• Korean Journal of Microbiology
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• v.33 no.3
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• pp.199-202
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• 1997

The effect of electric shock (AC 38 Vll.3 cm) on the lethal effect and induction rate of mutation of chemical mutagen N-methyl-N'-nitro-N-nitrosoguanidine (NTG) was examined by using the spores of Streptomyces and the cells of haploid and polyploid yeast strains of Saccharomyccrs. Spores of Sireptomyces were all alive after 180 min of electric shock, hut all dead after 960 min-treatment. When the spores of Streptomyces or the cells of haploid and polyploid yeast were treated with electric shock and NTG, the electric shock increased the lethal effect of NTG; the survival rate of Streptomyces dropped from 72 to 48% after 180 min-treatment and those of haploidand polyploid-yeast decreased from 8 to 3% and 25 to lo%, respectively, after 40 min-treatment. The electric shock also increased mutation rates of Streptomyces and haploid yeast. from 1.8 to 13.6%' after 120 min-treatment and from 2.4 to 4.8% after 40 min-treatment, respectively.

• 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.

• Microbiology and Biotechnology Letters
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• v.27 no.5
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• pp.399-403
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• 1999

For the production of trehalose, microorganisms capable of producing trehalose extracellularly were screened from the stock cultures in our laboratory. among them, Micrococcus luteus IFO 12708 showed the highest productivity of trehalose. For the increase of productivity, the mutant strai Hs-208 having higher trehalose production was selected with NTG(N-methyl-N'-nitrosoguanidine) mutagenesis, which led to the decrease of the specific activity of trehalose phosphorylase(3.2-fold) as compared to the wild strain. The optimum condition for the trehalose production was established as follows: 20g/l of glucose and 6g/l of tryptone were used as a sole carbon source and nitrogen source, respectively, and cultivations were carried out at 3$0^{\circ}C$ and pH 6.0. After 20hrs cultivation, addition of 20unit/ml penicillin G led to the higher conversion yield of trehalose. Under the optimum condition, 6.547g/l trehalose was produced with conversion yield of 32.7%.

• Microbiology and Biotechnology Letters
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• v.19 no.6
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• pp.614-618
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• 1991

Antifungal compound, KRF-001, was produced by Bacillus subtilis subsp. krictiensis isolated from soil. Physico-chemical factors affecting cell growth and bioactivity were examined to improve the production yield. Nutrient composition, temperature, pH and phosphate ion concentration were proved to be important factors for the production of KRF-001. Mutation was performed to select high yielding strains. First, mutation was performed with ultra-violet light, and the second mutation process was conducted by MNNG (N-Methyl-N'-nitro-N-nitrosoguanidine) resulting in three high yielding strains.

• YAKHAK HOEJI
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• v.38 no.3
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• pp.332-337
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• 1994

Using germinal and somatic cell mutation assaying systems of Drosophila melanogaster, effects of Ginseng and Salvia miltiorrhiza extracts on the in vivo mutagenicity induced by N-methyl-N'-nitro-N-nitrosoguanidine(MNNG) were investigated. For these purpose, the attached-X method and the mwh/flr spot test system which are an X-linked lethal mutation and a somatic chromosome mutation assaying system, respectively, were used. In the induction of X-linked lethal mutations during the spermatogenesis, MNNG showed more actions in the sperm and spermatid stages, in which Ginseng and Salvia miltiorrhiza extracts had remarkable inhibitory effects than other stages. Ginseng and Salvia miltiorrhiza extracts reduced the mutagenicity by MNNG in the mwh/flr system, which reveal that they can inhibit gene mutation, deletion and mitotic chromosomal recombination. These results seem to suggest that Ginseng and Salvia miltiorrhiza extracts may exert their inhibitory effects to in vivo mutagenic and/or carcinogenic properties of DNA-damaging agents.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2001.11a
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• pp.168-170
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• 2001

생물 계면활성제의 개발을 위해 MNNG(N-Methyl-N-Nitro- Nitrosoguanidine), EMS, UV radiator random mutation을 통해 가장 우수한 biosurfactant 생산 균주를 선별하였는데 MNNG를 처리한 균주가 유화활성 1.950, 표면장력 29.0dyne/cm으로 공시균주인 Pseudomonas aeruginosa EL-MS 유화활성 0.456과 표면장력 33.0dyne/cm에 비해 우수하였다.

