• Proceedings of the Korean Society of Life Science Conference
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• 2007.10a
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• pp.74.1-74.1
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• 2007

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• Proceedings of the Korea Environmental Mutagen Society Conference
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• 2004.05a
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• pp.93-93
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• 2004

• Korean Journal of Microbiology
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• v.52 no.4
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• pp.437-443
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• 2016

In this study Streptomyces strains were isolated from soils and their antifungal activities and involved mechanisms were investigated. Among over 400 isolates of actinomycetes, Streptomyces costaricanus HR391 was selected as a potential antagonist to control several plant-pathogenic fungi. S. costaricanus HR391 inhibited mycelial growth of Fusarium oxysporum f. sp. raphani, F. oxysporum f. sp. niveum, F. oxysporum f. sp. lycopersici, and Rhizoctonia solani by 26.5, 26.2, 21.2, and 23.8%, respectively compared to those of uninoculated control after 7-day incubation on PDB medium. S. costaricanus HR391 produced $89{\mu}M$ of siderphore, and showed fungal cell wall-degrading activity including $0.46{\mu}mol/min/mg$ of chitinase and $0.83{\mu}mol/min/mg$ of ${\beta}$-1,3 glucanase. S. costaricanus HR391 secreted 87.49 mg/L of rhamnolipid, and produced 9.49 mg/L and 4.3 mM of lipopeptide, iturin A and surfactin, respectively, all they are membrane-disrupting biosurfactants. It also produced antimicrobial peptide and antibiotics phenazine. In addition to antifungal substances, S. costaricanus HR391 secreted plant growth-promoting phytohormones, zeatin, gibberellins and IAA. These results suggest that S. costaricanus HR391 may be utilized as an environment-friendly biocontrol agent against some important pathogenic fungi.

• The Korean Journal of Mycology
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• v.24 no.4 s.79
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• pp.310-321
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• 1996

Five strains AF027, AF069, AF2001, AF2011 and SD02 of Pseudomonas cepacia were isolated from soil, and the antifungal cyclic lipopeptides(CLP) i.e, CLP027A, CLP069A, Cepacidine A, CLP2011A and CLP02A were produced from each strains, respectively. Nitrogen and carbon sources in media were proved to be important factors for the production of CLP and among them, polypeptone-S, glucose and fructose were the most effective. It appeared that compounds CLP027A and CLP069A were identical with Cepacidine A and Xylocandine A, respectively. contain aspartic acid as amino acid component, are differentiated from Xylocandine A containing asparagine. Although molecular weight, amino acid composition and UV spectrum of CLP2011A and CLP02A are same with those of Cepacidine A, it is postulated that these compounds are not identical with Cepacidine A when the antifungal spectra and antifungal activity were compared to those of Cepacidine A.

• Korean Journal of Microbiology
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• v.54 no.3
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• pp.272-279
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• 2018

This study was carried out to evaluate antimicrobial activity of isolated bacteria from various soils against two strains of Propionibacterium acnes causing acne vulgaris. Among several hundreds of bacterial strains, Paenibacillus elgii DS381, Paenibacillus elgii DS1515, Burkholderia gladioli DS518, and Streptomyces lienomycini DS620 showed high antimicrobial activities against the strains of P. acnes. All isolated bacteria showed 15.5 to 34.3 mm inhibition zone diameter in an agar well diffusion test, and especially DS620 showed the highest inhibition zone diameters (28.3~34.3 mm). Antibacterial substances were expected as lipopeptide (pelgipeptin and paenipeptin) from strains DS381 and DS1515, protease from DS518, and anthracycline antibiotic (daunomycinone) from DS620, and all these showed very low minimum inhibitory concentration [DS381 and DS1515 (0.078 mg/ml), DS518 (0.312 mg/ml), DS620 (0.000078 mg/ml)] against P. acnes. These antibacterial substances could completely kill P. acnes within 24 h in a time-kill assay. These results suggest that antibacterial substances produced by these bacteria may be utilized as useful antimicrobial agent against P. acnes and treatment medicine for acne vulgaris.

• Journal of Microbiology and Biotechnology
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• v.21 no.5
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• pp.536-539
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• 2011

Nowadays, there are a number of colorimetric techniques available for the determination of a time killing assay in a manner much easier and faster than those previously more commonly used, which were much more time-consuming and laborious colony counting procedures. Here, an attempt has been made to test the antimicrobial peptides of Citropin 1.1, Palm-KK-$NH_2$, and Temporin A on a reference strain of Staphylococcus aureus using resazurin as the cell viability reagent. Staphylococcus aureus was exposed to the test compounds over varying periods of time and the metabolic activity measured, with a profile of antimicrobial activity then established. The results are in agreement with data from previous literature, thus confirming the relevance of the application of resazurin for the testing of antimicrobial agents.

