• Korean Journal of Microbiology
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• v.34 no.3
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• pp.87-90
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• 1998

Various bacterial strains that secret extracellular fibrinolytic enzyme were screened from Doen-Jang, a traditional soybean fermented food in Korea. Five microbes of them were identified to be Bacillus sp. strains according to Bergey's manual of systematic bacteriology. The culture filtrates of B. amyloliquefaciens (2.46 plasmin unit/ml) and B. pantothenticus (3.82 plasmin unit/ml) showed a level of fibrinolytic activity that was about three times higher than that of plasmin 1.0 unit and Bacillus subtilis showed the highest fibrinolytic activity (4.94 plasmin unit/ml). All of the extracellular proteases showing the fibrinolytic activity are confirmed by SDS-PAGE followed by reverse fibrin zymogram activity assay and we proposed that some of the fibrinolytic enzymes from this work are novel enzymes.

• Microbiology and Biotechnology Letters
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• v.2 no.1
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• pp.19-27
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• 1974

Thirty one culture filtrates of Penicillium app. isolated from foodstuffs were submitted for toxicity by use of HeLa cell and ICR-mice. Nine strains among the 31 of Penicillia were cytotoxic to the HeLa cell cultures. Seven strains among the 31 of Penicillia were toxic to the ICR-mice and the pathological findings were the liver injury featured by parenchymal cell necrosis and degeneration. As a mass screening, cytotoxicity test using HeLa cells is feasible method to detect the mycotoxin-producing fungi.

• The Journal of the Korean Society for Microbiology
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• v.12 no.1
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• pp.33-49
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• 1977

These studies were carried out to detect the presence of mycotoxin fungi and detoxification of toxins in various kinds of grain and foodstuffs in Korea. The experiments were divided into three parts: mycologic, toxicologic and electron microscopic study. The resuIts were summarized as follows: 1. From the 210 various, samples(local grains, 150 samples; rice-cakes, 50 samples; meju, 10 samples), 1,205 colonies or fungi were isolated. In 1,127 of 1,205 colonies, it was possible to identify 21 genera. Among the identified strains, the predominant genera were Aspergillus sp.(28.5%), Penicillium sp.(27.1%) and Mucor sp.(7.8%). 2. In cytotoxicity test on HeLa cells, 25 strains showed severe toxic effects among the 240 strains of experiments. 3. In histopathologic test on mice, 21 strains showed severe toxic effect to mouse liver cells among the 240 tested strains. 4. In electron microscopic studies of HeLa cells and mouse liver cells from animal which had been treated with crude toxin, the liver cells showed the cytoplasmic change: dillatation or vacuolization of endoplasmic reticulum, swelling of mitochondria and disappearance of mitochondrial cristae, increased number of lipid and glycogen particles. Nucleus and nucelar envelope alterations, were also noted. 5. In the detoxification study with ultraviolet irradiation, 90% of the toxic substances were denatured by the ultraviolet light irradiation for 24 hours. 6. As a mass screening, the cytotoxicity test of HeLa cells and histopathologic study of mice liver cells treated with culture filtrates, employed and feasible to detect mycotoxin producing fungi.

• Journal of Microbiology and Biotechnology
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• v.17 no.4
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• pp.586-593
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• 2007

Seed coating by a phenazine-producing bacterium, Pseudomonas chlororaphis O6, induced dose-dependent inhibition of germination in wheat and barley seeds, but did not inhibit germination of rice or cucumber seeds. In wheat seedlings grown from inoculated seeds, phenazine production levels near the seed were higher than in the roots. Deletion of the gacS gene reduced transcription from the genes required for phenazine synthesis, the regulatory phzI gene and the biosynthetic phzA gene. The inhibition of seed germination and the induction of systemic disease resistance against a bacterial soft-rot pathogen, Erwinia carotovora subsp. carotovora, were impaired in the gacS and phzA mutants of P chlororaphis O6. Culture filtrates of the gacS and phzA mutants of P. chlororaphis O6 did not inhibit seed germination of wheat, whereas that of the wild-type was inhibitory. Our results showed that the production of phenazines by P. chlororaphis O6 was correlated with reduced germination of barley and wheat seeds, and the level of systemic resistance in tobacco against E. carotovora.

