• Journal of Microbiology and Biotechnology
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• 제8권2호
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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).

• International Journal of Industrial Entomology and Biomaterials
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• 제2권2호
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• pp.185-189
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• 2001

Wild type Bacilus thuringiensis subsp. israelensis and B. sphaericus toxins have been used separately as active in ingredients for bacterial insecticides to control mosquito larvae due to their comparable toxicity to chemical insecticides. Cry11B, recently cloned from B. thuringiensis subsp. jegathesan, shows higher toxicity against three major species of mosquito larvae than Cry11A, one of the major component of B. thuringiensis subsp. israelensis inclusion body. To determine whether the combination of cry11B and B. sphaericus binary toxins is as toxic as B. thuringiensis subsp. israelensis parental strain, cry11B and B. sphaericus binary toxins genes were co-expressed as an operon using cytlA promoters/STAB-SD hybrid expression system in B. thuringiensis subsp. israelensis acrystalliferous strain 4Q7. However, unexpectedly, B. sphaericus binary toxins were barely produced, whereas relatively large amount of Cry11B was produced. When this strain was grown in four different media, NB+G and Peptonized Milk produced more toxin proteins and spores per unit of media than GYS and G-Tris. Toxicity of this strain against fourth instar Culex quinquefasciatus was ranged from of 8.3 to 45.7 ng/ml, with NB+G culture being the highest, and GYS culture was the lowest.

• 대한가정학회지
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• 제36권12호
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• pp.55-71
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• 1998

The purpose of this study was to identify the characteristics of coping behaviors of non-professional working mothers and find out the individual and situational factors which affect the degree of coping behaviors. For this research, the working mothers in non-professional job with children under age 18 answered the structured questionaire. The findings were as follows. First, the degree of coping behaviors was rather high in multiple role management strategies, strengthening family system and positive thinking, but rather low in housework socialization and role reduction/standard adjustment. Second, the effect of associated variables were different according to the subcategories of coping behaviors. So we conclude that, the coping behaviors of the non-professional working mothers were different from those of professional working mothers in some aspects, althought they have much similarities. The different aspects were 1) The relationship of family income and the degree of housework socialization was more evident. 2) The work-related variables did not affect the coping process significantly because of the conservative sex-role attitued of them. Second, non-professional working mothers should use coping behaviors such as housework socialization, role reduction/standard adjustment more for the more effective management of the role strain. Third, the attitude of occupational and parental role was one of the most important factors in using the role strain coping behaviors. And such an unconscious use of the coping behavior won't be helpful in the feeling of control over environment including role strain and active coping of working mothers.

• 미생물학회지
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• 제26권2호
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• pp.93-100
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• 1988

In order to understand the regulation of glutamate dehydrogenase(GDH) synthesis in Brevibacterium flavum, we have isolated a mutant lacking NADP-linked GDH activity by ethlmethane sulfonate treatment. The $gdh^-$ mutant was grown on the minimal plate with 1mM ammonium chloride and not that with 300mM ammonium chloride. The cell-free extracts from $gdh^-$ mutant and prototroph were also examined with glutamine synthetase(GS) and glutamate synthase (GOGAT) production by niteogen sources. The growth of $gdh^-$ mutant in presence of 20mM ammonium chloride means that GOGAT synthesis is sufficient to allow growth in this condition. GS production of $gdh^-$ mutant as well as parental strain was induced by 1mM urea and ammonium tartrate, but it was repressed by higher concentration of ammonia, and also induced by 20mM to 50mM glutamate as a substrate. It was special attention that GOGAT synthesis from $gdh^-$ strain was more repressed by higher concentration of ammonia than prototroph as described in E. coli system.

• 한국미생물·생명공학회지
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• 제19권2호
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• pp.122-127
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• 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.

