• Korean Journal of Environmental Agriculture
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• v.40 no.1
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• pp.20-32
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• 2021

BACKGROUND: Bacterial shot hole of stone fruits is a seriuos plant disease caused by Xanthomonas arboricola pv. pruni (Xap). Techniques to control the disease are required. In this study, microorganisms with antibacterial activity were isolated to develop as a microbial agent against the bacterial shot hole. METHODS AND RESULTS: An isolate with the strongest activity among the isolates was identified as Streptomyces avidinii based on 16S rRNA gene sequence analysis and designated Streptomyces sp. J46. J46 showed suppression of bacterial leaf spot with a control value of 90% at 10 times-diluted cell free supernatant. To investigate antibacterial metabolites produced by J46, the supernatant of J46 was extracted with organic solvents, and the extracts were subjected to chromatography works. Antibacterial metabolites were not extractable with organic solvents. Both reverse and normal phase techniques were not successful because the metabolites were extremely water soluble. The antibacterial metabolites were not volatiles but protein compounds based on hydrolysis enzyme treatment. CONCLUSION: Our study suggests that Streptomyces sp. J46 may be a potential as an microbial agent against bacterial shot hole. Further study to identify the metabolites is required in more detail.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.135-136
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• 2000

A bacterial strain producing a large amount of EPS was isolated from marine sediment sample collected from the Cheju Island, Republic of Korea. In the present study, the isolation and identification of this isolate, which is named Hahella chejuensis gen. nov., sp. nov., the effects of nutrients on the production of EPS, and some properties of this EPS are reported.

• Proceedings of the Turfgrass Society of Korea Conference
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• 2011.02a
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• pp.35-35
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• 2011

A large patch disease caused by Rhizoctonia solani AG2-2(IV) is a serious problem in turfgrass sites including golf courses and sports fields in Korea. The objectives of this study were to isolate some antagonistic microorganisms and to explain some involving mechanisms. Initially single colonies which were formed from the filtrates of various soil samples were obtained from LB culture and then co-cultured with R.solani AG2-2(IV) on PDA plate to explore some antagonistic microbes against for large patch fungus, Rhizoctonia solani AG2-2(IV). Out of total 82 antagonistic isolates which commonly had inhibition effect on Rhizoctonia solani AG2-2(IV) mycelial growth, one candidate (YPIN22) showed the most antifungal effect, which was confirmed by the longest distance from the edge of bacterial colony to the mycelial edge of the Rhizoctonia solani AG2-2(IV) in the dual culture. A succeeding investigation was to test any potential effect of the isolate on growth inhibition of 5 other turfgrass pathogens including R. solani solani AG2-2(IIIB), P. ultimum, C. caudatum, C. lunata, and F.oxysporum. Preliminary result indicated that the new isolate YPIN22 was also found to have antagonistic potential on the growth inhibition of those turfgrass pathogenic fungi, which was explained by inhibition zones ranging from 8 to 22mm. A further explanation of some characteristics of the isolate YPIN22 will be discussed in detail.

• Journal of Microbiology
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• v.37 no.4
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• pp.206-212
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• 1999

In order to isolate a Fe(III)-reducer from the natural environment, soil samples were collected from various patty fields and enriched with ferric citrate as a source of Fe(III) under anaerobic condition. Since the enrichment culture was serially performed, the Fe(III)-reduction activity was serially diluted and cultivated on an agar plate containing lactate and ferric citrate in an anaerobic glove box. A Gram negative, motile, rod-shaped and facultative anaerobic Fe(III)-reducer was isolated based on its highest Fe(III)-reduction activity, Bacterial growth was coupled with oxidation of lactate to Fe(III)-reduction, but the isolate fermented pyruvate without Fe(III), The isolate reduced an insoluble ferric iron (FeOOH) as well as a soluble ferric iron (ferric citrate). Using the BBL crystal enteric/non-fermentor identification kit and 16S rDNA sequence analysis, the isolate was identified as Shewanella putrefaciens IR-1.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.3
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• pp.151-155
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• 2005

This study was carried out to get information for diversifying of resistant genes to bacterial blight (BB) in Japonica cultivar breeding programs. TWo hundred nine rice varieties were tested for qualitive resistance to four races of BB; HB9101 isolate for race K1, HB9102 isolate for race K2, HB9103 isolate for race K3, and HB01001 isolate for race K3a. Two hundred nine rice varieties were divided into five groups according to their race reaction. Fourteen Tongil-type varieties and ninetyseven Japonica varieties showed susceptible reaction to four races; Kl, K2, K3 and K3a. Thirteen Tongil-type varieties and thirty-one Japonica varieties were resistant to only one race; K1. Nine Tongil-type varieties and one Japonica variety were resistant to two races; K1 and K2. One Tongil-type variety and twenty-eight Japonica varieties were resistant to the three races; K1, K2, and K3. Fourteen Tongil-type varieties and one Japonica variety were resistant to four races; K1, K2, K3, and K3a. A number of Tongil-type varieties showed broad spectrum resistance to four races, while a number of Japonica varieties showed broad spectrum resistance to three races; K1, K2, and K3.

