• Journal of Food Hygiene and Safety
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• v.16 no.4
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• pp.274-279
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• 2001

Generally, non-aflatoxigenic fungi, such as Aspergillus oryzae, and Aspergillus are main microflora in Korean traditional fermented foods including Meju and soybean paste, but sometimes, Aspergillus flavus and Aspergillus parasiticus can be contaminated and accumulated aflatoxins during fermentation and storage. So the screening of aflatoxigenic strains in fermented traditional food is very important to improve the sanitary quality of those foods. In this work, we screened aflatoxin producing fungi from commercial Meju and soybean paste in Western Gyeongnam by immunoassay. Samples were randomly purchased from market of the commercial Meju(10 EA) and soybean paste(20 EA) in nine areas of Western Gyeongnam. Of the samples collected,24 strains and 22 strains of Aspergillus sp. were isolated from Meju and soybean paste, respectively. The isolated strains were cultured on SLS media at $25^{\circ}C$ for 15 days. The cultured broth were extracted with ethyl acetate and were analysed to determine aflatoxin B$_1$(AFB$_1$) by direct competitive ELISA(DC-ELISA). Six strains(25%) isolated from Meju, and 2 strains(9%) isolated from saybean paste, were confined as aflatoxin producing strains. The average range of aflatoxin productivity of isolates from Meju was 54.6 $\pm$ 38.7 ng/ml and that from soybean paste was 11.1 $\pm$ 8.6 ng/ml, respectively. Among them, isolated strain No. M-5-4 produced a high level of AFBl and showed 98.26 ng/ml of AFB$_1$. Every isolates were also re-confined their AFB$_1$productivity by thin layer chromatography(TLC). The TLC results also showed same trend as DC-ELISA results. As the above results, the screening of hazard mycotoxigenic fungi from traditional fermented foods should be necessary for the safety and the application of HACCP system in the food manufactory in Korea.

• Korean journal of applied entomology
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• v.24 no.2 s.63
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• pp.107-114
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• 1985

This experiment was performed to see the possibility if soil-borne disease in green house can be controlled by soil solarization in Korea. Thermal death profiles of propagules of some soil-borne fungi, Fusarium oxysporum f. lycopersici, Fusarium oxysporum f. niveum, Rhizoctonia salani, Sclerotinia sclerotiorum, Sclerotium rolfsii and Pythium debaryanum, were obtained under the conditions in water-suspension and in soil. Except Pythium debaryanum, all the fungal units in water-suspension that were colonized on barley grains lost a viability within 7 days in water bath at $45^{\circ}C$. When the soil in test tubes in which barley grains infected with the fungi were also buried all the fungi tested including Pythium debaryanum were completely killed within 7 days in water bath at $45^{\circ}C$. From July to August in Korea, soil temperature at depth of 5cm and 15cm within tunnel in plastic house reached $38^{\circ}C\;to\;57^{\circ}C$ and $40^{\circ}C\;to\;47^{\circ}\C$, in 1982 and 1983 respectively. Even at 15cm depth, soil temperature were kept over $43^{\circ}C$ for 12 hours a day. Adiabatic material set under ground or under mulching with the transparent polyethylene-film on the soil surface had a boostering effect for higher soil-temperature and longer duration. Fungi buried in adiabatic block of the soil in plastic house were completely killed at 15cm depth 14 days after, and at 20cm depth 21 days after soil solarization. The exposure of the pathogens to fluctuating temperature was much more effective than to constant. From the above results, soil-borne diseases may be effectively controlled by soil solarization in the closed plastic house in hot summer season in Korea.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.4
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• pp.195-203
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• 2006

An antagonistic strain, Burkholderia MP-1, showed antimicrobial activity against various filamentous plant pathogenic fungi, yeasts and food borne bacteria (Gram-positive and Gram-negative). The nucleotide sequence of the 16S rRNA gene (1491 pb) of strain MP-1 exhibited close similarity (99-100%) with other Burkholderia 16S rRNA genes. Isolation of the antibiotic substances from culture broth was fractionated by ethyl acetate (EtOAc) solvent and EtOAc-soluble acidic fraction. The antibiotic substances were purified through a silica gel, Sephadex LH-20, ODS column chromatography, and high performance liquid chromatography, respectively. Four active substances were identified as phenylacetic acid, hydrocinnamic acid, 4-hydroxyphenylacetic acid and 4-hydroxyphenylacetate methyl ester by gas chromatographic-mass spectrum analysis. The minimum inhibition of concentration (MIC) of each active compound inhibited the growth of the microorganisms tested at 250 to $2500{\mu}g\;ml^{-1}$. The antimicrobial activity of crude acidic fraction at 1 mg of dry weight per 6 mm paper disc was more effective than authentic standard mixture (four active substances were mixed with the same ratio as acidic fraction) over a wide range of bacterial test.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.2
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• pp.196-199
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• 1997

