• Microbiology and Biotechnology Letters
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• v.20 no.3
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• pp.263-270
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• 1992

For the selection of powerful antagonistic bacterium for biological control of soil borne Eminia carotovora subsp. carotovora causing rot of vegetable, excellent strains (S4, S14, 565) were selected from 1,196 strains of bacteria which were isolated from rhizosphere in vegetable root rot-suppresive soil. Strains were identified to be Pseudomonas species with Api 20NE kit. Antagonistic substance was produced in 523 synthetic broth medium at pH 7~8 and $30^{\circ}C$ during 3 days culture. The substance was stable in the pH range of 6 to 9. When the basal medium was supplemented with mannitol and sorbitol as carbon source and calcium chloride as metal salt, the production of the inhibitory substance was increased. The inhibitory acitivity was increased by the addition of fertilizer in soil. The isolated strains were resistant to the agricultural chemical such as benomyl and fosethyl-Al-folpet, and the antibiotics such as penicillin and lincomycin. We had found that Pseudomonas sp. S14 strain had a single plasmid. After treated with acridin orange for curing, we confirmed the existence of antagonistic gene in the chromosomal DNA.

• Korean Journal of Agricultural Science
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• v.16 no.1
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• pp.36-43
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• 1989

Out of 826 isolates of Streptomyces isolated from different soils, their distribution and antibiotic productivity were investigated. Distribution of the organism in the soil was affected by the soil conditions and plants. The highest isolation frequency was occurred from Quercus forest, Robinia forest and grass field, while soils from orchards and cultivating fields showed low density of Streptomyces. More than 49% of the isolates showed antibacterial activity against Bacillus subtilis, Erwinia carotovora subsp. carotovora and Xantomonas campestris pv. oryzae and about 40% of the isolates showed antiyeasty activity against Saccharomyces cerevisiae but only a few isolates showed antibiotic activity against E. coli and Pseudomonas solanacearum. Forty isolates of the Streptomyces showed strong antifungal activity against Pyricularia oryzae. Rate of isolation of Streptomyces was the highest on starch agar among the eight media tested. Antibiotic productivity of the isolates was the highest on potato sucrose agar medium among the 5 media tested.

• The Korean Journal of Ecology
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• v.20 no.3
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• pp.181-189
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• 1997

Phenolic compounds from 7 species of naturalized invader species and Korean wild plants were analyzed by high performance liquid chromatography. Eleven phenolic compounds including benzoic acid were identified. The extract of naturalized plants was significantly more inhibitory to seed germination and seedling growth of the both naturalized and Korean wild plants. The content of total phenolic compounds in each extract were 43.5 mg/l in Ailanthus altissima as the maximum amount and 25.5 mg/l in Phytolacca americana as the minimum. Phytotoxic substances of ethanol extracts was investigated for antifungal activity against 23 selected fungus species. The antifungal activity of Phytolacca americana showed the greatest clear zone of 23 mm in Aspergillus awamori and its activity had an effect against 6 fungus species. Ailanthus altissima formed the greatest clear zone of 26 mm in Erwinia carotovora sub. sp. carotovora and had an effect agsinst 2 fungus species.

• The Korean Journal of Pesticide Science
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• v.10 no.1
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• pp.56-65
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• 2006

An antagonistic bacterial isolate, that inhibits the growth of plant pathogens, was selected and identified from 5,000 isolates screened from the rhizosphere of various crop plants. An isolate Bacillus sp. N32, tested against Colletotrichum gloeosporioides causing anthracnose disease in hot pepper, produced both a heat resistant antifungal protein and a heat sensitive antifungal protein. The heat resistant protein was partially purified by Ammonium sulfate fractionation and gel filtration chromatography. The bioautography showed that the proteins possessed high antifungal activity. The biosynthetic gene cluster responsible for the heat resistant antifungal protein was cloned from cosmid library using DNA probe obtained from PCR product with the primers targeting the conserved nucleotide sequence of the synthetic genes reported earlier, Most of the clones obtained showed higher homology to fengycin antibiotic synthetic gene family reported earlier. On the other hand, the heat sensitive protein was isolated from SDS-PAGE and electroblotting to determine the N-terminal amino acid sequences. The heat sensitive antifungal protein gene was cloned from the ${\lambda}-ZAP$ libraries using a DNA probe based on the N-terminal amino acid sequences of the heat sensitive protein. We are contemplating to clone and sequence the whole gene cluster encoding the heat sensitive protein for further analysis.