• Mycobiology
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• v.46 no.2
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• pp.147-153
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• 2018

Certain beneficial microorganisms isolated from rhizosphere soil promote plant growth and induce resistance to a wide variety of plant pathogens. We obtained 49 fungal isolates from the rhizosphere soil of paprika plants, and selected 18 of these isolates that did not inhibit tomato seed germination for further investigation. Based on a seed germination assay, we selected four isolates for further plant tests. Treatment of seeds with isolate JF27 promoted plant growth in pot tests, and suppressed bacterial speck disease caused by Pseudomonas syringae pathovar (pv.) tomato DC3000. Furthermore, expression of the pathogenesis-related 1 (PR1) gene was higher in the leaves of tomato plants grown from seeds treated with JF27; expression remained at a consistently higher level than in the control plants for 12 h after pathogen infection. The phylogenetic analysis of a partial internal transcribed spacer sequence and the b-tubulin gene identified isolate JF27 as Aspergillus terreus. Taken together, these results suggest that A. terreus JF27 has potential as a growth promoter and could be used to control bacterial speck disease by inducing resistance in tomato plants.

• Journal of the Korean Society of Tobacco Science
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• v.26 no.2 s.52
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• pp.79-84
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• 2004

During the screening of antiviral substances having inhibitory effects on tobacco mosaic virus (TMV) infection to tobacco plants, we found a bacterial isolate KTGBP10, which was identified as a Stenotrophomonas sp., strongly inhibited the infection of TMV. When the culture filtrate from KTGBP10 was applied on the upper surface of leaves of Xanthi-nc tobacco plants at the same time or 24 hours before TMV inoculation, almost complete inhibition of TMV infection was achieved. And $40\%$ inhibition was shown with application of the culture filtrate to the under surface of leaves. In field trials, transmission of TMV from diseased seedlings to the healthy ones during transplanting work was reduced by $87.1\~92.6\%$ when the culture filtrate or cell suspension was sprayed onto the tobacco seedlings, cv. NC82, 24 hours before transplanting. No toxic effect was observed on the tobacco plants. When the broth filtrate of KTGBP10 was supplied by soaking through the cut-leaves before and/or after virus inoculation, the TMV infection was also inhibited by $50.4\~65.3\%$.

• Food Science of Animal Resources
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• v.31 no.3
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• pp.405-412
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• 2011

The purpose of this study was to isolate and characterize bacteriocin-producing bacteria against Clostridium perfringens from domestic animals to determine their usefulness as probiotics. The feces of cattle and chicken were used as sources to isolate bacteriocin-producing bacteria using the spot-on-lawn method. In total, 900 bacterial stains were isolated from domestic animal feces, and 19 strains were finally selected after determining the inhibitory activity against the pathogenic indicator C. perfringens KCTC 3269. Eighteen strains of Bacillus subtilis and one strain of Brevibacillus parabrevis were identified by 16s rRNA sequencing. Most of the bacterial strains isolated were resistant to 0.5% bile salts and remained viable after 2 h at pH 3.0. Additionally, some B. subtilis strains showed strong inhibitory activity against Listeria monocytogenes. We isolated and screened B. subtilis strains CB 153 and CB 189 from cattle and B. subtilis MSC 156 and B. parabrevis MSC 164 from chickens using probiotic selection criteria such as inhibition activity against C. perfringens and tolerance to acid and bile salts. The isolated bacteriocin-producing bacteria and/or bacteriocin have the potential to be used as probiotics in the livestock industry.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.6
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• pp.852-860
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• 2012

An Antarctic bacterial isolate displaying extracellular ${\alpha}$-galactosidic activity was named Paenibacillus sp. LX-20 based on 16S rRNA gene sequence analysis. Optimal activity for the LX-20 ${\alpha}$-galactosidase occurred at pH 6.0-6.5 and $45^{\circ}C$. The enzyme immobilized on the smart polymer Eudragit L-100 retained 70% of its original activity after incubation for 30 min at $50^{\circ}C$, while the free enzyme retained 58% of activity. The enzyme had relatively high specificity for ${\alpha}$-D-galactosides such as p-nitrophenyl-${\alpha}$-galactopyranoside, melibiose, raffinose and stachyose, and was resistant to some proteases such as trypsin, pancreatin and pronase. Enzyme activity was almost completely inhibited by $Ag^+$, $Hg^{2+}$, $Cu^{2+}$, and sodium dodecyl sulfate, but activity was not affected by ${\beta}$-mercaptoethanol or EDTA. LX-20 ${\alpha}$-galactosidase may be potentially useful as an additive for soybean processing in the feed industry.

• Journal of Microbiology and Biotechnology
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• v.23 no.7
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• pp.897-904
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• 2013

Seven bacterial isolates (viz., AB05, AB10, AB11, AB12, AB14, AB15, and AB17) were derived from the rhizosphere and evaluated in terms of plant growth-promoting activities and the inhibition of Phytophthora infestans affecting tomatoes in Korea. According to 16S rDNA sequencing, a majority of the isolates are members of Bacillus, and a single isolate belongs to Paenibacillus. All seven isolates inhibited P. infestans by more than 60% in vitro. However, AB15 was the most effective, inhibiting mycelial growth of the pathogen by more than 80% in vitro and suppressing disease by 74% compared with control plants under greenhouse conditions. In a PGPR assay, all of the bacterial isolates were capable of enhancing different growth parameters (shoot/root length, fresh biomass, dry matter, and chlorophyll content) in comparison with non-inoculated control plants. AB17-treated plants in particular showed the highest enhancement in fresh biomass with 18% and 26% increments in the root and shoot biomass, respectively. However, isolate AB10 showed the highest shoot and root growth with 18% and 26% increments, respectively. Moreover, the total chlorophyll content was 14%~19% higher in treated plants.