• 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.

• The Plant Pathology Journal
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• v.37 no.6
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• pp.533-542
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• 2021

Chitosan has been considered an environmental-friendly polymer. However, its use in agriculture has not been extended yet due to its relatively low solubility in water. N-Methylene phosphonic chitosan (NMPC) is a water-soluble derivative prepared by adding a phosphonic group to chitosan. This study demonstrates that NMPC has a fungicidal effect on the phytopathogenic fungus Fusarium solani f. sp. eumartii (F. eumartii) judged by the inhibition of F. eumartti mycelial growth and spore germination. NMPC affected fungal membrane permeability, reactive oxygen species production, and cell death. Also, this chitosan-derivative exerted antifungal effects against two other phytopathogens, Botrytis cinerea, and Phytophthora infestans. NMPC did not affect tomato cell viability at the same doses applied to these phytopathogens to exert fungicide action. In addition to water solubility, the selective biological cytotoxicity of NMPC adds value in its application as an antimicrobial agent in agriculture.

• Journal of Microbiology and Biotechnology
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• v.33 no.5
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• pp.607-620
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• 2023

The biocontrol approach using beneficial microorganisms to control crop diseases is becoming an essential alternative to chemical fungicides. Therefore, new and efficient biocontrol agents (BCA) are needed. In this study, a rhizospheric actinomycete isolate showed unique and promising antagonistic activity against three of the most common phytopathogenic fungi, Fusarium oxysporum MH105, Rhizoctonia solani To18, and Alternaria brassicicola CBS107. Identification of the antagonistic strain, which was performed according to spore morphology and cell wall chemotype, suggested that it belongs to the Nocardiopsaceae. Furthermore, cultural, physiological, and biochemical characteristics, together with phylogenetic analysis of the 16S rRNA gene (OP869859.1), indicated the identity of this strain to Nocardiopsis alba. The cell-free filtrate (CFF) of the strain was evaluated for its antifungal potency, and the resultant inhibition zone diameters ranged from 17.0 ± 0.92 to 19.5 ± 0.28 mm for the tested fungal species. Additionally, the CFF was evaluated in vitro to control Fusarium wilt disease in Vicia faba using the spraying method under greenhouse conditions, and the results showed marked differences in virulence between the control and treatment plants, indicating the biocontrol efficacy of this actinomycete. A promising plant-growth promoting (PGP) ability in seed germination and seedling growth of V. faba was also recorded in vitro for the CFF, which displayed PGP traits of phosphate solubilization (48 mg/100 ml) as well as production of indole acetic acid (34 ㎍/ml) and ammonia (20 ㎍/ml). This study provided scientific validation that the new rhizobacterium Nocardiopsis alba strain BH35 could be further utilized in bioformulation and possesses biocontrol and plant growth-promoting capabilities.

• Microbiology and Biotechnology Letters
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• v.37 no.3
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• pp.280-286
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• 2009

To investigate anti-phytopathogenic fungal activity of Coptis chinensis, the methanol extract and its organic solvent fractions were prepared. Using the extract and the fractions, in-vitro spore-germination inhibition and mycelial-growth inhibition activities were evaluated against Colletotrichum gloeosporioides, Phytohpthora capsici, Pyricularia grisea, Rhizoctonia solani, Botryosphaeri dothidea, Glomerella cingulata, respectively. Treatment of the methanol extract (500 mg/mL) into the spore of phytopathogenic fungi completely inhibited germinations for 5 days, except B. dothidea, and showed strong antifungal activities against P. grisea and B. cinerea, and antioomycetes activity against P. capsici. The minimal growth inhibition concentrations of the methanol extract against P. grisea, B. cinerea and P. capsici were 300, 300, and 500 mg/mL, respectively. For practical application of C. chinensis in red-pepper field, the hot-water extract (1,000 mg/mL) was prepared in commercial facility, after evaluation of heat stability and solvent-extraction yields of antifungal substances. The 3-times leaf-spray of the extract from June to August, 2008 did not show any deleterious effect to red-pepper. In fact, the leaf-spray promoted plant growth including leaf, root and fruit. The average weight and rind of each fruit were increased to 119% and 117% comparison to those of without treatments. Our results suggest that C. chinensis is a useful source for control of red-pepper diseases and plant growth.