• Korean Journal of Agricultural Science
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• v.38 no.2
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• pp.205-212
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• 2011

The potential factors for quality loss of cleaned fresh ginseng and technology to be associated with the improvement of marketability through pre-packaging fumigation were examined. Major microorganisms isolated from fresh ginseng included Botrytis cinerea, and Erwinia sp. Others such as Cylindrocarpon sp., Fusarium spp., Pennicilium spp., Bacillus spp. were also found at relatively low frequency. The bacterial density of vacuum packaged fresh ginseng rapidly increased during simulated marketing. Little correlation between bacterial growth and package swelling was found. In order to improve packaging method of fresh ginseng, pre-packaging treatment of 2-phenylethyl alcohol (PE, 100 uL/L, 4 hr) was examined. The fumigation treatment effectively inhibited the growth of bacteria density and also effective on keeping firmness of ginseng root, especially in cortical portion. The internal gas compositions of plastic container packaged for ginseng were approximately ranged between 6 to 8% $O_2$and 3 to 4% $CO_2$. The $O_2$ level of fumigation treatment was lower than control whereas $CO_2$ level was higher. The upsurge of ethylene evolution I day after simulated marketing was found only in fumigation treatment but it returned to ordinary level at day 2. The sucrose content of 2-PE treatment was significantly reduced at 5 days after simulated marketing but reducing sugars like glucose and fructose remained at higher level. The difference in sugar levels was reduced after 10 days of simulated marketing. The decay of fresh ginseng began at the lateral or fine root, which is weak to physical damage, in general. The epidermis was more damaged. Plastic container packaging with PE fumigation could be an alternative to vacuum packaging, which allows an aerobic environment and prevents anaerobic respiration. Further study of pre-package fumigation is required to improve technology of fresh ginseng marketing.

• The Plant Pathology Journal
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• v.22 no.4
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• pp.375-380
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• 2006

In the survey from 1992 to 2000, twenty-eight parasitic diseases were observed in major apple producing areas in Korea. The predominant apple diseases were white rot(Botryosphaeria dothidea), Marssonina blotch(Marssonina mali), Valsa canker(Valsa ceratosperma), Alternaria leaf spot(Alternaria mali), and bitter rot(Collectotrichum gloeosporioides and C. acutatum). Apple scab that reappeared in 1990 after disappearance for 15 years was disappeared again since 1997. A viroid disease(caused by apple scar skin viroid) was newly found in this survey. The five diseases, fire blight(Erwinia amylovora), black rot(Botryosphaeria obtusa), scab(Cladosporium carpophilum), Monochaetia twig blight(Monochaetia sp.), and brown leaf spot(Hendersonia mali), which had once described in 1928 but no further reports on their occurrence, were not found in this survey. However, blossom blight(Monilinia mali), brown rot(Monilinia fructigena), and pink rot(Trichothecium roseum), which did not occur on apple after mid 1970s, were found in this survey.

• Natural Product Sciences
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• v.24 no.3
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• pp.159-163
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• 2018

Two new polyketides, chinoketides A and B (1 - 2) with a known compound xylarphthalide A (3), were isolated from the solid medium of the endophytes from the leaves of the relic plant Distylium chinense with the "black-box" co-culture method, and the structures of two new compounds were elucidated by NMR, MS and CD spectra. And the absolute configurations of chinoketides A (1) and B (2) were determined as 2R,3R,8S and 5R,6S by calculating their ECD spectra to compare with the experimental CD spectra. Finally, the antimicrobial activities were evaluated to Erwinia carotovora sub sp. Carotovora (Jones) Bersey et al, and the results showed that compounds 1 - 3 displayed the antimicrobial activities with MIC value at 20.5, 30.4 and $10.2{\mu}g/mL$.

• Journal of Microbiology and Biotechnology
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• v.19 no.1
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• pp.42-50
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• 2009

Fifty-four Pectobacterium carotovorum subsp. carotovorum strains isolated in Korea were characterized by a spectrum of antibacterial activities against 7 indicator strains chosen to represent various regions and host plants. All P. carotovorum subsp. carotovorum isolates tested could be grouped into 4 classes depending on the pattern of antibacterial substance production. All tested strains had DNA fragment(s) homologous to the genes encoding carotovoricin and 21 of them had genes homologous to DNA invertase. Sixteen strains had genes homologous to the genes encoding carocin S1. Several isolates produced antibacterial substances active against strains in Brenneria, Pantoea, and Pectobacterium genera that belonged formerly to the genus Erwinia. Strains in Pseudomonas or Xanthomonas sp. were not sensitive to the antibacterial substances produced by P. carotovorum subsp. carotovorum, except for X. albilineans that was sensitive to antibacterial substances produced by most strains in P. carotovorum subsp. carotovorum and P. betavasculorum KACC10056. These results demonstrated the diverse patterns of antibacterial substance production and the possibility of the existence of new antibacterial substance(s) produced by P. carotovorum subsp. carotovorum isolated in Korea.

• Journal of Mushroom
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• v.9 no.2
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• pp.69-73
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• 2011

We have researched on methods which can reduce fruit-body malformations of king oyster mushroom(Pleurotus eryngii). We collected many pathogens from diseased fruit-body or malformated fruit-body and identified with chemicobiological test and microscope. The factors of fruit-body malformations and increment of contamination during the pin-heading induction time were researched with ventilation amounts in growing room. When the pathogens having high pathogenicity were inoculated in spawn running bottle and at pin-heading induction time, symptom appeared or not appeared in according to air ventilation amounts in growing room. During the pin-heading induction time, humidity degree in growing room have kept of high level and air ventilation amounts were so little that fruit-body malformations ratio was high. But, even though pathogens were inoculated at the surface of bottle factitiously, if air ventilation amounts were enough, fruit-body malformation ratio was low.