• 미생물학회지
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• 제20권3호
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• pp.125-133
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• 1982

Mutational experiments were performed to imporve the cellulase productivity of Aspergillus phoenicis KU175, isolated from the southern part of Korea, as a high cellulase producer. By treatment ultra-violet light nad 4-NQO(4-Nitroquinoline-N-Oxide), mutation waas induced, and treatment ultra-violet light and 4-NQO (4-Nitroquinoline-N-Oxide), mutation was induced, and A.phoenicis KU175-115 was finally selected for its highest avicelase production. Avicelase production of the mutant was increased about 2 times compared with those of the wild strain. However, activities of other hydrolytic enzymes, such as amylase, protease and nuclease, of the mutant strain didn't show a marked difference compared with those of the nuclease, of the mutant strain didn't show a marked difference compared with the wild strain, except slight increase in ribonuclease activity and slight decrease in glucoamylase activity. Avicelases from the mutant strain selected were purified from wheat bran culture by successive salting out, followed by dialysis and column chromatography, and their charcteristics were compared with thosw of the wild strain. Avicelase was separated into three peaks in the mutant strain as well as in the case of wild strain. Avicelase II activity of the mutant strain was prominently higher than that of the wild strain, while avicelase I and III activities of those were equivalent. The optimal pH ranges and stability of avicelase II from the mutant strain were pH4-5 and pH3.5-6.0, respectively, as well as in the case of the wild strain. The optimal temperature and thermal stability of avicelase II from the mutant strain were $40{\sim}50^{\circ}C\;and\;20{\sim}55^{\circ}C$, respectively. These results were same as those of the wild strain. By the using of Eadie-Hofastee plot, $K_m\;and\;V_{max}$ of avicelase II from the mutant and the wild strain were calculated to be 2.29mg/ml and $4.84{\mu}g$ reducing sugar as glucose per min equally, from the line fitted to the data by the least square method. Activity of avicelase II from the mutant strain was slightly activated by $Mg^{++}\;but\;inhibited\;by\;Cu^{++}, \;Mn^{++}\;and\;Zn^{++}$, as well as in the case of the wild strain. Therefore, it was concluded that the mutant didn't induce the formation of another avicelase isozyme, or the changes in the properties of avicelase, but induce the changes in the productively of the same avicelase II by the action of regulatory gane.

• 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.

• Journal of Microbiology and Biotechnology
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• 제25권2호
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• pp.206-216
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• 2015

To clarify the role of surface protective antigen A (SpaA) in the pathogenesis of Erysipelothrix rhusiopathiae C43065 (serotype 2), the spaA deletion mutant of E. rhusiopathiae ${\Delta}spaA$ was constructed by homologous recombination. The virulence of the ${\Delta}spaA$ mutant decreased more than 76-fold compared with that of the wild-type strain C43065 in mice. The mutant strain was sensitive to the bactericidal action of swine serum, whereas the wild-type strain was resistant. The adhesion of wild-type strain to MEF cells was inhibited significantly by treatment with rabbit antiserum against recombinant SpaA (rSpaA) as compared with the treatment with normal rabbit serum, but the mutant strain was not affected. The mutant strain was readily taken up by mouse peritoneal macrophages in the normal rabbit serum, whereas the wild-type strain was resistant. Whereas the rabbit antiserum against rSpaA promoted the phagocytosis of wild-type strain by macrophages, the mutant strain was not affected. In addition, mice vaccinated with the formalin-killed mutant strain were provided 40% protection against challenge by the homologous virulent strain as compared with those with wild-type strain, NaOH-extracted antigen, or rSpaA, which provided more than 80% protection against the same infection. These suggested that SpaA has an important role in the pathogenesis of E. rhusiopathiae infection and could be a target for vaccination against swine erysipelas.

