• Journal of Microbiology and Biotechnology
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• 제28권12호
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• pp.2064-2070
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• 2018

Pseudomonas tolaasii 6264 is a representative strain that causes bacterial blotch disease on the cultivated oyster mushroom, Pleurotus ostreatus. Bacteriophages are able to sterilize the pathogenic P. tolaasii strains, and therefore, they can be applied in creating disease-free mushroom cultivation farms, through a method known as "phage therapy". For successful phage therapy, the characterization of phage-resistant strains is necessary, since they are frequently induced from the original pathogenic bacteria in the presence of phages. When 10 different phages were incubated with P. tolaasii 6264, their corresponding phage-resistant strains were obtained. In this study, changes in pathogenic, genetic, and biochemical characteristics as well as the acquired phage resistance of these strains were investigated. In the phylogenetic analyses, all phage-resistant strains were identical to the original parent strain based on the sequence comparison of 16S rRNA genes. When various phage-resistant strains were examined by three different methods, pitting test, white line test, and hemolytic activity, they were divided into three groups: strains showing all positive results in three tests, two positive in the first two tests, and all negative. Nevertheless, all phage-resistant strains showed that their pathogenic activities were reduced or completely lost.

• 한국가금학회지
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• 제28권2호
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• pp.83-89
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• 2001

열 안정성을 가지고 있는 한국산 꿩에서 분리된 New-castle disease virus CBP-1주는 9일령 SPF 계태아에 접종되어 $37^{\circ}C$에서 배양하는 방법으로 173번(parent주) 누대 배양되었다. $37^{\circ}C$에서 173번 누대 배양된 NDV CBP-1 주를 10 일령 계태아에 접종한 후 저온에서 ($29^{\circ}C$) 15번 (CA-15) 30번(CA-30) 누대 배양하였다. 저온순화 주인 CA-15주와 CA-30주의 이화학적 성상검사 (열 안정성 실험, 지질 용매에 대한 감수성 실험, 산성 용매에 대한 감수성 실험)와 병원성 실험(MDT, ICPI, IVPI), 온도 감수성 실험, 안전성 실험, 부스터 효과 실험, 방어효과 등을 실험하였고, $37^{\circ}C$에서 173번 누대 배양된 parent주와 비교하였다. $29^{\circ}C$에 적응된 CA-30주는 $37^{\circ}C$와 $41^{\circ}C$에서 세포 감염력이 parent주와 비교할 때 감소하였다. CA-15주와 CA-30주를 $56^{\circ}C$에서 30분, 60분, 120분 동안 처리하였을 때 이들 저온 순화주들은 혈구응집능과 세포감염력을 상실하였다. Parent주와 CA-15, CA-30주는 ethyl ether를 10분간 처리했을 때 혈구응집능과 세포 감염력을 모두 상실하였다. 그러나 parent주와 CA-15, CA-30주는 pH 3.0-glycine HCl 완충액에 60분간 처리하였을 때 혈구응집능을 가지고 있었다. Parent주의 대뇌병원성 지수와 정맥내 병원성 지수는 각각 1.12, 1.45 이었다. 그러나 CA-30주의 대뇌 병원성 지수와 정맥내 병원성 지수는 각각 0.75, 0.00으로 감소하였다. CA-30주의 안전성은 1 일령 병아리에서 실시하였고 parent주와 B-1주와 비교였다. 이들의 안전성은 치사율을 가지고 평가하였다. parent주와 CA-30주와 B-1주의 치사율은 각각 17.5, 12.0. 0.0%이었다. CA-30주가 parent주에 비해 보다 높은 안전성을 보여 주었으나 B-1주에 비해서 아직 높은 치사율을 보여 주고 있었다.