• Journal of the Korea Organic Resources Recycling Association
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• v.24 no.4
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• pp.85-94
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• 2016

The purpose of this study was to characterize the coffee ground and its possibility to develop the antifungal activity. pH, EC, and Zn contents of the coffee ground from coffee shops were higher than those of commercial coffee ground, but there was no significant difference in $K_2O$, CaO, MgO, $Na_2O$, Mn contents. The antimicrobial activity of the water soluble extracts from the coffee shop and the commercial coffee ground were tested for six major plant pathogens, Rhizoctonia solani, Sclerotinia sclerotiorum, Fusarium oxysporum, Phytophthora capsici, Alternaria alternata, and Botrytis cinerea. The result showed that there was reliable antifungal activity against all of tested plant pathogenic fungi. The inhibition effects of coffee ground compost extract on the spore germination and zoospore formation were investigated. Water soluble extracts of the coffee ground compost mixture added with 10% sesame oil cake were significantly inhibited the growth of conidia germination of A. altanata and zoospore formation of P. capsici in vitro. For investigating the functional materials of coffee ground compost, it was measured the total polyphenolic compounds contents with 30 days interval during decomposing coffee ground for 90 days. The total polyphenolic content increased with decomposing periods, and it observed that the highest total polyphenolic content was $0.35{\pm}0.03mg\;GAE/g$ on the 90th day in the coffee ground compost added with 10% sesame oil cake.

• Research in Plant Disease
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• v.14 no.3
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• pp.187-192
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• 2008

Five environment-friendly farm materials including $Chitomate^{(R)}$, $Diegyun^{(R)}$, IC-$66D^{(R)}$, Gold $Bordo^{(R)}$, and $Biospot^{(R)}$ were examined for their growth inhibition effect of the 7 fungal pathogens of grape in vitro. $Diegyun^{(R)}$, being composed of natural ingredients which are extracted from a plant, was the most effective in suppression of mycelial growth of the fungi. $Diegyun^{(R)}$ inhibited the mycelial growth of all of fungi over 75% at $2,500{\mu}g{\cdot}mL^{-1}$ on potato dextrose agar(PDA) except Colletotrichum gloeosporioides 04-159. Growth inhibition effect of $Chitomate^{(R)}$, being composed of the chitosan, varied depending on the fungal pathogens on PDA. It inhibited the mycelial growth of the Botrytis cinerea 06-063 at the rate of 75.8% at $40,000{\mu}g{\cdot}mL^{-1}$ on PDA while it inhibited the mycelial growth of the C. gloeosporioides 04-159 at the rate of 6.5%. IC-$66D^{(R)}$ and Gold $Bordo^{(R)}$ are two different formula of the Bordeaux mixture, showed different control effects on mycelial growth inhibition. Except of Acremonium sp. the growth inhibition of IC-$66D^{(R)}$ was a little higher than Gold $Bordo^{(R)}$. $Biospot^{(R)}$, a chlorine formula, showed the strongest growth inhibition on C. gloeosporioides 04-159 among the farm materials used. Inhibition of spore germination of $Chitomate^{(R)}$, $Biospot^{(R)}$ and Gold $Bordo^{(R)}$ was higher than mycelial growth inhibition for Pseudocercospora vitis 04-152. The results suggest that the different types of environment-friendly farm materials are needed for different disease control in organic grape farm.

• Journal of Life Science
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• v.18 no.7
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• pp.974-979
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• 2008

The powdery mildew, a fungal plant disease found in varieties of plant cultures, is occurred by attack with Fusarium sp., Sphaerotheca sp., Leveilluna sp., and Eryshipe sp.. In this study we investigated the control of Fusarium graminearum, a barley powdery mildew fungus, by natural plant extracts. Among the 900 plant extracts tested, Zanthoxylum schinifolium, Ligusticum acutilobum, Bidens frondosa L., Dictamnus dasycarpus, Evodia officinalis, Disporum sessile, Scopolia japonica Max., Styrax japonica S. et Z., Dictamnus dasycarpus Turcz., Sinomenium acutum Rehder et Wils., Eugenia aromaticum, Rubus parvifolius L., Reynoutria elliptica, Coptis chinensis, Paeonia lactiflora Pall., Rheum undalatum, Paeonia suffruticosa, Oenothera odorata Jacq., Euphorbia pekinensis Rupr., and Nepeta cataria were selected based on spore germination inhibition assay. Further mycelial growth inhibition assay with economical and safety considerations led us to finally select Z. schinifolium (sancho) for control of F. graminearum. To produce antifungal sancho extract, methanol was suitable for extraction and subsequent fractionations of the extract showed that the water residue mainly had antifungal activity. The sancho extract and its fractions showed minor antibacterial activity against different pathogenic or food spoilage bacteria, but they did not show any harmful effects against young tomato plant by treatment of $1,000\;{\mu}g/ml$ in green chamber test. These results suggested that the extract of sancho has high potentials on control of a powdery mildew fungus, F. graminearum.

