• Archives of Pharmacal Research
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• 제18권4호
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• pp.243-248
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• 1995

Seventeen transformation-deficient mutants of streptococcus pneumoniae, which are defective in competence induction (com), DNA uptake(ent) of recombination(rec), were investigated to determine sensitivity to ethylmethane sulfonate(EMS), methylmethane sulfonate(MMS), UV and mitomycin C. In ethylmethane sulfonate assay, the viability of most $com^-, \; rec^-\; and ent^-$ mutants was decreased about 2-10 times and the viability of ent-9 and ent-13 mutant was decreased about 33 and 25 times, respectively. On the other hand only half of the transformation-deficient mutants tested was sensitive to methylmethane sulfonate about 2 times and ent-12 mutant was sensitive to 2.0% MMS about 8 times. After UV and mitomycin C treatment, most of the mutants are not sensitive to UV and mitomycin C, although the viability of some transformation-deficient mutants was decreased slightly. Especially none of the com mutants were sensitive to DNA damage suggesting that competence is not involved in DNA repair. Also DNA uptake and recombination gane might be related to DNA repair function.

• International Journal of Industrial Entomology and Biomaterials
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• 제10권2호
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• pp.119-123
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• 2005

Benomyl-resistant mutants of entomopathogenic fungus, Metarhizium anisopliae were isolated and their physiological characteristics were investigated. These militants were obtained spontaneously or by UV irradiation in benomyl-treated media. Four spontaneous (S-2, S-11, S-18, S-19) and four UV-induced (UV-4, UV-5, UV-19, UV-24) mutants, which grow stably and normally were selected. No significant differences in conidia or hyphal shape, conidia viability, mycelial biomass, or virulent to the diamondback moth were observed between the wild type and their mutants. But differently from the mycelial growth of other benomyl-resistant mutants which was slower than that of the wild type on a modified Czapek-Dox, SDAY, $4\%$ chitin, or $1\%$ skim milk medium, that in the spontaneous mutants, S-18 and S-19, did not show any difference from the wild type. Especially, S-18 and S-19 grew well at benomyl concentrations up to 50 times or higher than that which inhibits wild type proliferation. These results suggested that S-18 and S-19 could potentially be used with the fungicide, benomyl.

• 미생물학회지
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• 제3권2호
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• pp.9-14
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• 1965

The enzyme-producing potentials of industrially important strains of Aspergillus spp. were studied. Irradiation of three original isolates of Aspergillus oryzae to ultra-violet rays resulted in the production of mutants which differed from the parent riboflavin and vitamin $B_{12}$ in culture media. 1. Irradition three strains of Aspergillus oryzae to ultraviolet light produced mutants and two strains of them were selected for soy sauce brewing. 2. The two strains are the physiological mutants of Aspergillus oryzae. Both were found to have superior enzyme activity to their relatives. 3. Aspergillus oryzae UV-induced mutant 172-722 and 569-713 were more powerful than others in the production of riboflavin and vitamin $B_{12}$. The enzyme activity of these strain were high and decreased only slightly even in 20 percent solution of NaCl. 4. Aspergillus oryzae UV-induced mutant 172-722 had more powerful protease producibility in wheat bran media than in modified Czapek's solution. On the contrary, Aspergillus oryzae UV-induced mutant 569-713 had more powerful producibility of saccharogenic and dextrinogenic amylase in modified Czapek's solution than in mold bran. 5. Aspergillus oryzae UV-induced mutant 172-722 formed the spore rapidly and Aspergillus oryzae UV-induced mutant 569-713 did ordinarily. 6. It is found from the results that Aspergillus oryzae UV-induced mutant 172-722 is valuable material for the manufacture of soy sauce because of its high protease activity in 20 percent solution of NaCl. Aspergillus oryzae UV-induced mutant 569-713 is suitable for soy bean mash and for fermented red pepper sauce for its high saccharogenic and dextrinogenic amylase activity in 20 percent solution of sodium chloride.

