• Microbiology and Biotechnology Letters
• /
• v.25 no.2
• /
• pp.144-150
• /
• 1997

After DNA damage, umuDC is the only SOS operon that must be induced to promote SOS mutagenesis in Escherichia coli. The recombinant plasmid pBC401 and pBC402 were constructed to fuse the lac structural genes with promoter region of umuDC operon to induce the expression of lacZ gene by DNA damage. We transformed the plasmid pBC401 and pBC402 into E. coli MC1061, lacZ deleted strain and determined the activity of $\beta$-galactosidase for various mutagen; UV, mitomycin C (MMC), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), 4-nitroqunoline-1-oxide (NQO), ethyl methanesulfonate (EMS). The $\beta$-galactosidase activities of PBC401 and pBC402 for UV, MMC, and NQO were increased in proportion to expression time until 3 hours thereafter, the activities were constant or slightly decreased. The activities for MNNG and EMS were not so high as for UV, MMC, and NQO. When MNNG and EMS were treated, $\beta$-galactosidase activity of pBC402 was slightly lower than pBC401 but when UV, MMC, and NQO were treated in pBC402, $\beta$-galactosidase activity was slightly higher than in pBC401. Therefore, the pBC402 was better than the pBC401 in terms of sensitivity for frameshift mutagen. We suggest that the plasmid pBC401 and pBC402 are easy to detect mutagens which cause frameshift mutation rather than point mutation.

• Journal of Microbiology and Biotechnology
• /
• v.6 no.2
• /
• pp.110-115
• /
• 1996

Yellow mutants of the astaxanthin producing red yeast Phaffia rhodozyma were obtained by nitrosoguanidine mutagenesis. The carotenoid composition of the yelow mutants, Yan-1 and Ny-1, was mainly $\beta$ -carotene (> 95$%$) and torulene (< 5$$). Therefore, the yellow mutants are carotene oxygenation deficient mutants (CODMs). CODMs produced decreased quantities of carotenoids compared to their red parents and this indicated that carotene may regulate its synthesis. CODMs, Yan-1 and Ny-4, on plates containing 50 $\mu$ M antimycin, showed highly pigmented vertical papillae. Antimycin-induced mutants purified from the papillae showed increases in carotenoid content (up to 1 mg $\beta$-carotene/g yeast). CODMs, Yan-1 and Ay-1, were more sensitive to antimycin than red strains, Ant-1 and 67-385. This was probably due to lower antioxidant activity of $\beta$-carotene than that of astaxanthin. Light increased torulene and light+antimycin further increased the torulene. Yan-1 and Ny-4 could grow with succinate, though their red parents, Ant-1 and Anf-1p, could not. However, antimycin induced mutation of Yan-1 or Ny-4 destroyed the ability to grow with succinate.

• Archives of Pharmacal Research
• /
• v.11 no.3
• /
• pp.218-224
• /
• 1988

The preparation of Clostridium butyricum is used as a normalizing agent for human intestinal flora. When the microbe is simultaneously used with rifampicin, it is inactivated by the antibiotic. To develop rifampicin-resistant mutants, rifampicin-sensitive strain Miyairi II 588 of C. butyricum was treated with nitrosoguanidine (NTG). To ensure stable resistance to rifampicin, we examined whether the resistance was plasmid-mediated or chromosome-mediated. It was found that the resistance of four mutant strains was not mediated by its inherent plasmid, but by the chromosomal mutation. These strains were examined for the susceptibility and resistance to other antituberculosis agents and antibiotics. The results showed that these mutants were resistant to the high concentration of the antituberculosis agents.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.23 no.6
• /
• pp.916-921
• /
• 1994

The inhibitory effects of the juice and boiling water extract of Houttuyina cordata Thunb., which has been known as a traditional folk antitumor agent, on the genotxicity induced by mutagens were investigated . For this purpose, Salmonella typhimurium TA98 and TA100, and the transheterozygous (mwh/+) third larvae of Drosophila melanogaster were used. The juice of fresh H. cordata 9JHC) and boiling H. cordata extract (BHC) showed antimutagenicities toared alfatoxin B₁ in S. typhimurium TA 98 and TA100. The JHC's inhibitory effect increased by 76% to 98% as the adding concentrations increased, and the BHC had a 86-97% inhibitory effect. however, in the case of N-methyl-N'-nitro-N nitrosoguanidine (MNNG), the JHC's inhibitory effect was 52-60% irrespectively of its concentrations and the BHC had a low inhibitory effect. The JHC and BHC slightly reduced the somatic chromosomal mutagenicity by MNNG in the wing hair spot test system (mwh/+) of D. melanogaster, which suggests that they can inhibit gene mutation , deletion and mitotic chromosomal recomgination.

• Microbiology and Biotechnology Letters
• /
• v.19 no.2
• /
• pp.122-127
• /
• 1991

A bacterial strain NO. 32 which produced thermostable ${\alpha}$-amylase was isolated from soil and identified to genus of Bacillus. To enhance ${\alpha}$-amylase productivity, a successive mutation of Bacillus sp. No. 32 was attempted with treatment of N-methyl-N'-nitro-N-nitrosoguanidine (NTG). The resulting mutant, Bacillus sp. No. 32H417, which is risistant to refampicin and deficient in spore formation, produced about 90-fold high level of ${\alpha}$-amylase when compared with parental strain. The properties of the enzyme for thermostability were investigated. The optimal temperature and pH for enzyme reaction were 95$^{\circ}C$ and pH6.5, respectively, in the presence of 0.3mM $Ca^{2+}$ as an effective stabilizer.