• 미생물학회지
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• 제18권4호
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• pp.161-171
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• 1980

A mutant strain having increased productivity of both enzymes, protease and amylase, was obtained from A. flavus KU 153, isolatd from South Korea for its high protease production by successive ultra-violet light irradiation, Two glucoamylases from the mutant strain selected were purified from wheat branculture by successive salting out, followed by dialysis and column chromatography, and their characteristics were compared with those of the wild strain. Glucoamylase production of the mutant selected was increased about 3.3 times compared with the wild strain, and 2.1 times compared with the parental strain, ${\alpha}-amylase$ activity of the mutant selected was about 2 times hugher than that of the wild strain or the parental strain. Protease and cellulase productivities of the muant selected were all alike compared with those of the highly proteolytic mutant, the parental strain. Therefore, it was considered that the back mutation on the protease production did not occurred in the formation process of the glucoamylase producing mutant. Total activities of glucoamylase I and II from the mutant selected were 2.86 and 3.65 times higher compared with those from the wild strain, respectively. Considering the optimal pH-thermal stability and Km-Vmax value of glucoamylase I and II from both strains, wild and mutant, it was deduced that the characteristics of glucoamylase I and II from the wild strain did not altered during the mutation process. Therefore, it was concluded that the selected mutant did not induce the formation of another glucoamylase isozyme, or the changes in the characteristics of the glucoamylase, but induce the productivity of the same glucoamylase I and II by the action of regulatory gene.

• The Plant Pathology Journal
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• 제16권4호
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• pp.200-205
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• 2000

Biological control of blue stain fungi, such as Ophiostoma and Leptographium spp., that reduce the quality of logs and cause economic losses in wood product industry, was carried out in laboratory and field trials by a colorless strain of Ophiostoma quercus, BSFcs-1. Inoculation of pine wood chips with the colorless strain 1 wk before inoculating wild-type strain demonstrated that BSFcs-1 colonized wood chips and excluded blue stain fungi from being established. Efficacy of BSFcs-1 was compared with colorless strain of O. piliferum, which is commercially available under the trade name of Cartapip. Inoculation of pine wood logs with the colorless strain 1 wk before inoculating wild-type strain of blue stain in isolated wood chips, while O. quercus and O. floccosum colonized 0% and 17%, respectively. Simultaneous inoculation of logs with the colorless and wild-type strains resulted in decreased colonization (28%) by BSFcs-1, but increased colonization by O. quercus (185) and O. floccosum (29%). On the other hand, BSFcs-1 and wild-type strain alone colonized 75% and 71%, respectively. Treatment of the surface of log ends with mycelial suspension of BSFcs-1 after cutting also showed good control of blue stain fungi in a pine forest stands.

• Journal of Microbiology and Biotechnology
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• 제9권6호
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• pp.789-793
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• 1999

The effect of acetic acid formation deficiency on recombinant E. coli fermentation was investigated using a mutant strain deficient in acetic acid formation. A mutant strain which does not grow under anaerobic conditions was isolated. The acetic acid production in this strain was negligible in aerobic batch fermentation. The cloned-gene expression in the mutant strain was higher than the wild-type strain. Fed-batch fermentations with controlled specific growth rates were carried out in order to compare the cloned-gene expression between the wild-type and the mutant strains. The expression decreased along with the specific growth rate in both strains. The cloned-gene expression in the mutant strain was 60% higher than in the wild-type strain at the same specific growth rate.

• 식물병연구
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• 제30권2호
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• pp.148-156
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• 2024

