• Microbiology and Biotechnology Letters
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• v.20 no.6
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• pp.707-710
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• 1992

Bacillus stearothermophilus No.239 isolated from soil was mutated with N-methyl-N'nitro-N-nitrosoguanidine (MNNG) to yield a series of mutants with increasing levels of cyclomalto-dextrin glucanotransferase (EC 2.4.1.19` CGTase) production. After five consecutive mautation steps, a mutant MNNG 8 with about 14 times of CGTase activity than the parent strain was obtained.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1993.04a
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• pp.99-99
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• 1993

본 연구에서는 이미 benzo(a)pyrene유도 소핵시험에서 뚜렷하게 소핵생성억제능을 보인 polyhydroxy flavonol유도체중의 하나인 Galangin에 대하여 C57BL/6 mice를 이용하여 N-methyl-N'-nitro-N-nitrosoguanidine(이하 MNNG)에 의해 유도된 소핵생성빈도에 미치는 영향을 살펴보고, spleen lymphocyte 배양을 통해 bleomycin 및 MNNG유도 염색체이상에 미치는 영향과 MNNG에 의해 유발된 DNA adduts중 biomarker로서 7-methylguanine형성에 대한 Galangin의 영향을 살펴봄으로서 ,Galangin의 유전독성 억제효과 및 작용기전에 대한 연구를 하고자하며 향후 Galangin을 모핵으로하는 cancer chemopreventive agent로의 유도체 합성에 기여하고자 한다.

• Microbiology and Biotechnology Letters
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• v.21 no.6
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• pp.628-634
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• 1993

The inhibitory effects of various extracts from Chinese pepper on the mutagenicity and the growth of MG-63 human osteosarcoma cells were studied. Chinese pepper was extracted with methanol and then the methanol extract was further fractionated by using hexane, chloroform, ethyl acetate and butanol. The methanol extract of Chinese pepper revealed the strong antimutagenic activity on the aflatoxin B1(AFB1) and N-methyl-N'-nitro-N-nitrosoguanidine(MNNG) in Ames mutagenicity test and SOS chromotest.

• Proceedings of the Korea Environmental Mutagen Society Conference
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• 2001.10b
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• pp.98-98
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• 2001

• Proceedings of the Korean Society of Life Science Conference
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• 2002.03a
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• pp.52-52
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• 2002

• Korean Journal of Medicinal Crop Science
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• v.20 no.1
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• pp.16-19
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• 2012

The desmutagenic activity of the water extract of Areca catechu L. on the mutagenicity induced by aflatoxin $B_1$ ($AFB_1$), N-methyl-N-nitro-N'-nitrosoguani-dine (MNNG), mitomycin C (MMC) and 4-nitroquinoline 1-oxide (4-NQO) was studied by using the SOS Chromotest with Escherichia coli PQ37. The inhibition rates of water extract of Areca catechu L. at concentration of $100{\mu}g/assay$ were 41.0%, 47%, 46%, and 32% against $AFB_1$, MNNG, MMC and 4-NQO, respectively. The water extract of Areca catechu L. was separated into methanol soluble and methanol insoluble parts. The methanol insoluble part exhibited higher inhibition effect than the methanol soluble part against the mutagenic activities of MNNG. Step-wise fractionation of methanol insoluble part was done to obtain methanol, ethyl acetate and water fractions. Among these fractions, water fraction had the strongest inhibitory effect of 45.0% against mutagenicities of MNNG. The inhibition rates of aqueous fraction of methanol-insoluble from water extracted Areca catechu L. at concentrations of 1.61, 16.13, 161.29 and $322.58{\mu}g/mL$ were 12.0%, 24.0%, 47.5% and 62.0%, respectively. The water fraction showed the inhibitory effects with dose response against the mutagenic activity induced by MNNG.

