• Microbiology and Biotechnology Letters
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• v.23 no.2
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• pp.209-213
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• 1995

During the screening of inhibitors of melanin biosynthesis from microbial secondary metabolites, a fungal strain MR-93 which was capable of producing high level of an inhibitor was selected from plant leaf. Based on taxonomic studies, the fungus could be classified as a strain of Trichoderma sp.. The active compound (MR-93D) was purified from the culture broth by Diaion HP-20 column chromatography, ethylacetate extraction, Sephadex LH-20 column chromatography and HPLC. The inhibitor was identified as 4-hydroxy-8-isocyano-l-oxaspiro[4-4]cyclonon-8-en-2- one by spectroscopic methods of UV, $^{1}$H-NMR, ESIMS and IR. MR-93D showed a strong tyrosinase inhibitory activity with 0.03 $\mu$g/m of IC$_{50}$ value. It also inhibited melanin biosynthesis with 35 mm inhibition zone at 30 $\mu$g/paper disc in Streptomyces bikiniensis, a bacterium used as an indicator organism in this work.

• Current Research on Agriculture and Life Sciences
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• v.20
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• pp.49-54
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• 2002

This study was conducted to investigate physicochemical and microbiological properties on waste composts of mushroom. The waste compost of mushroom consisted of 43.29% organic matter(O.M.), 27.0 O.M./Nitrogen, 1.60% total nitrogen, 46.48% water content, 0.64% salt content, 1.32% $P_2O_5$ 1.18% $K_2O$ and dry base. The microorganisms in the waste compost of mushroom were counted $1.6{\times}10^{10}cfu/g$. The main population of aerobic bacteria were Bacillus lentimobus, B. coagulans, B. brevis, Clostridium thermocellum, Escherichia coli, Streptomyces thermovulgaris, S. thermofuscus, Micropolyspora faeni, Aspergillus sp. and Penicillum sp..

• Journal of Microbiology and Biotechnology
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• v.20 no.5
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• pp.875-880
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• 2010

Bacterial enoyl-ACP reductase (FabI) has been demonstrated to be a novel antibacterial target. In the course of our screening for FabI inhibitors, we isolated two methyl-branched fatty acids from Streptomyces sp. A251. They were identified as 14-methyl-9(Z)-pentadecenoic acid and 15-methyl-9(Z)-hexadecenoic acid by MS and NMR spectral data. These compounds inhibited Staphylococcus aureus FabI with $IC_{50}$ values of 16.0 and $16.3\;{\mu}M$, respectively, but did not affect FabK, an enoyl-ACP reductase of Streptococcus pneumonia, at $100\;{\mu}M$. Consistent with their selective inhibition for FabI, they blocked intracellular fatty acid synthesis as well as the growth of S. aureus, but did not inhibit the growth of S. pneumonia. Additionally, these compounds showed reduced antibacterial activity against fabI-overexpressing S. aureus, compared with the wild-type strain. These results demonstrate that the methylbranched fatty acids show antibacterial activity by inhibiting FabI in vivo.

• Microbiology and Biotechnology Letters
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• v.6 no.4
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• pp.149-153
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• 1978

A strain of Streptomyces sp producing chitinase was isolated from soil and its cultural condition and some properties of this enzyme were investigated. When 0.375 per cent of glucose was added to basal medium, this organism produced the most quantities of this enzyme after shaking culture at 3$0^{\circ}C$ for 48 hrs., while the production of the enzyme was repressed at the more concentration of glucose than that. The enzyme had a optimal pH of 7.0, optimal temperature of 5$0^{\circ}C$ and the activity of that was not decreased by heat treatment for 20 minute at 7$0^{\circ}C$. And then the activity was increased by Co$^{2+}$ but was slightly inhibited by Hg$^{2+}$, Ni$^{2+}$, Pb$^{2+}$.EX> 2+/.

• Journal of the Korean Magnetic Resonance Society
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• v.6 no.1
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• pp.69-77
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• 2002

During the screening of material which has the antimicrobial activity against aminoglycoside-resistant bacteria, A new material $\varepsilon$-(L-$\beta$-Iysine) polypeptide from a culture medium of Streptomyces sp.(DWGS2) was isolated, and the structure and the physicochemical properties of the new material were elucidated. The new material was separated by column chromatography of the culture medium using Dowex1$\times$2, Silica gel, and Sephadex LH20 etc. The chemical structure and molecular weight were determined with the data of various NMR experiments, MALDI mass, and ESI mass experiments. The antimicrobial activity of $\varepsilon$-(L-$\beta$-Iysine) polypeptide is not only better than equal to the activity of known aminoglycoside type of antibiotics(MIC=3.125 - 6.25ug/mL) but also effective against aminoglycoside-resistant bacteria and fungi. If the mechanism of antimicrobial activity against aminoglycoside- resistant bacteria is figured out, the $\varepsilon$-(L-$\beta$-Iysine) polypeptide can be utilized for the treatment of diseases caused by aminoglycoside-resistant bacteria.

• Journal of Marine Bioscience and Biotechnology
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• v.14 no.2
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• pp.143-154
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• 2022

We isolated marine actinomycetes, strain D-5 which produces anti-methicillin resistant Staphylococcus aureus (anti-MRSA) compound. Streptomyces sp. D-5 relatively grew well in the 20~25℃, pH 8.0, and NaCl 3.0%. The ethyl acetate extract of D-5 culture was separated by C₁₈ ODS open column and reverse phase HPLC to yield anti-MRSA compound. The molecular weight of this compound was determined to be 898 by a Liquid chromatograph-mass spectrometer (LC-MS). Compared with penicillin G, this compound showed significant anti-MRSA activity. It also exhibited an inhibition zone of 26 mm at a concentration of 64 ㎍/disk and an inhibition zone of 16 mm at a concentration of 16 ㎍/disk against the MRSA KCCM 40511. Furthermore, the co-treatment of HPLC peak 5 compound and vancomycin caused a more rapid decrease in MRSA cells than each compound alone. It showed 86.8% growth inhibition activity within 12 hours at a low concentration of 50 ㎍/mL during co-treatment, and 97.1% growth in-hibition activity within 48 hours against MRSA KCCM 40511. Taken together, our results suggest that Streptomyces sp. D-5 and its anti-MRSA compound could be employed as a potent agent in MRSA infection.

