• Mycobiology
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• v.40 no.1
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• pp.59-65
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• 2012

Antagonistic microorganisms against $Rhizoctonia$ $solani$ were isolated and their antifungal activities were investigated. Two hundred sixteen bacterial isolates were isolated from various soil samples and 19 isolates were found to antagonize the selected plant pathogenic fungi with varying degrees. Among them, isolate C9 was selected as an antagonistic microorganism with potential for use in further studies. Treatment with the selected isolate C9 resulted in significantly reduced incidence of stem-segment colonization by $R.$ $solani$ AG2-2(IV) in Zoysia grass and enhanced growth of grass. Through its biochemical, physiological, and 16S rDNA characteristics, the selected bacterium was identified as $Bacillus$ $subtilis$ subsp. $subtilis$. Mannitol (1%) and soytone (1%) were found to be the best carbon and nitrogen sources, respectively, for use in antibiotic production. An antibiotic compound, designated as DG4, was separated and purified from ethyl acetate extract of the culture broth of isolate C9. On the basis of spectral data, including proton nuclear magneric resonance ($^1H$ NMR), carbon nuclear magneric resonance ($^{13}C$ NMR), and mass analyses, its chemical structure was established as a stereoisomer of acetylbutanediol. Application of the ethyl acetate extract of isolate C9 to several plant pathogens resulted in dose-dependent inhibition. Treatment with the purified compound (an isomer of acetylbuanediol) resulted in significantly inhibited growth of tested pathogens. The cell free culture supernatant of isolate C9 showed a chitinase effect on chitin medium. Results from the present study demonstrated the significant potential of the purified compound from isolate C9 for use as a biocontrol agent as well as a plant growth promoter with the ability to trigger induced systemic resistance of plants.

• International Journal of Industrial Entomology and Biomaterials
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• v.31 no.2
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• pp.107-114
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• 2015

Endophytes provide multifarious benefits such as promotion of plant growth and yield, suppression of phyto-pathogens, phosphate solubilising and fixation nitrogen. A study has been carried out to explore growth promotion and antifungal activities of endophytes of mulberry (Morus spp.). Endophytic bacteria were isolated from mulberry plants and studied their cultural, morphological characters, growth promotion as well as their antifungal activity against Rhizoctonia bataticola and Fusarium oxysporum , two mulberry root rot associated pathogens. Except two isolates, all bacteria were colourless and the colony size of eight isolates was small. The margin of five isolates was irregular and the consistency of three isolates was creamy, six isolates was slimy and one was mucoid. Texture of seven isolates was convex and others were flat. Eight isolates were gram positive and the rest Gram negative, five were cocci and others were bacilli (rod shaped). Four isolates were motile and all were catalase positive and only three isolates were oxidase positive. Spore staining was positive only for two isolates. The growth promotion study showed that there was significant difference in root length and seedling length. The antagonistic effect of the bacterial isolates was tested against R. bataticola showed significant (p <0.05) influence of the bacteria, days after inoculation and their interaction on the inhibition of fungal growth. The isolate En-7 completely inhibited the fungus followed by En-5 (66.67%). The bacterial isolates significantly (p <0.05) inhibited growth of F. oxysporum in PDA. The mean inhibition was higher (70.45%) in case of En-7 followed by En-8 (68.65%) and En-10 (66.44%). The study reveals that some endophytic bacteria associated with mulberry have growth promotion and antifungal activity and could be explored for promotion of mulberry growth and managing root rot disease.

• Journal of Microbiology and Biotechnology
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• v.13 no.1
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• pp.77-84
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• 2003

Chitinase was purified from an antagonistic bacterium Bacillus sp. 7079 by ammonium sulfate precipitation, QAE-Sephadex anion exchange chromatography, Sephadex G-100 gel filtration, and SP-Sephadex cation exchange chromatography. The molecula. weight of purified chitinase (PC-1) was approximately 66.5 kDa on SDS-PACE. PC-1 exhibited optimum pH and temperature of pH 7.5 and $45^{\circ}C$, respectively. More than $80\%$ of PC-1 was stable at pH 5.0 to 9.0, and more than $90\%$ at $40^{\circ}C$. $Fe^2+\;and\;Ca^2+$ inhibited the chitinase activity about $20\%$, and EDTA and p-CMB by about $30\%$, whereas $Ag^+$ inhibited the activity up to $65\%$. The $K_m$ value of PC-1 was 1.215 mg/ml with colloidal chitin as a substrate. We also investigated the effect of PC-1 treated chitin (PCTC) on the pro-inflammatory cytokine gene expression in macrophage RAW 264.7 cells. The expression of IL-$1{\alpha}$ and IL-$1{\beta}$ mRNA gene was investigated using reverse transcriptase polymerase chain reaction (RT-PCR). IL-$1{\alpha}$ and IL-$1{\beta}$ mRNA were induced by the treatment of PCTC and chitin only in RAW 264.7 cells. These expressions were induced as early as 2 h and sustained up to 24 h in RAW 264.7 cells. IL-$1{\alpha}$ and IL-$1{\beta}$ mRNA were more strongly expressed by the treatment of PCTC than chitin treatment alone in RAW 264.7 cells.