• The Korean Journal of Pesticide Science
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• v.12 no.3
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• pp.291-294
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• 2008

The Streptomyces padanus isolate TH04, isolated from mummified peaches, showed strong antifungal activity to Monilinia fructicola. The inhibition activity of the isolate TH04 to mycelial growth and spore germination at 1% concentration of sub-antifungal powder made from culture suspension (CS) was ranged from 79.8% to 81.0% and from 73.9% to 75.8% to M. fructicola four strains, respectively. In the test of antifungal activity in mixed culture of the isolate and M. fructicola, inhibition rate was 7.5%, 86.8% and 94.0% in 0.01, 0.1, and 1% concentration of CS containing bacterial cell of the isolate, respectively. On apples (cultivar; Fuji), the control values of the isolate TH04 crude filtrates (0.1 and 1%) were 85.9% and 100%, respectively. The results suggest that the isolate TH04 indicate development possibility as biocontrol agent of brown rot caused by M. fructicola with the study on delivery method and fermentation condition to produce an antifungal compound.

• Microbiology and Biotechnology Letters
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• v.39 no.2
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• pp.168-174
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• 2011

In order to develop safe and economic novel antifungal agents, we prepared 73 methanol extracts from medicinal and edible herbs and examined their 365 solvent fractions using n-hexane, methylene chloride, ethylacetate, butanol and water residue based on the sequential organic solvent fraction method. When using the various fractions in the screening step for antifungal activity, we discovered ethylacetate fraction of Morus alba L., methylene chloride fraction of Pimpinella brachycarpa (MCPB), and n-hexane fraction of Salvia miltiorrhiza Bunge, which all have activities in methanol extracts, as potential sources of antifungal agents. Amongst these, the antifungal activity of P. brachycarpa has not to date been reported on. In addition, the mycelial growth inhibition and spore germination inhibition activities of MCPB against A. niger were confirmed by disc-diffusion assay in a 10 day culture. The MIC and MFC of MCPB were determined as 0.25 and 0.5 mg/ml, respectively. The MCPB has no hemolytic activity against human RBC at 0.5 mg/ml and glycoside-flavonoids are theorized to be active constituents. These results suggest that MCPB has a prominent antifungal activity and that the application of sequential organic solvent fractions, instead of simple natural product extracts, is useful in the screening process of novel bioactive substances.

• Research in Plant Disease
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• v.18 no.3
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• pp.201-209
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• 2012

The multi-function of 18 Bacillus subtilis isolates collected from agricultural extension centers of local government and National Academy of Agricultural Science was investigated by measuring their antifungal activities against five plant pathogens, such as Rhizoctonia solani, Colletotrichum acutatum, Fusarium oxysporum, Magnaporthe oryzae and Phytophthora capsici, phosphorus solubilization ability, production of indole acetic acid (IAA) and siderophore, and nitrogen fixation. The B. subtilis isolates showed antifungal activity against several plant pathogens and nitrogen fixation activity, and produced siderophore and IAA. They could control pepper powdery mildew (Leveillula taurica), but there was no difference in control efficacy among the B. subtilis isolates. In fields, the control efficacy of B. subtilis R2-1 ($10^8$ cells/ml) was compared with two microbial fungicides, Q-pect and Topsid. In 2009, the control efficacy of B. subtilis R2-1 (37.7%) was lower than that of Topsid (47.6%), but higher than that of Q-pect (25.7%). In 2010, the control efficacy of B. subtilis R2-1 (83.3%) was higher than that of Topsid (67.9%). In order to elucidate mode of action of B. subtilis R2-1 for controlling pepper powdery mildew, spore germination rates of pepper powdery mildew pathogen collected on treated leaves was investigated when suspensions of B. subtilis R2-1 and two microbial fungicides (Q-pect and Topsid) were foliar-sprayed. They highly suppressed spore germination of the pathogen with inhibition values of 84.2% for B. subtilis R2-1, 97.9% for Q-pect and 94.7% for Topsid. Further study on the mass-culturing method and formulation is needed for development of a microbial fungicide.