Ralstonia pseudosolanacearum은 토양과 물에서 오랫동안 생존하고, 가지과 작물에 심각한 풋마름병을 일으키는 식물병원세균이다. Simga S는 세균의 스트레스 환경에서 반응 또는 정지기 동안 유전자 발현을 조절하는 RNA 중합효소 복합체의 일부인 단백질이다. 본 연구는 스트레스 조건에서 R.pseudosolanacearum의 sigma S의 역할을 조사하기 위해서, R.pseudosolanacearum의 GMI1000 균주의 sigma S를 암호화하는 rpoS 유전자 변이체를 준비하여 야생형 균주와 세균의 특징을 비교하였다. 아울러 rpoS 유전자 역할은 원래 유전자를 변이체에 도입하여 rpoS 유전자 표현형 회복을 확인하였다. 야생형 균주와 rpoS 결여 변이체는 생장 속도, 외피다당류 생산, 식물체에서 병원성, 식물 세포벽 분해 효소 활성에서 차이를 보이지 않았다. 그러나 야생형 균주는 영양분결핍 조건에서 변이체보다 더 민감하게 반응하였고 과산화수소가 첨가된 조건에서 변이체보다 덜 민감하게 반응하였다. 흥미롭게도 영양분결핍 조건에서 rpoS 결여 변이체에서는 장기간 생균수를 유지하지만, 같은 조건에서 야생형 균주 생균수는 빠르게 감소하였다. 그리고 두 균주 배양액 pH를 측정한 결과, 야생형 균주와 변이체 간에 상당한 차이가 나타났다. 야생형 균주는 생장하면서 빠르게 배지의 pH가 감소하여 산성화되었다. 그러므로 야생형 균주의 빠른 사멸은 배지가 산성화되면서 정지기 상태 세균의 산성 pH에 대한 민감도 때문일 것이다. Biolog 분석으로 rpoS 변이체는 acetic acid, D-alanine, D-trehalose, L-histidine을 이용하지 못함을 확인하였다. 본 연구 결과는 R. pseudosolanacearum 세균의 sigma S가 영양분결핍 조건에서 정지기 동안 유기산 생산 또는 이용을 조절하며 정지기 세포사멸도 조절하는 것을 보여준다.

• 한국해양바이오학회지
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• 제1권2호
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• pp.84-90
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• 2006

Vibrio fluvialis의 opp gene cluster내에 존재하는 oppABCDF 유전자를 allelic exchange 방법에 의해서 각각의 유전자가 deletion된 mutant를 제조하였다. 각각의 유전자가 deletion된 mutant의 확인은 PCR과 Southern hybridization으로 결정하였다. 각 mutant들을 BHI 배지에서 생육을 비교한 결과 배양후 4시간 이전까지는 wild strain이 모든 mutant들에 비해서 생육이 좋았으나 4시간 이후부터는 같은 수준의 생육을 보여주었다. Biofilm 생산을 비교한 결과 ${\Delta}oppA$ mutant에서 가장 높은 생산성을 보여주었다. ${\Delta}oppC,D,F$ mutant들의 biofilm 생산은 ${\Delta}oppA$ mutant 보다는 낮았으나 wild strain보다는 높은 biofilm 생산성을 보여주었다.

• Journal of Microbiology and Biotechnology
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• 제3권2호
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• pp.95-98
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• 1993

This study was carried out to isolate and characterize the mutant strains of Schwanniomyces castellii NRRL Y-2477. Mutants were prepared with the treatment of ethyl methane sulfonate. 2-deoxy-D-glucose resistant mutants were isolated and two mutants were selected based on their high production of amylolytic enzymes and their ability to ferment starch. The mutants selected had higher a-amylase and glucoamylase activities than the wild type strain from several other carbon sources. Especially, it was revealed that mutant strain M-9, when cultured in the presence of glucose as a sole carbon source, shows relatively high activities of a-amylase and glucoamylase compared to those of the wild type strain. In result, this mutant strain can be considered as a constitutive producer of amylolytic enzymes. To compare the ethanol production ability of wild type strain and of mutant strains selected, an alcohol fermentation was carried out using 100 g/l soluble starch. Mutant strain M-9 did not improve the direct alcohol fermentation of starch, despite its excellent amylolytic activities performance. On the other hand, mutant strain M-6 produced 37.9 g/l (4.8%, v/v) ethanol by utilizing about 82% of substrate.

• Journal of Microbiology and Biotechnology
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• 제15권2호
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• pp.247-253
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• 2005

The bacterial cellulose (BC) production by a wild­strain Acetobacter xylinum BPR2001 and that by its acetan­nonproducing mutant, EPI, were compared in a jar fermentor. EPI produced about $28\%$ less BC than the wild-strain. The apparent difference in the cultivation of the two strains was the viscosity increase in the culture broth that was closely associated with acetan production. Increasing the viscosity of the culture broth of EPI by adding agar led to the formation of relatively small and uniform BC pellets, and BC production consequently became two-fold higher than that in the absence of agar and was almost equal to that by BPR2001. Therefore, acetan has an important role in BC production by inducing physical changes in the culture broth of the wild-type strain.