• Microbiology and Biotechnology Letters
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• v.3 no.2
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• pp.63-68
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• 1975

A biological active substance was isolated from the cultured medium of Streptomyces sp. and its biochemical characteristics were investigated. Isolation process of the substance was as follows; the pH of filterate of the cultured medium was adjusted to 3.0 with N-hydrochloric acid and saturated with sodium chloride, then chloroform was added to this filterate in one fifth portions and stirred vigorously. After extracting the active substance with chloroform in 3 stages, the chloroform layer combined and evaporatea after dehydrating with sodium sulfate. The substance was found to be to be toxic to various fresh water fishes; the lethal dose for an average size Pseudorasbora parva T. et. S. was 50ug per ml. In the acidic condition, the toxicity of the substance remained fora long time, while in the alkaline state, the toxicity was decreased very fast. This substance was found to be stable to organic solvents, but labile to heat treatment. The maximal revival time of Pseudorasbora parva T. et. S. was about 20 minutes in 25 ug/ml of the substance solution.

• Journal of Microbiology and Biotechnology
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• v.30 no.7
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• pp.1082-1091
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• 2020

Microbial transglutaminases (MTGs) are widely used in the food industry. In this study, the MTG gene of Streptomyces sp. TYQ1024 was cloned and expressed in a food-grade bacterial strain, Bacillus subtilis SCK6. Extracellular activity of the MTG after codon and signal peptide (SP Ync M) optimization was 20 times that of the pre-optimized enzyme. After purification, the molecular weight of the MTG was 38 kDa and the specific activity was 63.75 U/mg. The optimal temperature and pH for the recombinant MTG activity were 50℃ and 8.0, respectively. MTG activity increased 1.42-fold in the presence of β-ME and 1.6-fold in the presence of DTT. Moreover, 18% sodium chloride still resulted in 83% enzyme activity, which showed good salt tolerance. Cross-linking gelatin with the MTG increased the strength of gelatin 1.67 times and increased the thermal denaturation temperature from 61.8 to 75.8℃. The MTG also significantly increased the strength and thermal stability of gelatin. These characteristics demonstrated the huge commercial potential of MTG, such as for applications in salted protein foods.

• The Plant Pathology Journal
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• v.15 no.1
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• pp.14-20
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• 1999

Twenty isolates of Helminthosporium species were obtained from various grass plants and tested for controlling efficacy on the development of plant diseases. An isolate of Helminthosporium sp. TP-4 was chosen and six antibiotic substances were purified from cultures of the fungus by repeated silica gel column chromatography and preparative thin-layer chromatography. They were identified as ophiobolin a, 6-epiophiobolin A, 3-anhydroophiobolin A, 3-anhydro-6-epiophiobolin A, iphiobolin B, and iphiobolin I mainly by mass spectrometry and nuclear magnetic resonance spectrometry. Ophiobolins inhibited the growth of a grampositive bacterium Streptomyces griseus, but were not active against gram-negative bacteria. They also showed an antifungal activity. In in vivo tests, iphiobolin B exhibited potent controlling activities against rice blast, tomato late blight, and wheat leaf rust with control values more than 90% and 70% at concentration of $500\mu\textrm{m}$/ml and 100 ${\mu}{\textrm}{m}$/ml. Ophiobolin A and 6-epiophiobolin A controlled the development of wheat leaf rust more than 80% at concentrations of 100 /ml and $500\mu\textrm{m}$/ml respectively. 3-Anhydro-6-epiophiobolin A was not active against any plant disease. On the other hand, the A-series ophiobolins other than 3-anhydroophiobolin A showed stronger phytotoxic activity in a leaf-wounding assay using 8 plant species than those of 3-anhydroophiobolin A, ophiobolin B, and ophiobolin I. The results indicate that there is little correlation between antifungal activity and phytotoxicity of ophiobolins.

• Microbiology and Biotechnology Letters
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• v.7 no.3
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• pp.135-140
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• 1979

A Streptomyces sp. strain AS-727 which was capable of producing penicillinase, was isolated from soil. The enzyme production was affected by the carbon and nitrogen sources added. Among them so far tested, glucose (or maltose) and sodium nitrate increased the enzyme production. And the amount of enzyme prodced reached maximum in 4 days cultivation. The optimla pH and temperature of the penicillinase was between pH 6.0 to 8.0 and 4$0^{\circ}C$ respectively. The stabel pH range of the enzyme was stable at 4$0^{\circ}C$, but it lost about 30％ and 40％ of the the activity respectively when it was treated at 6$0^{\circ}C$ and 8$0^{\circ}C$ for 60 minutes. The activity of the enzyme was inhibited by Z $n^{++}$, but A $g^{+}$, $Co^{++}$, $_Mn^{++}$, $Ca^{++}$, P $b^{++}$ did not affected enzyme activity. Peculiarly, the enzyme protein precipitated by freezing or addition of ammonium sulfate, urea, sodium chloride and some organic solvents as etanol, methanol, acetone was not dissolved in deionized water or any buffer solution.n.n.ion.n.n.