• Korean Journal of Microbiology
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• v.43 no.4
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• pp.279-284
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• 2007

Two bacterial strains isolated from soil (Bacillus subtilis strains: PS2 and RFO41) were evaluated to determine their promoting effect on the growth of tomato seedling under axonic and pot conditions. The production of phytohormone, such as indole-3-acetic acid, indole-3-butyric acid, gibberellin and zeatin by these two strains was investigated as possible mechanisms for plant growth stimulation. Both PS2 and RFO41 were shown to produce various phytohormones, and. the production of phytohormones was stimulated by the addition of peptone-rich brain heart broth medium. In addition, these bacteria exhibited high levels of phosphatase activity, which ranged from 2.18 to $2.7\;{\mu}\;{\rho}-nitrophenol/ml/hr$. PS2 and RFO41 were applied to the pot test for growth of tomato seed with phosphate. Root and shoot lengths of germinated tomato after 15 days were 45.5% and 36.5% longer than that of control in RFO41 treated samples, respectively. Baciller sp. PS2 and RFO41 may have a potential for biofertilizer in the agriculture.

• The Plant Pathology Journal
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• v.20 no.1
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• pp.52-57
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• 2004

Sclerotinia sp. (isolate BWC98-105) causes stem blight and root rot in Leghum sp., and is presently being evaluated as a potential mycoherbicide for the control of Trifoliorium repens. Bioassays have shown that Sclerotinia sp. produces phytotoxic substance which is biologically active against T. repens. Two biologically active compounds, designated as compoundsI and II, were produced in vitro from the culture filtrate of BWC98-105 isolate Sclerotium sp. Compounds I and II were purified by means of liquid-liquid extraction and $C_{18}$ open column chromatography (300 ${\times}$ 30 mm, i.d). To determine the purity, the purified compounds were analyzed by RP-HPLC. The analytical RP-HPLC column was a TOSOH ODS-120T (150 ${\times}$ 4.6 mm i.d, Japan), of which the flow rate was set at 0.7 mL/min using the linear gradient solvent system initiated with 15 % methanol to 85 % methanol for 50 min with monitoring at 254 nm. Under these RP-HPLC conditions, compounds I and II eluted at 3.49 and 4.13 min, respectively. Compound II was found to be most potent and host specific. However, compound I had a unique antibiotic activity against phytopathogenic bacteria like bacterial leaf blight (Xanthomonas oryzae) on rice, where it played a less important role in producing toxicity on T. repens. No toxin activity was detected in the water fraction after partitioning with several organic solvents. However, toxin activity was detected in the ethyl acetate and butanol fractions. In the leaf bioassay using compound II, the disease first appeared within 4-5 h as water soaked rot, which subsequently developed into well-defined blight affecting the whole plant.

• Research in Plant Disease
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• v.13 no.2
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• pp.93-97
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• 2007

The microorganisms with the antifungal activity against Phytophthora capsici and Colletotrichum acutatum and the plant growth promotion activity were screened from forest soils of Moon-gyeong (Juheul Mountain), Gyeongsangbuk-do. One of the isolates, strain MG 121 showed antifungal activity against P. capsici and C. acutatum and possessed phosphate solubilization activity was selected to development biocontrol agent. The strain MG 121 was identified as Streptomyces sp. by analysis of 16S rDNA. On the test with pepper fruits, the strain inhibited disease incidences of late blight and anthracnose over 80%. In greenhouse test, plant height, the number of leaf, fresh weight and roots length of pepper plants upon treatment of culture suspension of Streptomyces sp. MG 121 were significantly higher than those without the bacterial cells. In addition, strain MG 121 was capable to solublize rock-phosphate after incubation for 144 hours in potato dextrose broth. The concentration of soluble phosphate in PDB amended with 0.5% rock-phosphate was increased up to $765{\mu}g/ml$.

