments using a 50 mm four-blade impeller showed that 3.40% and 11.43% increases in the conversion ratio were achieved by increasing the blade number and impeller diameter, respectively. However, with an impeller diameter of 60 mm, the conversion ratio with a six-blade impeller was 14.42% lower than that with a four-blade impeller. Data from cold model experiments with a large-diameter six-blade impeller indicated that the serious leakage of inclusions and a 22.08% enzyme activity retention led to a low conversion ratio. Numerical simulations suggested that there was good gas distribution and high fluid flow velocity when the fluid was stirred by large-diameter impellers, resulting in a high dissolved oxygen content and good bulk circulation, which positively affected hyphal growth and metabolism. However, a large-diameter six-blade impeller created overly high shear compared to a large-diameter four-blade impeller, thereby decreasing the conversion ratio. The average shear rates of the former and latter cases were 43.25 s^-1 and 35.31 s^-1, respectively. We therefore concluded that appropriate shear should be applied in the 11α-hydroxylation of canrenone. Overall, this study provides basic data for the scaled-up production of 11α-hydroxycanrenone.

• Research in Plant Disease
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• v.27 no.2
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• pp.66-69
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• 2021

In 2020, a brown felt was observed on persimmon (Diospyros kaki) in persimmon orchards, Sangju, Korea. The symptom on persimmon was white to grey mycelial mats on some areas of the branches. Each mat progressively expanded until the mats coalesced to occupy larger areas and finally girdled the branches. The disease branches were covered with brown-colored mold, consisting of hyphal mats of the pathogen. Optimum temperature for mycelial growth was 30℃. On the basis of mycological characteristics, pathogenicity test, and molecular analysis with complete internal transcribed spacer rDNA region, the causal fungus was identified as Septobasidium sp. This is the first report of brown felt caused by Septobasidium sp. on persimmon in Korea.

• Journal of the Korean Wood Science and Technology
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• v.30 no.1
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• pp.48-55
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• 2002

The essential oils were extracted from the needles of several softwood tree species, Pinus densiflora, Pinus koraiensis, Chamaecyparis obtusa and Chamaecyparis pisifera to investigate their biological activities. The antifungal activity by hyphal growth inhibition method was determined by three wood rot fungi, one mouldous fungi, and three tree pathogenic fungi and the antibacterial activity by paper disc method and turbidiometric method by three gram positive bacteria and one gram negative bacteria, Escherichia coli, were also tested. Antifungal activity was the best in the essential oil from C. obtusa, and the following was resulted in order of P. densiflora and P. koraiensis. The essential oil from P. densiflora showed higher antifungal activity against wood rot fungi than that from P. koraiensis while the result was contrary against tree pathogenic fungi. However, the antibacterial activity was the best in the essential oil from P. densiflora, and the following was in order of C. obtusa and P. koraiensis. From these results, the variation of biological activity seemed to be due to the chemical composition of essential oils.