• Journal of Ginseng Research
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• v.21 no.2
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• pp.109-114
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• 1997

The effect of total saponin fraction of Ginseng injected intrathecally (i.1.) or in- tracerebroventricularly (i.c.v.) on the antinociception induced by D-$Pen^{2,5}$- enkephalin (DPDPE) ad ministered i.c.v. was studied in ICR mice in the present study. The antinociception was assessed by the tail-flick test. Total saponin fraction at doses 0.1 to 1.0 $\mu\textrm{g}$, which administered i.t. Alone did not affect the latencies of tail-flick threshold, attenuated dose-dependently the inhibition of the tail-flick response induced by i.c.v. administered DPDPE (10 $\mu\textrm{g}$). However, total saponin fraction at doses 1 to 20 $\mu\textrm{g}$, which administered i.c.v. Alone did not affect the latencies of the tail-flick response, did not affect i.c.v. administered DPDPE (10 $\mu\textrm{g}$)-induced antinociception. The duration of antagonistic action of total saponin fraction against DPDPE-induced antlnociception was lasted at least for 6 hrs. Various doses of ginsenosides Rd, but not $\Rb_2$, Rc, Rg1, and $\Rb_1$ and Re, injected i.t. Dose-dependently attenuated antinociception induced by DPDPE administered i.c.v. Our results indicate that total saponin fraction injected spinally appears to have antagonistic action against the antinociception induced by supraspinally applied DPDPE. Ginsenoside Rd appears to be responsible for blocking j.c.v. administered DPDPE-induced antinociception. On the other hand, total ginseng fraction, at supraspinal sites, may not have an antagonistic action against the antinociception induced by DPDPE.

• The Plant Pathology Journal
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• v.29 no.2
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• pp.154-167
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• 2013

We previously developed a sequential screening procedure to select antagonistic bacterial strains against Phytophthora capsici in pepper plants. In this study, we used a modified screening procedure to select effective biocontrol strains against P. capsici; we evaluated the effect of selected strains on Phytophthora blight and anthracnose occurrence and fruit yield in pepper plants under field and plastic house conditions from 2007 to 2009. We selected four potential biocontrol strains (Pseudomonas otitidis YJR27, P. putida YJR92, Tsukamurella tyrosinosolvens YJR102, and Novosphingobium capsulatum YJR107) among 239 bacterial strains. In the 3-year field tests, all the selected strains significantly (P < 0.05) reduced Phytophthora blight without influencing rhizosphere microbial populations; they showed similar or better levels of disease suppressions than in metalaxyl treatment in the 2007 and 2009 tests, but not in the 2008 test. In the 2-year plastic house tests, all the selected strains significantly (P < 0.05) reduced anthracnose incidence in at least one of the test years, but their biocontrol activities were variable. In addition, strains YJR27, YJR92, and YJR102, in certain harvests, increased pepper fruit numbers in field tests and red fruit weights in plastic house tests. Taken together, these results indicate that the screening procedure is rapid and reliable for the selection of potential biocontrol strains against P. capsici in pepper plants. In addition, these selected strains exhibited biocontrol activities against anthracnose, and some of the strains showed plant growth-promotion activities on pepper fruit.

• Research in Plant Disease
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• v.28 no.3
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• pp.152-161
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• 2022

Several types of chemical bactericides have been used to control fire blight. However, their excessive usage leads to environmental deterioration. Therefore, several researchers have analyzed antagonistic microorganisms as promising, effective, and safe biological control agents (BCAs). The primary aim of this study was to screen for potential antagonistic bacteria that suppress Erwinia amylovora. Among the 45 isolates studied, 5 strains showed the largest inhibition zone against E. amylovora. 16S rRNA gene sequencing identified them as Bacillus amyloliquefaciens (KPB 15), B. stratosphericus (KPB 21), B. altitudinis (KPB 25), B. safensis (KPB 31), and B. subtilis (KPB 39). KPB 25 and 31 reduced the lesion size of fire blight by 50% in immature apple fruits, and did not show antagonism against each other. Therefore, KPB 25 and 31 were selected to develop an antagonistic mixture against fire blight. Although the mixture with KPB 25 and 31 showed a slightly increased ability to reduce lesion size on immature fruits, they did not exhibit a synergistic effect in reducing E. amylovora population compared to each strain alone. Nevertheless, we have identified these two strains as useful and novel BCAs against fire blight with additional benefits safety and potential in developing a mixture without loss of their activity, owing to the absence of antagonism against each other.