We studied the effect of inoculation of microorganisms known to produce plant growth promoting substances, on the growth and yield of cucumber(Cucumis sativa L.), through a field experiment. The microorganisms used were isolated from the forest soil and consisted of Micrococus sp., Baccilus sustilis, Enterobacter agglomerans, Baccilus megaterium, Pseudomonas putida, Cellulomonas sp. and Staphylococus xyposus. Fotr the multiplication, microorganisms were cultured in liquid media of Pseudomonas P and Sabouraud dextrose. Inoculation of microorganisms was done by spraying the culture media after the culture of them to soil and cucumber plants, three times during the growth of cucumber at the rate of 10l/ha. The inoculation of microorganisms tended to promote the growth of cucumber plant and increase the yield of it. No sign of significant improvement of soil chemical and physical properties were observed after the harvest of crop. The population of bacteria and actinomycetes tended to be higher in the inoculated plots than in not inoculated plots, while opposite was the case in the population of fungi.

• Microbiology and Biotechnology Letters
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• v.38 no.1
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• pp.77-83
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• 2010

The fructus of Crataegus pinnatifida Bunge (CBF) has been used as medicinal and food source in worldwide. In this study, antimicrobial activity of the methanol extract and its sequential organic solvent fractions of CBF against different pathogenic bacteria and fungi, including multidrug resistant Pseudomonas aeruginosa and Candida sp., were investigated. The methanol extract of CBF was active against various gram-positive and gram-negative bacteria, and the ethylacetate and butanol fractions of CBF showed strong antibacterial activity against Listeria monocytogenes, Staphylococcus epidermidis, Staphylococcus aureus, Bacillus subtilis, Salmonella typhimurium, Proteus vulgaris, Escherichia coli and various multidrug resistant Pseudomonas aeruginosa with minimal inhibitory concentration of 1.0~7.5 mg/mL. Also the fractions showed anti-Candida activity against C. albicans, C. kruseis and C. geochares. The methanol extract of CBF and its solvent fractions, except n-hexane fraction, did not show any hemolytic activity against human red blood cell up to $500\;{\mu}g/mL$, respectively. The hemolysis in n-hexane fraction at $500\;{\mu}g/mL$ was less than 9.9%. Our results suggest that the CBF could be developed as a potent antibacterial agent, especially for multidrug resistant Pseudomonas aeruginosa.

• Korean journal of applied entomology
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• v.23 no.2 s.59
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• pp.82-88
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• 1984

Fruit rot and blister canker, a disease of apple occurring severely in Korea has been studied for correct identification of the syndrome In fruit and apple trees. Among the fungi isolated from blister cankers, rough barks or fruits showing rotting of 7 different host species were Botryosphaeria berengeriana (pycnidial stage. Dethiorella mali), Penicillium expansum and Alternaria sp. from apple rots and Phomopsis sp. from pear fruit rots. The most dominant isolates were B. berengeriana. Ten isolates of D. mali were grouped in to two conidial types based up mycelial growth rate, growth habits and mycelial coloration on PDA. None of 10 isolates was chromogenic. Pycnidia in apple stems, stromatic, dark brown, globose or subglobose and the measuring were $103.5-287.5{\mu}\times92.0-287.5\mu$. The pycnidia contained hyaline, nonseptate, fusiform conidia. The sizes of pycnidiospore of isolates obtained from apple twig were $4.3-7.2{\mu}\times20.0-31.5{\mu}(average\;5.9\times25.4\mu)$. Some conidia of this fungus from apple, pear, peach and ornamental cherry showed 1-,2-,3-septate before or during germination. Microconidia were observed in pycnidia on PDA and fruit lesion of inoculated host. Symptoms on leaves and fruits were contoured brown spots when inoculated. Wart-like protuberance were formed on the surface of apple and pear. Canker appeared on branches of peach and ornamental cherry inoculated.