• Korean Journal of Microbiology
• /
• v.17 no.3
• /
• pp.137-151
• /
• 1979

Germinating conidia of Aspergillus nidulans diploid heterozygous for color and other genetic markers were used to direct and distinguish genetic events such as mutation, mitotic crossingover and nondisjunction in a single test after treatment with N-methyl-N'-nitro-N-nitrosoguanidine (NG), mitomycin C(MC), and chloral hydrate(CH). The following results were obtained : 1. NG reduced the survival of conidia and increased the frequencies of miototic segregants about sevenfoli over the control ; among the mitotic segregants the predominant genetic event was mitotic crossingover. NG also produced many abnormal colonies, which appeared to be of the types caused by induced semidominant lethals or chromosomal aberrations, and the aneuploid types found spontaneously. 2. After treatment with MC the survival of conidia was reduced but few abnormal colonies were produced. The frequencies of miotic segregants were increased about threefold over the control ; in the mitotic segeregants the induced genetic event was mitotic crossingover. 3. CH gave no apparent effect on the survival of conidia and the frequencies of mitotic segregants. However, CH generated abnormal colonies, very greatly, which turned out to be of the aneuploid types. This result suggests that CH interferes with the normal distribution of chromosomes in mitosis.

• KSBB Journal
• /
• v.14 no.3
• /
• pp.351-357
• /
• 1999

A marine bacterium Bacillus cereus ASK202, agarase producing strain, was treated with some mutagenic agents, ultraviolte(UV), 1-methyl-3-nitro-1-nitrosoguanidine(NTG), and ethyl methane sulfonate(EMS), several times for the increasing of the agarase production After mutagen treatment, we isolated one mutant strain treated with NTG showed the highest stability and agarase productivity and named as Bacillus cereus ASK202-N3. This Bacillus cereus ASK202-N3 strain was well grown in the modified marine medium containing 0.5%(w/v) agar, 0.3%(w/v) yeast extract, and 5.0%(w/v) NaCl, and the optimal initial pH, temperature and culture time were 7.8, $25^{\circ}C$ and 32h, respectively. In the optimal culture conditions, the agarase production was increased to 5.3 fold(850units/L) compared to that of the wild type.

• YAKHAK HOEJI
• /
• v.43 no.1
• /
• pp.124-127
• /
• 1999

Bifidobacterium infantis K-525 isolated from healthy Korean was susceptible to rifampicin and fluoroquinolones and resistant to other antituberculosis agents. When the preparation of this strain is taken as a therapeutics for human intestinal disorders with rifampicin or fluoroquinolones, its therapeutic effect can not be expected. So, B, infantis RFR-525 resistant to rifampicin was obtained by treating the parent B. infantis 525 with N-methyl-N'-nitro-N-nitrosoguanidine. B. infantis OFR-525 was produced by serial passage of B. infantis RFR-525 on agar with 2-fold minimal inhibitory concentration of ofloxacin. B. infantis OFR-525 was resistant to antituberculosis agents and fluoroquinolones up to 4∼128 fold higher than that for the original strain. The resistance of B. infantis OFR-525 against rifampicin and ofloxacin was maintained in vivo and in vitro. Conclusively, B. infantis OFR-525 can be regarded as a promising strain which can be developed as the preparation for the treatment of the intestinal disorders of the tuberculosis patients under rifampicin and ofloxacin therapy.

• Journal of Plant Biology
• /
• v.36 no.1
• /
• pp.105-112
• /
• 1993

Selection of glyphosate-resistant clones from MNNG-treated mesophyll protoplasts of haploid tobacco and their differentiation were studied. The protoplasts were treated with 0.1 to 100 $\mu\textrm{g}$/mL N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) for 30 min when they expanded to oval shapes. After the treatment, the protoplasts in 4-16 cell stages were transferred to the selective medium containing 1 mM glyphosate for the selection of the glyphosate-resistant colonies. The efficiency of the cell division of the protoplasts in the selective medium decreased as the MNNG concentrations in creased. Optimal MNNG concentration for induction of the glyphosate-resistant clones was 10$\mu\textrm{g}$/mL and mutation frequency was 2.66$\times$10-6. The stability of the glypohsate-resistance of the clones was examined by prolonged subculture in the medium with 1 mM glyphosate, and the resistant clones were survived more than 10 months. Among them one clone has been proliferating and greening and the others were proliferating without greening or greening with slower proliferating.

• The Journal of the Korean Society for Microbiology
• /
• v.22 no.2
• /
• pp.185-193
• /
• 1987

Ten species of herbae, which have been used to treat cancers in Chinese medicine, were tested to investigate their mutagenicity or antimutagenicity in S. typhimurium TA97, TA98, TA100, TA1535, and TA1538. Scolopendra centipede was weakly active in reversion of the frameshift mutation in S. typhimurium TA97 strain and the base-pair substitution in TA100 and TA1535 strains. Other herbae such as Coix lachryma, Dianthus superbus, Tricanthoshse kirilowii, Eupatorium formosanum, Lithospermum erythrorhizon, Ansaema japonicum, Curcuma zedoaria, Helicteres angustifolia, and Euonymus sieboldianus did not show any of the mutagenic potential, regardless of the metabolic activation with rat hepatic microsomal fraction. Dianthus superbus, Eupatorium formosanum, and Euonymus sieboldianus exhibited suppressive activities on microbial mutagenesis of N-methyl-N'-nitrosoguanidine, a base-pair substitution mutagen, in TA1535 and TA100 tester strains. The antimutagenic activities of Dianthus superbus and Euonymus sieboldianus appeared to be dose-dependant.