• The Plant Pathology Journal
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• v.32 no.3
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• pp.273-280
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• 2016

Most biocontrol agents for plant diseases have been isolated from sources such as soils and plants. As an alternative source, we examined the feces of tertiary larvae of the herbivorous rhino beetle, Allomyrina dichotoma for presence of biocontrol-active microbes. The initial screen was performed to detect antifungal activity against two common fungal plant pathogens. The strain with strongest antifungal activity was identified as Bacillus amyloliquefaciens KB3. The inhibitory activity of this strain correlated with lipopeptide productions, including iturin A and surfactin. Production of these surfactants in the KB3 isolate varied with the culture phase and growth medium used. In planta biocontrol activities of cell-free culture filtrates of KB3 were similar to those of the commercial biocontrol agent, B. subtilis QST-713. These results support the presence of microbes with the potential to inhibit fungal growth, such as plant pathogens, in diverse ecological niches.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2010.05a
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• pp.6-6
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• 2010

Bacteria of the Bacillus sp. are well known to possess antagonistic activity against numerous plant pathogens. In the present study, 11 Bacillus sp. were isolated from the brackish environment and assayed for antagonistic activity under in vitro and in vivo conditions. Among the 11 isolates tested, 9 isolates effectively inhibited the growth of various plant pathogens, namely Phytophthora capsici, Phytophthora citropthora, Phytophthora citricola, Phytophthora sojae, Colletotricum coccodes, Colletotricum gloeosporioides, Colletotricum acutatum, Rhizoctonia solani, Fusarium solani, Fusarium graminearum, Pyricularia sp. and Monilina sp. The effective isolates were further screened for Phytophthora blight suppression in Capsicum annuum L. under green house conditions. The isolate SB10 exhibited the maximum (72.2%) reduction in disease severity. The antifungal compounds from the isolate were isolated and characterized. The isolated compounds exhibited high thermo stability ($100^{\circ}C$ for 30 min). Matrix-Assisted Laser Desorption Ionization-Time of Flight investigation of the antifungal compounds revealed three lipopeptide complexes, the surfactins, the iturins, and the fengycins.

• Journal of Mushroom
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• v.9 no.4
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• pp.180-185
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• 2011

Spent mushroom substrates (SMS) is a by-product remaining after a crop of mushrooms. About four surfactin-producing strains were isolated from SMS (Pleurotus eryngii). Among of them, one isolate, which designated to YJ07, potentially showed the antifungal activity against Aspergillus flavus and Aspergillus ochraceous producing mycotoxin on PDA medium. The biochemical characteristics of the strain YJ07 was similar with Bacillus subtilis and Bacillus amyloliquefaciens by Bacillus ID kit and VITEK 2 system. Comparative 16S rDNA gene sequence analysis of the strain YJ07 also showed that the strain YJ07 was most closely related to Bacillus amyloliquefaciens with sequence similarity of 99.5%. On the basis of their biochemical characteristics and phylogenetic distinctiveness, the strain YJ07 was classified within the genus Bacillus as Bacillus amyloliquefaciens YJ07. The antifungal compound from B. amyloliquefaciens YJ07 was similar to lipopeptide surfactin from Bacillus subtilis by TLC and HPLC analysis.

• Journal of Life Science
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• v.21 no.10
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• pp.1481-1486
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• 2011

Spent mushroom substrate (SMS) is a by-product remained after a crop of mushrooms. About seven thermophilic strains were isolated from SMS (Flammulina velvtipes). Among them, one isolate, designated UJ03, showed the antifungal activity against Aspergillus flavus and Aspergillus ochraceous producing mycotoxin on PDA medium, potentially. The strain UJ03 produced cellulase and xylanase as extracellular hydrolases. The strain UJ03 was identified as a member of the genus Bacillus by biochemical characteristics using Bacillus ID kit and VITEK 2 system. Comparative 16S rDNA gene sequence analysis showed that strain UJ03 formed a distinct phylogenetic tree within the genus Bacillus and was most closely related to Bacillus amyloliquefaciens with sequence similarity of 98.9%. On the basis of its physiological properties, biochemical characteristics and phylogenetic distinctiveness, strain UJ03 was classified within the genus Bacillus, for which the name Bacillus sp. UJ03 is proposed. The antifungal compound from Bacillus sp. UJ03 was similar to lipopeptide iturin A of Bacillus sp.