• 한국식품영양과학회지
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• 제33권6호
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• pp.1017-1021
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• 2004

Thr, Trp을 overproduce하는 효모 균주를 분리하기 위하여 Sacchromyces cerevisiae를 UV와 EMS로 mutagenesis한 후 screen하였다. Thr analogue인 hydroxynorvaline이 UV mutagenesis 후 Thr overproducing 하기 위해 사용되었다. 31 mutant 중 아미노산 분석 결과에 의해 TC 5-1이 선정되었고 다시 Trp overproducing 위해 EMS mutagenesis 하였다. 8개의 mutant가 flurotryptophan을 이용하여 Thr, Trp을 overproduce하는 mutant로 선정되었다. 아미노산결과에 의해 그 중 TC 6-1이 최종 효모 균주로 선정되었다.

• 공업화학
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• 제23권5호
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• pp.496-500
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• 2012

Arthrospira platensis (A. platensis)는 상업적으로 중요한 사상형 미세조류이다. 화학적 혹은 물리적 돌연변이원에 의해 유도된 변이주 분리는 균주 개량에 중요하게 작용한다. 본 연구에서, A. platensis에서 자외선(UV-B)조사에 따른 영향을 살펴보았고, 그에 따른 변이주를 확보하였다. A. platensis를 자외선(15 Watt, 254 nm)을 이용하여 1, 3, 5, 10 min 동안 처리 한 후, 얻어진 변이주를 각각 UM1, UM3, UM5, UM10으로 명명하였다. 특히, UM5 변이주는 야생균주와 비교하여 지질의 함량이 8~11배 가량 크게 증가하였다. 또한, 카로티노이드 함량과 항산화 효소(peroxidase, superoxide dismutase) 활성이 증가하였다. 이 결과, 자외선에 의해 유도된 변이주는 생리활성 물질을 축적하였으며, 이러한 유용성분을 생산하는 미세조류의 균주 개발은 미세조류의 산업화를 촉진시킬 것으로 기대된다.

• KSBB Journal
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• 제23권5호
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• pp.392-397
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• 2008

Recently, importance of immunosuppression is increasing as internal organ transplant becomes more prevalent with development of medical technology. Mycophenolic acid (MPA) is a selective inhibitor of guanine synthesis and it therefore has antibacterial, antiviral, antitumor and selective immunosuppressive activities. The objective of this study was to maximize MPA productivity through utilizing the MPA generating strain of Penicillium brevicompactum ATCC 16024, by inducing UV mutation and NTG mutation. The highest MPA obtained was 1.146 g/L, 2.051 g/L, and 1.390 g/L from P. brevicompactum UB-3, UB-9, UC-4 respectively mutants derived from UV treatment. P. brevicompactum NC-3 and NA-9 induced from NTG treatment yielded. 575 g/L, 2.238 g/L of MPA production respectively. Mutants capable of the highest observed production of MPA were P. brevicompactum UB-9 and P. brevicompactum NC-3 obtained using the UV and NTG treatments respectively.

• Journal of Microbiology
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• 제44권1호
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• pp.113-120
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• 2006

Candida tropicalis was treated with ultraviolet (UV) rays, and the mutants obtained were screened for xylitol production. One of the mutants, the UV1 produced 0.81g of xylitol per gram of xylose. This was further mutated with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), and the mutants obtained were screened for xylitol production. One of the mutants (CT-OMV5) produced 0.85g/g of xylitol from xylose. Xylitol production improved to 0.87 g/g of xylose with this strain when the production medium was supplemented with urea. The CT-OMV5 mutant strain differs by 12 tests when compared to the wild-type Candida tropicalis strain. The XR activity was higher in mutant CT-OMV5. The distinct difference between the mutant and wild-type strain is the presence of numerous chlamvdospores in the mutant. In this investigation, we have demonstrated that mutagenesis was successful in generating a superior xylitol-producing strain, CT-OMV5, and uncovered distinctive biochemical and physiological characteristics of the wild-type and mutant strain, CT-OMV5.

