• 한국식품영양학회지
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• 제9권1호
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• pp.21-28
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• 1996

This study was attempted to investigate the production of L-tyrosine by Brevibacterium flavum ATCC 14067. To select the strain which produce more L-tyrosine, mutants were induced by N-methyl-N'-nitro-nitrosoguanidine (NTG) treatment and phenylalanine auxotrophic mutants were induced by NTG and penicillin treatments. PFP resistant mutant was isolated from a phenylalanine auxotroph by retreatment with NTG and screened for increase of L-tyrosine production. PFP-326 mutant resistant to PPP (100ug/ml) was derived from phenylalanine auxotroph by mutagenesis with NTG and PFP-106 mutant resistant to PFP (1201g/ml) was derived from PFP-326 by mutagenesis with NTG. The composition of media for L-tyrosine production in strain PFP-106 was studied. PFP-106 mutant strain produced 50mg 11 of L-tyrosine while the parent strain produced 0.56mg 11 of L-tyrosine. The optimum composition of medium for L-tyrosine by strain PFP-106 was 10cA sucrose as carbon source, 3% ammonium sulfate as nitrogen source. The optimum cultural condition for producing L-tyrosine by strain PFP-106 was L-phenylalanine at a concentration of 1000g/mg.

• 미생물학회지
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• 제24권2호
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• pp.98-105
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• 1986

Rhizobium melitoli 102F51에 N-methyl-N'-nitro-N-nitrosoguanidine 및 UV를 처리하여 heme 합성 특성이 다른 세 그룹의 mutant 즉 백색, 적백색 및 적색근류형성 mutant를 선별하여 이들 중 mutant들의 acetylene 환원력, 및 ${\delta}-aminolevulinic$ acid dehydratase (ALAD)를 free living 및 bacteriod 상태하에서 서로 비교하였다. 백색 근류를 형성하는 mutant는 적색 근류형성 mutant에 비하여 acetylene 환원력이 훨씬 낮았으며 ALAS 및 ALAD 활성은 free-living 상태에서는 각 mutant group 사이에서 큰 차이를 보이지 않았으나 bacteriod 상태에서는 백색근류생성 mutant에서 적색 근류형성 mutant group에 비하여 ALAS 및 ALAD 공히 현저히 낮았다. 근류에서 ALAS 활성은 heme 합성양에 비례하여 급진적으로 증가하였으나 ALAD 활성은 plant fraction에서는 감소하는 반면 bacteroid fraction에서는 완만하게 증가하였다.

• 한국미생물·생명공학회지
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• 제10권3호
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• pp.217-222
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• 1982

발효유 starter로서 사용하고 있는 유산간균 L. casei YIT 9018을 NTG로 처리하여 4종류의 phage(J$_1$, Tk93, PD5, $K_1$)에 대하여 저항성을 나타내는 8 개의 돌연변이균주(PR5, PR6, PR35, PR38, PR46, PR47, PR48)를 분리하여, 산생성력, 생육, 당발효성, 내균성을 시험하였다. Phage저항균주 8개중에서 특히 PR38은 4 종류의 phage에 대하여 4 개월동안 저항성을 유지하였고, 생육속도, 산생성력 등에 있어서 parent strain과 비교할때, 유의적인 차이가 없었고 (P>0.01), 인공위액에서의 내균성은 parent strain보다 약한 것으로 나타났다. 당발효성에 있어서는 양자 사이에 차이가 없었다. 본 실험에서 분리한 PR38은 발효유제조시에 phage가 감염되면, Parent strain 대용으로 사용할 수 있는 가능성이 제시되었다.

• 한국미생물·생명공학회지
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• 제47권4호
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• pp.581-584
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• 2019

In this study, the carbon monoxide (CO)-fermenting acetogen, Clostridium sp. AWRP was subjected to chemical mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine (NTG) to generate a CO-resistant mutant. Among the 26 colonies obtained, the highest alcohol production was observed in one isolate, named C1. Compared to the wild-type strain, the C1 strain exhibited 1.5- and 3.4-fold higher CO consumption rate and alcohol selectivity, respectively. The total CO consumption of strain C1 could be further enhanced by increasing the content of metal ions, such as nickel and iron. The highest ethanol titer (5.7 g/l) was achieved by 5-fold increase in the iron concentration.

• Journal of Microbiology and Biotechnology
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• 제2권2호
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• pp.102-107
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• 1992

For the purpose of producing L-ornithine by microbial fermentation, mutant strains were developed from glutamate-producing bacteria by mutagenesis using N-methyl-N'-nitro-N-nitrosoguanidine (NTG) and UV irradiation. Brevibacterium ketoglutamicum BK1046, a L-citrulline auxotroph which is also resistant to arginine hydroxamate (Arghx), was isolated and selected as the best producer of L-ornithine. This strain was capable of producing L-ornithine at a concentration of 24 g/l after 69 hours of cultivation in the 21 jar fermentor. The optimum supplementary level of L-arginine, a substitute for L-citrulline, was found to be about 0.2 g/l in the shake-flask fermentation.