• Animal cells and systems
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• v.1 no.4
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• pp.641-646
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• 1997

Lysophosphatidic acid (LPA; 1-acyl-glycerol-3-phosphate) has been known as an intercellular phospholipid messenger with a wide range of biological activities. In this study, the effect of LPA on both the proliferation and differentiation of rat E63 myoblasts has been investigated. In the serum-free Insulin-Transferrin-Selenium (ITS) media, the proliferation of E63 cells was largely restricted. Addition of LPA into the ITS media strongly promoted the cell proliferation and resulted in two to four fold increase of cell number. Furthermore, it appeared to increase the percent fusion in a dose-dependent manner up to 15 ug/ml. The synthesis of myosin heavy chain (MHC) was increased by LPA as well. These results indicate that LPA is able to promote both cell proliferation and differentiation in rat E63 myoblasts. Suramin, known to have uncoupling activity on growth factor-receptor interaction, was tested for antagonistic activity in myoblast proliferation and differentiation. Myoblasts grown in the ITS medium containing LPA were able to proliferate well even in the presence high concentration of suramin whereas myoblast differentiation was completely blocked by 30 ug/ml of suramin. The inhibitory effect of suramin on the myoblast differentiation was completely reversible by removing the suramin. This result indicates that the intracellular signaling pathway of LPA leading to cell proliferation might be distinct from that leading to cell differentiation on E63 myoblasts. Also, the antagonistic effect of suramin suggests that the differentiation activity elicited by LPA might be mediated by a specific G protein-coupled receptor.

• Asian Journal of Turfgrass Science
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• v.11 no.3
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• pp.173-183
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• 1997

This study was conducted to develop an integrated disease management system against large patch disease. Attempts were made to estimate the effect of calcium hydroxide, silicate fertilizer and urea on the mycelial growth of Rhizoctonia sotani AG2-2 and the development of large patch in vitro and in vivo and to establish the most promising combination of fertilizer, fungicide and antagonistic microbes. 1.The mycelial growth of Rhizoctonia sotani AG2-2 were completely inhibited at 2,000, 1,000 and 3,000ppm concentration by calcium hydroxide, silicate fertilizer and urea, respectively. Inhibition effect of silicate fertilizer was the highest, but that of urea was the lowest compared with other treatments. 2.Treatment of calcium hydroxide at rate of l00g /$m^2$ was the most effective, and control effect appeared from 30 days after treatment in spring, which was better in autumn than in spring. Silicate fertilizer treated at rate of l00g /$m^2$, 200g /m$^2$, in spring and 50g /$m^2$ in autumn were very effective. Urea at rate of 30g /$m^2$ was more effective than 60g /m$^2$ and 120g /m$^2$. 3.The efficacies of mepronil and toclofos-methyl, applied twice in spring and once in autumn, were 83.8% in spring, which persisted to 70% in autumn compared with untreated plot. 4.The efficacies of Trichoderma harzianum were the highest by 55% in spring, but those of Bacillus amyloliquefaciens BL-3 and Peudomonas putida were the highest by 80% in autumn among other antagonists tested, when two organisms were applied twice in spring and once in autumn.

• Research in Plant Disease
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• v.16 no.1
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• pp.35-40
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• 2010

Suppression effect of the 12 bacterial isolates from plant rhizosphere against late blight caused by Phytophthora citrophthora were investigated on citrus fruits. Among the bacterial isolates, THJ609-3, TRH423-3, BRH433-2, Lyso-chit and KRY505-3 presented disease suppression after wound inoculation with the fungal pathogen in vivo. The anti-fungal activity was evaluated by measuring the length of inhibition zone of the mycelium P. citrophthora adjacent to the effective bacterial isolates in which all of the 5 bacterial isolates showed antagonistic effects. However, there was no positive correlations between the efficacy of disease suppression and the antagonistic effect. On the other hand, Lyso-chit and KRY505-3 were identified as Bacillus cereus, BRH433-2 as B. circulans and TRH423-3 as Burkholderia gladioli, respectively, by analysis of rDNA sequence on the internal transcript spaces. It is suggested that the effective bacterial isolates may be useful for finding biological control agents against late blight especially on environment-friendly farm where the application of fungicide is limited.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.7
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• pp.1057-1065
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• 2002

The antagonistic activities of 30 strains of lactobacilli against Helicobacter pylori were determined and Lactobacillus helveticus CU631 has been selected as the strain which possesses the strongest inhibitory effect in the disc diffusion assay showing inhibition zone diameter of $10{\pm}1.5mm$, whereas those of L. plantarum and L. fermentum have been shown to be $4.0{\pm}0.6mm$. H. pylori G88016 revealed the highest vacuolating toxin producing activity among the 8 strains, the inhibitory activity of L. helveticus CU631 in vacuolating toxin producing activity of H. pylori manifested in the co-culture of two strains and in the 5:5 mixture of supernatant of the two strains. Both L. helveticus CU631 and cell free culture supernatant had a strong inhibitory activities in urease and cytotoxin producing activities of H. pylori NCTC11637 and CJH12. An accelerated proteolytic activity of water soluble peptides by L. helveticus CU631 during the refrigeration storage has been manifested in the cream cheese. DNA seqences of 16S-23S ribosomal RNA spacer region showed typical pattern among the various strains of L. helveticus, which could be used in the identification of L. helveticus CU 631.