• Mycobiology
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• 제30권3호
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• pp.160-165
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• 2002

Aspergillus niger has been used as a host to express many heterologous proteins. It has been known that the presence of an- abundant protease is a limiting factor to express a heterologous protein. The protease deficient mutant of A. niger was obtained using UV-irradiation. A total of $1{\times}10^5$ spores were irradiated with $10{\sim}20%$ survival dose of UV, 600 $J/m^2$ at 280 nm, and the resulting spores were screened on the casein-gelatin plates. Ten putative protease deficient mutants showing the reduced halo area around colonies were further analyzed to differentiate the protease deficient mutant from other mutant types. Among ten putative mutants, seven mutants showed significant growth defect on nutrient rich medium and two mutants appeared to be the secretory mutants, which resulted in the impaired secretion of extracellular proteins including proteases. A mutant $pro^--20$ showed reduced halo zone without any notable changes in growth rate. In addition, the starchdegrading and glucose oxidase activities in the culture filtrate of $pro^--20$ mutant showed the similar range as that of the parental strain, which suggested that the $pro^--20$ mutant ought to be the protease deficient mutant rather than a secretory mutant. The reduced proteolytic activity of the $pro^--20$ was demonstrated using SDS-fibrin zymography gel. The reduced extracellular proteolysis was quantified by casein degradation assay and, comparing with the parental strain, less than 30% residual extracellular protease activity was detected in the culture filtrate of the $pro^--20$ mutant. The bio-activity of an exogenously supplemented hGM-CSF(human Granulocyte-Macrophage Colony Stimulating Factor) in the culture filtrate of $pro^--20$ mutant was detected until eight times more diluted preparations than that of the parental strain.

• Journal of Plant Biology
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• 제22권3호
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• pp.85-91
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• 1979

Tolerance against mercuric chloride in mutants of Pyricularia oryzae Cavara induced by ultraviolet(UV) irradiation has been investigated. The tolerant isolates obtained using ultraviolet(UV) irradiation were maintained a high level of tolerance even after 15 times transfer to the chemical free media. Each isolate of mutants UM-1, UM-2, and UM-3 on the successive monoconidial culture has genetically homogeneous for tolerance. The tolerant isolates sporulated less and showed a higher percentage of germination of conidia on media without the chemical than the parental isolate. The xotins released from the parental and the tolerant isolates have been identified as piricularin and $\alpha$-picolinic acid by paper-chromatography. The tolerant isolates produced more piricularin and its virulence on seedlings of rice varieties were higher than the parental isolates. Both piricularin production and virulance on rice were highest in the UM-2 isolate.

• Journal of Microbiology and Biotechnology
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• 제11권4호
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• pp.552-557
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• 2001

By UV-irradiation of Eremothecium ashbyii DTl, a higWy flavinogenic mutant (UV-18-57) and a nonflavinogenic mutant (UV -85) were obtained. The physio-morphological characteristics of these three strains were studied on glucose medium in submerged fermentation. Glucose utilization and mycelial growth occurred in 0 - 2 days of fermentation. By the third day, the biomass had declined. Extracellular riboflavin excretion was distinct from the second day, reaching a maximum rate by the fourth day. The hyphae of the highly flavinogenic mutant UV-18-57 were broader than DTl, while the nonflavinogenic UV-85 hyphae were very thin. Riboflavin accumulation was high in UV-18-57 (extracellular riboflavin,$825\mu\textrm{g}/ml$ , and intracellular, $490\mu\textrm{g}/ml$) and caused the mycelia to swell into bulbous forms. Riboflavin accumulation was less in DTl ($108\mu\textrm{g}/ml$ extracellular and $24\mu\textrm{g}/ml$ intracellular) and correspondingly its hyphae were thinner than those of UV-18-57 and swollen bulbous mycelia were not prominent. UV-85 was nonflavinogenic and, accordingly, its mOlphological characteristics included long thin filaments with no intracellular riboflavin accumulation. A large number of greenish fluorescence spores were seen in UV-18-57, whereas DTI had less spores and UV-85 was nonsporulating. Sporulation is correlated with riboflavin production. UV-18-57 had better mycelial integrity and lysis started only by the seventh day, whereas DTI and UV -85 started to lyze earlier by 4 -5 days. By the late stage of fermentation (eighth day), DTl had a few long, thin filaments indicating some secondary growth, whereas UV -85 showed a compact pellet form of mycelia. Most mycelia of UV-18-57 still appeared intact.