• 미생물학회지
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• 제20권4호
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• pp.173-182
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• 1982

From FGSC 159 strain of Aspergillus nidulans, temperature sensitive mutants that are defective in growth and differentiation have been isolated by N-methyl-N'-nitroN-nitrosoguanidine (NTG) treatment. The optimum concentration of NTG and incubation time to get the highest mutation frequency was $100{\mu}g$ per ml and 1 hour, respectively. The survival frequency was 1%. Among the isolated mutants, five strains that were affected in early steps of differentiation were selected for further studies and named smK, smY, smB, smF, and smZ. The execution point of each mutant was determined and the growing pattern of each mutant at the restrictive temperature was observed under the microscope. Growth of mutant was arrested near at the execution point. From genetic analysis, each temperature-sensitive mutants was thought to have a single recessive gene. The genes of smK, smY, smB, smF, and smZ are linked to the chromosome VII, IV, VIII, I, and VI, respectively. It can be concluded that the genes controlling the differentiation are widely dispersed in the genome. From the results of mutant, smK, it is considered that a single gene can affect a function (functions) which act(s) at two different steps during differentiation.

• 한국미생물·생명공학회지
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• 제9권3호
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• pp.139-143
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• 1981

사과 식초 제조 과정 중 유기산의 변화를 검토하기 위하여 사과즙을 알콜발효시킨 후 Acetobacter aceti와 이 균에 NTG와 UV의 처리로 하여 얻은 변이주를 접종하여 식초산 발효를 시켰을 때 제조과정별로 유기산의 조성과 함량을 gas chromatography로 분석하여 다음의 결과를 얻었다. 1. 사과 원료 중 유기산의 함량은 malic acid 0.73 %, citric acid 0.038%, acetic acid 0.067%이었다. 2. 사과즙을 알콜발효시켰을 때 유기산의 함량은 malic acid 0.114%, lactic acid 0.1%, acetic acid 0.08%이었다. 3. 모균주와 변이주를 이용하여 얻어진 발효식초의 유기산 조성에 있어서는 차이가 없었고 함량에서는 차이가 있었다. 4. 변이주의 초기산 생성능은 모균주에 비하여 약간 빨랐다.

• 한국식품영양과학회지
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• 제29권6호
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• pp.987-994
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• 2000

한국 전통누룩으로부터 분리.동정된 Asp. coreanus NR 15-1, Asp. oryzae NR 15-3, 그리고 Asp. oryzae NR 2-5로부터 amylase활성이 높고 세포융합에 사용될 변이주를 분리하고 그의 특성을 검토했다. Aspergillus 속 사상균을 변이처리하기 위한 변이원으로는 NTG를 사용하였으며 Asp. coreanus NR 15-1로부터 총 15종의 변이주중 8종의 영양요구변이주, Asp. oryzae NR 15-3 으로부터 총 5종중 3종의 영양요구변이주를, Asp. oryzae NR 2-5로부터 총 6종중 2종의 영양요구변이주를 분리하였다. 이들 영양요구변이주는 최소배지 에서는 생육하지 않았으며 특정 아미노산과 핵산염기 등을 배지에 첨가했을 경우에만 생육하였다. 분리된 변이주의 당화력, 액화력 및 산 생성능 등을 검토한 결과, 산 생성능이 우수한 균주인 Asp. coreanus NR 15-1로부터 glucoamylase 활성이 높은 \ulcorner(Arg.￣) 변이주와 Asp. oryzae NR 2-5로 부터 $\alpha$-amylase 활성이 우수한 영양요구변이주인 Z6(Ade.￣) 변이주를 세포융합에 사용이 가능한 변이주라 사료되었다. 앞으로 이 들의 변이주를 대상으로 세포융합을 통해 우수한 사상균주를 획득할 수 있는 기초적 자료가 됨으로서 전통누룩의 과학화에 기여할 뿔만 아니라 외국 주류와 경쟁력이 있고 과학화된 전통주류의 개발이 가능하리 라 사료된다.

• 한국미생물·생명공학회지
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• 제23권1호
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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.

• 약학회지
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• 제38권5호
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• pp.595-601
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• 1994

Acetaminophen, a widely used analgesic, can be formed by N-acetylation and p-hydroxylation of aniline. Interspecific protoplast fusion technique was used to get acetaminophen directly from aniline and to increase the productivity of acetaminophen. Three auxotrophic mutants were obtained from S. griseus(ATCC 13273) and S. hygroscopicus(KCTC 1089) by N-methyl-N'-nitro-N-nitrosoguanidine(NTG) treatment. Regeneration frequencies of S. griseus$(his^-)$, S. griseus$(lys^-)$, S. hygroscopicus$(arg^-)$ were 42%, 45%, and 31%, respectively. Fusion of protoplasts carrying different auxotrophic markers was achieved by treatment with polyethylene glycol. When protoplasts were treated with 50% polyethylene glycol for 3 minutes, the fusion frequency between S. griseus$(his^-)$ and S. hygroscopicus$(arg^-)$ was $3.8{\times}10^{-5}$. The fusion frequency between S. griseus$(lys^-)$ and S. hygroscopicus$(arg^-)$ was $5.6{\times}10^{-4}$. When we checked the production of acetaminophen, thirty-four out of the fifty-six fusants produced larger amounts of acetaminophen than the parent strains did. Nine fusants produced twice more and twenty-five fusants produced one to two times more of acetaminophen than their parents.