• BMB Reports
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• v.39 no.1
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• pp.105-110
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• 2006

We have screened 766 strains of fungi from the BIOTEC Culture Collection (BCC) for xylanases working in extreme pH and/or high temperature conditions, the so-called extreme xylanases. From a total number of 32 strains producing extreme xylanases, the strain BCC7928, identified by using the internal transcribed spacer (ITS) sequence of rRNA to be a Marasmius sp., was chosen for further characterization because of its high xylanolytic activity at temperature as high as $90^{\circ}C$. The crude enzyme possessed high thermostability and pH stability. Purification of this xylanase was carried out using an anion exchanger followed by hydrophobic interaction chromatography, yielding the enzyme with >90% homogeneity. The molecular mass of the enzyme was approximately 40 kDa. The purified enzyme retained broad working pH range of 4-8 and optimal temperature of $90^{\circ}C$. When using xylan from birchwood as substrate, it exhibits $K_m$ and $V_{max}$ values of $2.6{\pm}0.6\;mg/ml$ and $428{\pm}26\;U/mg$, respectively. The enzyme rapidly hydrolysed xylans from birchwood, beechwood, and exhibited lower activity on xylan from wheatbran, or celluloses from carboxymethylcellulose and Avicel. The purified enzyme was highly stable at temperature ranges from 50 to $70^{\circ}C$. It retained 84% of its maximal activity after incubation in standard buffer containing 1% xylan substrate at $70^{\circ}C$ for 3 h. This thermostable xylanase should therefore be useful for several industrial applications, such as agricultural, food and biofuel.

• Microbiology and Biotechnology Letters
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• v.25 no.6
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• pp.592-597
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• 1997

During the screening of inhibitors against phospholipase C (PLC) and the formation of inositol phosphates (IP$_{t}$) at NIH3T3${\gamma}$1 cells from microbial secondary metabolites, we selected a fungal strain MT60109 which was capable of producing an inhibitor. By the taxonomic studies, this fungus was identified as Pseudallescheria sp. MT60109 and an inhibitor of PLC was purified by BuOH extraction and chromatographic techniques from the culture broth of Pseudallescheria sp. MT60109. The inhibitor was identified as thielavin B by the physico-chemical properties and spectroscopic analysis of UV, FAB-MS, $^{1}$H, $^{13}$C-NMR, $^{1}$H-$^{1}$H COSY and HMBC. Thielavin B showed potent inhibitory activity against PLC purified from bovine brain with an IC$_{50}$ of 20 $\mu$M. And it also inhibited the formation of inositol phosphates in platelet-derived growth factor (PDGF) -stimulated NIH3T3${\gamma}$1 cells with an IC$_{50}$ of 20 $\mu$M.

• Microbiology and Biotechnology Letters
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• v.10 no.1
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• pp.33-37
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• 1982

The work has been carried out for the development of antifungal antibiotics possessing curative effect in the control of sheath blight disease of rice plant. Soil samples were collected from over 1600 spots throughout the country. More than 1300 specimens which seem to be the genus Streptomyces were isolated from the soil samples. Screening procedures consist of respective processes by four steps. Those are growth inhibition test in liquid culture, paper disk method, dendroid test and green house test. 102 isolates appeared to be active against Pellicularia sasakii when all specimens isolated were examined by the first growth inhibition test. Finally a strain of Streptomyces forming strong antifungal substances against P. sasakii was selected from a soil sample of Mt. Soyo, Kyeongi Province. Antifungal substances formed by the strain were isolated and purified from the culture broth and examined for antimicrobial activities as to be specific against fungi but not active on bacterial growth.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2006.11a
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• pp.285-289
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• 2006

In screening of algicidal bacteria, we isolated a marine bacterium which had potent algicidal effects on harmful algal bloom (HAB) species. This organism was identified as a strain very close to Bacillus subtilisby 16S rRNA gene sequencing. This bacterium, Bacillus sp. SY-1, produces very active algicidal compounds against the harmful dinoflagellate Cochlodinium polykrikoides. We isolated three algicidal compounds (MS 1056, 1070, 1084) and identified them by amino acid analyses, fast atom bombardment mass spectrometry (FAB-MS), infrared spectroscopy (IR), $^1H$, $^{13}C$, and extensive two-dimensional nuclear magnetic resonance (2D NMR) techniques including $^1H-^{15}N$ HMBC analysis. One of them, MS 1056, contains a b-amino acid residue with an alkyl side chain of $C_{15}$. MS 1056, 1070, and 1084 showed algicidal activities against C. polykrikoides with an $LC_{50}$ (6 hrs) of 2.3, 0.8, $0.6\;{\mu}g/ml$, respectively. These compounds also showed significant algicidal activities against other harmful dinoflagellates and raphidophytes. In contrast, MS 1084 showed no significant growth inhibition against various organisms coexisting with HAB species in natural environments, including bacteria, eukaryotic microalgae, and cyanobacteria, although it inhibited growth of some fungi and yeasts. These observations imply that algicidal bacterium Bacillus sp. SY-1 and its algicidal compounds could play an important role in regulating the onset and development of HABs in the natural environments.