• Journal of the Korean Wood Science and Technology
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• v.26 no.3
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• pp.53-62
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• 1998

In this research, 7 species of white rot fungi were used for determining the resistance against pentachlorophenol (PCP). Three fungi with good PCP resistance were selected for evaluating the biodegradability, and biodegradation mechanism by HPLC and GC/MS spectrometry. Among 7 fungi, there were significant differences on PCP resistance on 4 different PCP concentrations. In the concentrations of 50 and 100ppm ($\mu$g of PCP per g of 2% malt extract agar), most fungi were easily able to grow, and well suited to newly PCP-added condition, but in that of more than 250ppm, the mycelia growths of Ganoderma lucidum 20435, G. lucidum 20432, Pleurotus ostreatus, and Daldinia concentrica were significantly inhibited or even stopped by the addition of PCP to the culture. However, Trametes versicolor, Phanerochaete chrysosporium, and Inonotus cuticularis still kept growing at 250ppm, indicating the potential utilization of wood rot fungi to high concentrated PCP biodegradation. Particularly, P. chrysosporium even showed very rapid growth rate at more than 500ppm of PCP concentration. Three selected fungi based on the above results showed an excellent biodegradability against PCP. P. chrysosporium degraded PCP up to 84% on the first day of incubation, and during 7 days, most of added PCP were degraded. T. versicolor also showed more than 90% of biodegradability at 7th day, and even though the initial stage of degradation was very slow, I. cuticularis has been approached to 90% at 21 st day after incubation with dense growing pattern of mycelia. Therefore, the PCP biodegradability was definitely dependent on the rapid suitability of fungi to newly PCP-added condition. In addition, the PCP biodegradation by filtrates of P. chrysosporium, T. versicolor, and I. cuticularis was very minimal or limited, suggesting that the extracellular enzyme system may be not so significantly related to the PCP biodegradation. Among the biodegradation metabolites of PCP, the most abundant one was pentachloroanisole which resulted in a little weaker toxicity than PCP, and others were tetrachlorophenol, tetrachloro-hydroquinone, benzoic acid, and salicylic acid, suggesting that PCP may be biodegraded by several sequential reactions such as methylation, radical-induced oxidation, dechlorination, and hydroxylation.

• Journal of the Korean Wood Science and Technology
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• v.26 no.3
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• pp.63-72
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• 1998

In order to evaluate the biodegradability and mechanism of 4,5,6-trichloroguaiacol (TCG) produced from bleaching process in pulp mill by Phanerochaete chrysosporium, Trametes versicolor, and Inonotus cuticularis, changes in TCG and its metabolites during biodegradation were analyzed by HPLC, and GC/MS spectrometry. By three fungi, the maximum biodegradability against TCG were very quickly reached, compared with other chlorinated aromatic compounds such as PCP. Within 24 hrs, T versicolor indicated up to 95% of TCG removal rate, and P. chrysosporium and I. cuticularis also showed more than 80%, and 90%, respectively. Particularly, in case of T. versicolor, the removal rate of TCG after 1 hr. incubation was reached to approximately 90%, implying very rapid metabolization of TCG. However, by analyzing the filtrates extracted from TCG containing culture by GC/MS, the major metabolites at initial stage of biodegradation were dimers, indicating that the added TCG monomers were quickly polymerized. The others were trichloroveratrole, dichloroguaiacol, and trichlorobenzoic acid, suggesting that TCG may be biodegraded by several sequential reactions such as polymerization, oxidation, methylation, dechlorination, and hydroxylation. In other experiments, the extracellular fluid which did not contain any fungal mycelia was used to evaluate the effect of mycelia on TCG biodegradation. The extracellular fluid of T. versicolor also biodegraded TCG up to 90% within 24hrs, but those of P. chrysosporium and I. cuticularis did not show any good biodegradability. T versicolor showed the highest value of laccase, and other two fungi indicated a little activity of lignin peroxidase (LiP) and manganese peroxidase (MnP). In addition, the laccase activity of T. versicolor was very linearly proportional to the removal rate of TCG during incubation, in other words, showing the induction effect against TCG. Consequently, the biodegradation of TCG was very dependent upon the activity of laccase.

• Korean Journal of Microbiology
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• v.51 no.2
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• pp.108-114
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• 2015

We tried to analyze the growth time for secretion of the iron containing superoxide dismutase by comparing the intra-and extracellular enzyme activity from Streptomyces subrutilus P5 and analyze possible genetic information for this enzyme secretion. The mycelial dry weights and glucose concentrations in culture filtrates were determined during growth. Glucose was consumed rapidly during logarithmic growth phase and almost exhausted at 24 h of cultivation. While the intracellular activity of iron containing superoxide dismutase was first appeared at three hours, the extracellular activity of this enzyme appeared from 7.5 h of cultivation, early logarithmic growth phase. This early presence of the superoxide dismutase might not be the result of cell lysis but active secretion pathway. There was no information for signal peptide responsible for the enzyme secretion in sodF. However, we found a type three secretion box in the promoter region of sodF that has been known for the genes of type III secreted proteins in other bacteria. This is the first report on the possible existence of type III secretion in Streptomyces.