• Korean Journal of Microbiology
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• v.38 no.1
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• pp.1-6
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• 2002

$\alpha$-Amylase producing bacteria were isolated from activated sludge of corn processing wastewater plant and paddy field soil samples and selected by the direct iodine reaction. The isolate was identified as Bacillus sp. after morphology, API system and fatty acid analyses. To enchance $\alpha$-amylase productivity, a successive mutation of Bacillus sp. AIV 19 was performed using the treatment of nitrosoguanidine(NTG).The mutant, Bacillus sp. AIV 1940, showed about 1.8-fold level of amylase activity compared with parental strain. The isolate was Gram-positive and rod (2.8-3.0 $\mu$m long, 0.5-0.6 $\mu$m wide) type. The strain increased the bacterial mass at 3000 mg/l starch concentration. Organic substance removal rate was 40.2, 72.3% respectively after 1 and 3 day reaction using starch synthetic wastewater (intial CODcr was 4,455 mg/l).

• Journal of Life Science
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• v.24 no.6
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• pp.694-699
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• 2014

Indigenous microorganisms play decisive roles in biodegradation. In this study, eighty strains of hydrocarbon-degrading microbes were isolated from Incheon Bay. Among them, 12 strains were selected by an oil film collapsing method. The bacterial strain 'Incheon9' was eventually selected based on its relatively higher lipase and emulsification activities, and was identified as Acinetobacter sp. (NCBI accession code: KF54854). The optimum condition for the growth and emulsification activity of Acinetobacter sp. Incheon9 was $20^{\circ}C$, pH 7, and 1% NaCl. The optimum time for the best production of biosurfactant was 72 hrs. The oil degradation ability of Acinetobacter sp. Incheon9 was investigated by measuring the residual oils in the culture medium by gas chromatography (FID). This research provides foundational data for eco-friendly environmental remediation by microorganisms.

• Korean Journal of Environmental Agriculture
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• v.30 no.3
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• pp.346-356
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• 2011

BACKGROUND: Chemical fungicides not only may pollute the ecosystem but also can be environmentally hazardous, as the chemicals accumulate in soil. Biological control is a frequently-used environment-friendly alternative to chemical pesticides in phytopathogen management. However, the use of microbial products as fungicides has limitations. This study isolated and characterized a three-antifungal-enzyme (chitinase, cellulase, and ${\beta}$-1,3-glucanase)-producing bacterium, and examined the conditions required to optimize the production of the antifungal enzymes. METHOD AND RESULTS: The antifungal enzymes chitinase, cellulase, and ${\beta}$-1,3-glucanase were produced by bacteria isolated from an sawmill in Korea. Based on the 16S ribosomal DNA sequence analysis, the bacterial strain AM50 was identical to Streptomyces sp. And their antifungal activity was optimized when Streptomyces sp. AM50 was grown aerobically in a medium composed of 0.4% chitin, 0.4% starch, 0.2% ammonium sulfate, 0.11% $Na_2HPO_4$, 0.07% $KH_2PO_4$, 0.0001% $MgSO_4$, and 0.0001% $MnSO_4$ at $30^{\circ}C$. A culture broth of Streptomyces sp. AM50 showed antifungal activity towards the hyphae of plant pathogenic fungi, including hyphae swelling and lysis in P. capsici, factors that may contribute to its suppression of plant pathogenic fungi. CONCLUSION(S): This study demonstrated the multiantifungal enzyme production by Streptomyces sp. AM50 for the biological control of major plant pathogens. Further studies will investigate the synergistic effect, to the growth regulations by biogenic amines and antifungal enzyme gene promoter.

• Journal of fish pathology
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• v.12 no.1
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• pp.42-48
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• 1999

The disinfectant effects of total residual oxidants (TROs) produced by ozonization of natural sea water were investigated against fish pathogenic bacteria isolated from flounder and red seabream. The concentration of 0.1 mg TROs/liter was stable for 20 min in filtered natural seawater, and those of 0.3 and 0.5 mg TROs/liter were also stable for more 1 hr. Disinfectant effects of TRO against Edwardsiella tarda, Vibrio sp., Streptococcus sp. and Staphylococcus sp. were observed with a concentration of 0.1 mg/liter for 180 sec, and the treatment killed more than 99.9% of bacterial cells. With TROs of 0.3 to 0.5 mg/ liter, the viable cells of the bacteria were reduced by more than 99.99% in 60 sec.