• Advances in Traditional Medicine
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• 제2권1호
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• pp.64-67
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• 2002

In the course of screening for new anticancer antibiotics from myxobacteria, strain JW357 was found to produce an antibiotic that was active against several human cancer cell lines. This strain was identified as Angiacaccus disciformis by morphological and cultural characteristics. The antibiotic produced was identified as myxochelin A. It demonstrated significant cytotoxicity against certain human cancer cells with $IC_{50}$ values ranging 1.15 to $2.36{\mu}g/ml$. Myxochelin A was interestingly as active against multidrug-resistant CL02 cells as against the sensitive parental cells (HCT15).

• 약학회지
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• 제46권2호
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• pp.108-112
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• 2002

Drug resistance is one of the most significant impediments to successful chemotherapy of cancer. Multidrug-resistance (MDR) is characterized by decreased cellular sensitivity to anticancer agents due to the overexpression of P-glycoprotein. By employing a resistant subline of HCT15 to adriamycin (CL02), we undertook the screening for agents which were effective to multidrug-resistant cancer cells. As a result, a myxobacterial strain JW150 was selected for study since an activity against CL02 cells was discovered in the strain. Cytotoxicity-guided fractionation of the culture broth led to the isolation of cystothiazole A and melithiazole F. The producing organism was identified as Myxococcus stipitatus by taxonomic comparison with type strains of Myxococcus sp. as well as its morphological and physiological characteristics. Cystothiazole A and melithiazole F demonstrated potent cytotoxicity against certain human cancer cells with $IC_{50}$ values ranging from 0.03~ $0.72{\mu}{\textrm{g}}$/ml. Both compounds were interestingly as active against drug-resistant sublines CL02 and CP70 as against the corresponding parental cells.

• 한국미생물·생명공학회지
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• 제18권6호
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• pp.607-612
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• 1990

생분해성 고분자로서 중요한 poly-$\beta$-hydroxybutyrate(PHB)의 생합성에 있어서 포도당과 암모늄농도의 영향을 규명하기 위하여 Alcaligenes eutrophus를 회분식으로 배양하였다. PHB는 질소원이 고갈되면서 생성되었고 건조세포무게의 약 80까지 축적되었다. 초기 포도당농도가 높을수록 세포성장과 PHB 합성은 억제되었지만 최종 세포농도와 건조세포무게에 대한 PHB 축적비는 증가하였다. 초기 암모늄농도가 낮을수록 최종 세포와 PHB 농도가 낮았지만 건조세포무게에 대한 PHB 축적비는 증가하였다. 배양도중 산소공급을 중단했을 때 세포성장과 PHB 합성이 중단되었다.

• Journal of Microbiology and Biotechnology
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• 제25권10호
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• pp.1621-1628
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• 2015

Chlamydia possesses a conserved 7.5 kb plasmid that is known to play an important role in chlamydial pathogenesis, since some chlamydial organisms lacking the plasmid are attenuated. The chlamydial transformation system developed recently required the use of plasmid-free organisms. Thus, the generation and identification of plasmid-free organisms represent a key step in understanding chlamydial pathogenic mechanisms. A tricolor immunofluorescence assay for simultaneously detecting the plasmid-encoded Pgp3 and whole organisms plus DNA staining was used to screen C. muridarum organisms selected with novobiocin. PCR was used to detect the plasmid genes. Next-generation sequencing was then used to sequence the genomes of plasmid-free C. muridarum candidates and the parental C. muridarum Nigg strain. We generated five independent clones of plasmid-free C. muridarum organisms by using a combination of novobiocin treatment and screening plaque-purified clones with anti-Pgp3 antibody. The clones were confirmed to lack plasmid genes by PCR analysis. No GlgA protein or glycogen accumulation was detected in cells infected with the plasmid-free clones. More importantly, whole-genome sequencing characterization of the plasmid-free C. muridarum organism and the parental C. muridarum Nigg strain revealed no additional mutations other than loss of the plasmid in the plasmid-free C. muridarum organism. Thus, the Pgp3-based immunofluorescence assay has allowed us to identify authentic plasmid-free organisms that are useful for further investigating chlamydial pathogenic mechanisms.