• The Korean Journal of Mycology
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• v.10 no.2
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• pp.67-73
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• 1982

The $(NH_4)_2\;SO_4$ (70%) treated crude enzymes from the culture filtrates of the$C-7^{+t}$ strain of Pyricularia oryzae which was grown on 2% CMC (carboxymethyl cellulose) for 8 days at $28^{\circ}C$ were chromatographied on Sephadex G-150 and DEAE-Sephadex A-25 columns. From the chromatography, three fractions of CMCase$(C_x)$ was examined using Na-CMC as substrate. The $C_x$ enzyme activity was optimal at pH 6.0 and $40^{\circ}C$, stable up to $40^{\circ}C$. The values of Km and Vmax of the enzyme were $2.8{\times}10\;mM$ and 5.9m moles/hour, respectively. The molecular weight determined by Sephadex G-150 column chromatography was around 80,000. Approximately sevenfold purified $C_x$ enzyme gave a single protein band on the polyacrylamide gel electrophoresis.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2010.10a
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• pp.18-18
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• 2010

Molecular insights on the role of plant growth promoting rhizobacteria (PGPR) in potato tuberization are reported in the present study. The PGPRwere isolated from the soil collected from potato fields of Highland Agricultural Research Centre, Pyeongchang, Korea and they were identified to the genus level based on the 16S rRNA sequence analysis. These PGPR were heat-killed, filtered and the filtrates were addedindividually at a concentration of $10^7\;cfu\;mL^{-1}$ in MS (Murashige and Skoog's) medium supplemented with 7% (w/v) sucrose to study their influence on in vitro potato tuberization. Tuber initiation occurred early in untreated control, while tuber growth was pronounced in case of PGPR treatments. The control explants showed tuber formation as a result of sub-apical swelling of stolons while several sessile tubers formed directly in the axils of nodal cuttings in case of PGPR treatments, which is an indication of strong induction for tuberization. Theexplants cultured on MS medium supplemented with bacterial isolate 6 (Bacillus firmus strain 40) showed highest average tuber yield (Ca. 12.56 g per treatment) after 30 days of culture, which was 3 folds increase over the untreated control. A significant increase in lipoxygenase (LOX1) mRNA expression and activity of LOX enzyme were also detected in the tubers induced on PGPR treatments as compared to untreated control. This LOX expression level correlated with increased tuber growth and tuber yield. Further studies focused on the role of bacteria cell wall components, growth regulators and signal molecules released by PGPR are under investigation to elicit clues for PGPR-mediated signal pathway controlling potato tuberization.

• Journal of Microbiology and Biotechnology
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• v.20 no.12
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• pp.1744-1749
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• 2010

The role of endophytic fungi in plant growth and development is well documented. However, endophytic fungi with growth promotion capacity have never been isolated from weeds previously. In the current study, we isolated 8 fungal endophytes from the roots of Monochoria vaginalis, a serious weed of rice paddy in Korea. These isolates were screened on Waito-C, in order to identify plant growth promoting metabolites. Two fungal isolates (M5.A & M1.5) significantly promoted the plant height and shoot length of Waito-C during preliminary screening experiments. The culture filtrates (CFs) of M5.A and M1.5 also promoted the shoot length of Echinocloa crusgalli. Gibberellins (GAs) analysis of the CFs of M5.A and M1.5 showed that these endophytic fungi secrete higher quantities of GAs as compared with wild-type G. fujikuroi KCCM12329. The CF of M5.A contained bioactive GAs ($GA_3$, 2.8 ng/ml; $GA_4$, 2.6 ng/ml, and $GA_7$, 6.68 ng/ml) in conjunction with physiologically inactive $GA_9$ (1.61 ng/ml) and $GA_{24}$ (0.18 ng/ml). The CF of M1.5 contained physiologically active GAs ($GA_3$, 1.64 ng/ml; $GA_4$, 1.37 ng/ml and $GA_7$, 6.29 ng/ml) in conjunction with physiologically inactive $GA_9$ (3.44 ng/ml), $GA_{12}$ (0.3 ng/ml), and $GA_{24}$ (0.59 ng/ml). M5.A and M1.5 were identified as new strains of Penicillium sp. and Aspergillus sp., respectively, based on their 18S rDNA sequence homology and phylogenetic analysis.