• YAKHAK HOEJI
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• v.37 no.4
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• pp.350-355
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• 1993

The preparation of Streptococcus faecalis RSI is used as a medicinal preparation for human intestinal disorders. But the microbe in this preparation is very sensitive to rifampicin. If this preparation is taken with rifampicin, its therapeutic effect can not be expected. To develope rifampicin resistant mutants, the rifampicin sensitive strain S. faecalis RSI was treated with Nmethyl-N'-nitro-N-nitrosoguanidine(MNNG). Twelve strains of the MNNG-induced mutants showed distinct resistance to rifampicin and five mutants were selected for further studies. They also exhibited identical characteristics with the parent S. faecalis RSI when they were tested for lactic acid formation and growth inhibition of E. coli. From in vitro test, it was identified that rifampicin is not inactivated by certain factors of the rifampicin resistant mutants. Conclusively, the rifampicin resistant mutants are efficient strains that have insensitivity against rifampicin and original biochemical characteristics of the parent strain.

• Journal of Microbiology and Biotechnology
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• v.8 no.2
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• pp.119-123
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• 1998

The feasibility of using combined treatments of electric field and chemical mutagen N-methyl-N'-nitro-N-nitroso-guanidine (NTG) for the strain improvement of Saccharomyces sp. in ethanol production was examined. The treatment of electric field alone resulted in no effect on the lethality of yeast cells under the conditions of this study. However, when the electric field was applied together to the treatment of yeast cells with NTG, the electric field increased the lethal effect and auxotrophic mutation rate of NTG. The combined treatment of electric field and NTG also increased the chances of. obtaining superior yeast strains for the ethanol production from tapioca. A higher number of improved clones was obtained by the combined treatments of electric field and NTG than by the NTG treatment alone. The best clone, NF 30-9, which was also obtained by the combined treatment, produced $11.07\%$ (w/v) ethanol from tapioca slurry containing 25% (w/v) reducing sugar while the parental strain produced 9.77% (w/v).

• Microbiology and Biotechnology Letters
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• v.17 no.4
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• pp.327-333
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• 1989

The purplish-red pigment was formed on agar plate by superimposed streaking of Streptomyces propurpuratus ATCC 21630 and strain R-89, The strain No.89 was ascribable to the genus Bacillus and designated as Bacillus sp. R-89. Both strain did not produced such pigment when cultivated independently. For hyperpigment production, we selected the mutant S.P-6 from Streptomyces propurpuratus ATCC 21630 by MNNG (N-methyl-N'-nitro-N-nitrosoguanidine) treatment. Maximum purplish-red pigment 1420 mg/$m\ell$ were produced, when the mutant of R-16 and Bacillus sp. R-89 were mixed cultured at 3$0^{\circ}C$ for 72 hr.

• Korean Journal of Microbiology
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• v.24 no.2
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• pp.98-105
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• 1986

Rhizobium meliloti 102 F 51, the symbiotic partner of alfalfa, was mutagenized with N-methyl-N'-nitro-N-nitrosoguanidine (NTG) and UV-irradiation. Three group of mutants which form white, white-pink and red nodules were selected. The adetylene reduction activity, nodulation activity, amount of heme synthesis during the nodulation, and ${\delta}-aminolevulinic$ acid synthetase (ALAS) and ${\delta}-aminolevulinic$ acid dehydratase (ALAD) activities in free living rhizobia and bacteroid states of the each group of mutants were compared. The mutants forming white nodules showed lower acetylene reduction activity compared to those of red nodule forming mutants. The two key enzymes for the heme synthetic pathway, ALAS and ALAD activities of the mutants forming red nodules was much higher than those of the mutants forming white nodules in bacteroid state, however no significant difference was observed in free living state. In the nodules the ALAS was detected only in bacteroid fraction, while ALAD was detected both in bacteroid and plant fraction. ALAS was dramatically increased with the heme synthesis during the nodulation, while ALAD was decreased in plant fraction but slight increase was observed in bacteroid fraction.