• Microbiology and Biotechnology Letters
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• v.49 no.4
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• pp.543-551
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• 2021

Nocardiopsis species produce bioactive compounds, such as antimicrobial and anti-cancer agents and toxins. However, no reports have described their anti-inflammatory and anti-fibrotic effects during nasal polyp (NP) formation. In this study, we investigated whether marine-derived bacterial Nocardiopsis sp. 13G027 exerts anti-inflammatory and anti-fibrotic effects on lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages and transforming growth factor (TGF)-β1-induced NP-derived fibroblasts (NPDFs). Nitric oxide (NO) and prostaglandin E₂ (PGE₂) levels were analyzed. Extract from Nocardiopsis sp. 13G027 significantly inhibited the upregulation of NO and PGE₂ in LPS-activated RAW 264.7 macrophages. The expression of mitogen-activated protein kinases (MAPKs) and protein kinase B (Akt/PKB) in LPS-induced RAW 264.7 macrophages was evaluated; smooth muscle alpha-actin (α-SMA), collagen type I (Col-1), and fibronectin also phosphorylated small mothers against decapentaplegic (SMAD) 2 and 3 in TGF-β1-stimulated NPDFs. The Nocardiopsis sp. 13G027 extract suppressed the phosphorylation of MAPKs and Akt and the DNA-binding activity of activator protein 1 (AP-1). The expression of pro-fibrotic components such as α-SMA, Col-1, fibronectin, and SMAD2/3 was inhibited in TGF-β1-exposed NPDFs. These findings suggest that Nocardiopsis sp. 13G027 has the potential to treat inflammatory disorders, such as NP formation.

• Microbiology and Biotechnology Letters
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• v.52 no.2
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• pp.135-140
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• 2024

This study reports the isolation of a bacterium capable of degrading agar and the characterization of its agarase. An agar-degrading marine bacterium JS-1 was isolated using Marine agar 2216 media from seawater collected from the seashore of Angolpo, Changwon, Gyeongnam Province, Republic of Korea. An agar-degrading bacterium was named as Tenacibaculum sp. JS-1 by phylogenetic analysis based on 16S rRNA gene sequence. The extracellular crude agarase was prepared from the culture media of Tenacibaculum sp. JS-1 and used for characterization. Relative activities at 20, 30, 40, 50, and 60℃ were 39, 73, 100, 74, and 53%, respectively. Relative activities at pH 5, 6, 7, and 8 were 46%, 67%, 100%, and 49%, respectively. Its extracellular agarase showed maximum activity (164 U/l) at pH 7.0 and 40℃ in a 20 mM GTA buffer. The residual activities after heat treatment at 20, 30, and 50℃ for 30 min were 84, 73, and 26% or more, respectively. After 2 h heat treatment at 20, 30, 40, and 50℃, the residual activities were 80, 64, 52 and 21%, respectively. Thin layer chromatography analysis suggested that Tenacibaculum sp. JS-1 produces extracellular β-agarases that hydrolyze agarose to produce neoagarooligosaccharides, including neoagarohexaose (12.3%), neoagarotetraose (65.1%), and neoagarobiose (22.6%) at 6 h. Tenacibaculum sp. JS-1 and its β-agarase could be valuable for producing neoagarooligosaccharides with a variety of functional properties. These properties include inhibiting bacterial growth, slowing down starch degradation, and whitening, which are of interest for pharmaceuticals, food, cosmeceuticals, and nutraceuticals.

• Applied Microscopy
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• v.45 no.4
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• pp.249-253
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• 2015

Microorganisms specifically groups of bacteria exhibiting physiological activities of production of acids are a major cause of concern because of their ability to induce corrosion in oil field pipelines and metal systems involved in water handling. Water Injection Stations as a means of secondary recovery from existing oil producing reservoirs, are often employed in most upstream oil and gas industries to ensure replenishment of voidage, maintenance of reservoir pressure and optimization of crude emulsion throughput. In the present study, scanning electron microscopy of macroscopic orange coloured slime formations sampled from leaking valves on the flow-lines of a Water Injection Stations of Oil India Limited revealed the presence of filamentous bacterial mats in association with diatoms. The species composition of the acidic slime formations from the sampled locations reveal the possible role of acid producing iron oxidizing bacteria (IOB) like Acidithiobacillus ferrooxidans in association with Gomphonema sp. in creating conditions for bio-corrosion.