• The Korean Journal of Mycology
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• v.21 no.3
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• pp.230-234
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• 1993

In order to isolate mutants in Rhizopus nigricans, the optimal treatment conditions for the chemical mutagens, N-Methyl-N'-Nitro-N-Nitrosoguanidine(MNNG) and Ethyl Methane Sulphonate(EMS), were explored. When MNNG was used as the chemical mutagen, the optimum concentration and treatment time for the best mutation frequency were $125{\mu}g/ml$ and 60 minutes, respectively. Under the optimum conditions for MNNG, the survival rate was 0.1-1.0%. The leucine auxotroph could be isolated. The phenotypic characteristics of the three mutants prepared are as follows; shortened sporangiophore, spiral sporangiophore, and reduced size of sporangium and sporangiospore. However, EMS as the chemical mutagen was ineffective for this species.

• Mycobiology
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• v.39 no.1
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• pp.20-25
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• 2011

Spores of Aspergillus sp. SU14 were treated repeatedly and sequentially with $Co^{60}$ ${\gamma}$-rays, ultraviolet irradiation, and N-methyl-N'-nitro-N-nitrosoguanidine. One selected mutant strain, Aspergillus sp. SU14-M15, produced cellulase in a yield 2.2-fold exceeding that of the wild type. Optimal conditions for the production of cellulase by the mutant fungal strain using solid-state fermentation were examined. The medium consisted of wheat-bran supplemented with 1% (w/w) urea or $NH_4Cl$, 1% (w/w) rice starch, 2.5 mM $MgCl_2$, and 0.05% (v/w) Tween 80. Optimal moisture content and initial pH was 50% (v/w) and 3.5, respectively, and optimal aeration area was 3/100 (inoculated wheat bran/container). The medium was inoculated with 25% 48 hr seeding culture and fermented at $35^{\circ}C$ for 3 days. The resulting cellulase yield was 8.5-fold more than that of the wild type strain grown on the basal wheat bran medium.

• Microbiology and Biotechnology Letters
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• v.19 no.2
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• pp.140-146
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• 1991

Mutation experiments were performed to select the mutant of Aspergillus niger 55, which had lost almost all the ability to produce transglucosidases but retained that of high productivity of raw meal saccharifying enzyme, by means of successive induction with N-methyl-N'-nitro-N-nitrosoguanidine(MNNG), ultraviolet(UV) light, and ${\gamma}$-rays. Also, we used the mutant enrichment techniques, such as liquid culture-filtration procedure and differential heat sensitivity of conidia, in order to increase the possibility of obtaining a mutant. The glucoamylase productivity of mutant PFST-38 was 11 times higher than that of the parent strain. The mutant PFST-38 was morphologically identical to the parent strain, except for the size of conidia, the tendency to form conidia and the lenght of conidiophore. Asp. niger mutant PFST-38 apeared to be useful for the submerged production of the raw corn meal saccharifying enzyme.

• Microbiology and Biotechnology Letters
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• v.23 no.1
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• pp.47-52
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• 1995

Since the original productivity of new aminopeptidase M inhibitors MR-387A and B by Streptomyces sp. SL-387 (KCTC 0102BP) was not enough for further chemical and biological evaluation, mutation of parent strain by the treatment of N-methyl-N'-nitro-N-nitrosoguanidine was performed in order to obtain a clone with greater inhibitory activity. Mutant N-3 was selected due to a 6-fold greater productivity (40 $\mu$g/ml) than that of the wild type(6.7 $\mu$g/ml). This mutant was resistant to 3,4-dehydro-DL-proline, an antimetabolite of proline, with 25 $\mu$g/ml of minimum inhibitory concentration. Furthermore, the characteristic morphological change from spiral spore chain in wild type to straight in mutant was observed. An aminopeptidase M nhibitor different from MR-387A and B was isolated from the culture broth of the mutant. This inhibitor was composed of 2 proline, 1 valine, and an unknown amino acid which is presumably 3-amino-4-phenylbutanoic acid. IC$_{50}$ value (89.1 $\MU$g/ml) of the purified inhibitor was lower than that of other inhibitors, which may be due to the absence of 2(S)-hydroxyl group within the structure of 3-amino-4-phenyl- butanoic acid.