• Journal of Microbiology and Biotechnology
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• 제27권7호
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• pp.1223-1232
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• 2017

Cordyceps militaris, a member of Ascomycota, a mushroom referred to as caterpillar Dong-chung-ha-cho, is commercially valuable because of its high content of bioactive substances, including cordycepin, and its potential for artificial cultivation. Cordycepin (3'-deoxyadenosine) is highly associated with the pharmacological effects of C. militaris. C. militaris is heterothallic in that two mating-type loci, idiomorph MAT1-1 and MAT1-2, exist discretely in two different spores. In this study, nine C. militaris strains were mated with each other to prepare newly bred strains that produced a larger amount of cordycepin than the parent strains. Nine strains of C. militaris were identified by comparing the internal transcribed spacer sequence, and a total of 12 single spores were isolated from the nine strains of C. militaris. After the MAT idiomorph was confirmed by PCR, 36 mating combinations were performed with six single spores with MAT1-1 and the others with MAT1-2. Eight mating combinations were successfully mated, producing stroma with perithecia. Cordycepin content analysis of all strains by high-performance liquid chromatography revealed that the KASP4-bred strain produced the maximum cordycepin among all strains, regardless of the medium and stroma parts. Finally, universal rice primer-PCR was performed to demonstrate that the bred strains were genetically different from the parental strains and new C. militaris strains. These results may be related to the recombination of genes during mating. The newly produced strains can be used to meet the industrial demand for cordycepin. In addition, breeding through mating suggests the possibility of producing numerous cordycepin-producing C. militaris strains.

• KSBB Journal
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• 제14권6호
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• pp.682-687
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• 1999

Streptomyces virginiae 유래의 virginiamycin 생합성 유도인자인 VB-C를 이용하여 다른 방선균에의 항생물질 생산 유도 기능을 검토하였다. Erythromycin 생산균인 Streptomyces erythraeus를 공시균주로 사용하였으며, VB-C 결합 receptor 유전자가 포함된 plasmid(pARS 701, 9 kb)를 공시균주에 도입하여 transformant로 사용하였다. Parent와 transformant 모두 유도인자인 VB류를 생산하였으며, VB-C의 signal 전달에 관여하는 결합 단백질의 존재가 확인되었다. Parent는 본배양 0, 20, 44시간째에 합성 VB-C 300 ng/ml를 첨가시 초기 항생물질 생산시기가 약 8시간 이상 단축되었다. Transformant는 본배양 44시간에 첨가시 6시간 이상 항생물질 생산시기가 단축되었고 항생물질 생산량도 증가되었으며, parent에 비해 B. subtilis에도 강한 항균력을 나타내었다. 또한 항균 spectrum은 parent보다는 transformant가 생산한 항생물질의 항균호과가 더 큰 것으로 나타났으며, VB-C를 첨가한 경우 미첨가 경우보다 넓은 항균 spectrum을 보였다. 이들 결과에서 공시균인 S. erythraeus에서 VB signal 전달에 따른 항생물질 생산유도가 입증되었으며, VB-C receptor gene의 도입에 따른 발현과 함께 VBs의 유도, 항생물질의 생산시기의 단축 및 생산량의 증가가 예상됨에 따라 다양한 Streptomyces sp. 균주를 대상으로 항생물질의 대량생산을 비롯한 새로운 2차 대사산물 생산에의 응용이 예상되었다.

• 한국버섯학회지
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• 제12권3호
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• pp.171-180
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• 2014

느타리버섯류(Pleurotus spp.) 우량 품종개발에 많이 이용되는 교잡육종법 중에서 단핵-단핵간(mono-mono) 교잡에 관한 특성을 구명하기 위하여 느타리 6계통 및 사철느타리 1계통으로 단핵-단핵간 7조합 85개 교잡주를 얻어 교잡율, 핵 DNA 패턴 양상, 자실체의 갓 색깔과 수량성을 분석한 결과는 다음과 같다. 단핵-단핵간 교잡율은 50~93.75%로 나타났으며, 단핵간 85 교잡주의 핵 DNA 양상을 분석한 결과 양친주의 핵을 공유하고 있어 DNA 패턴은 양친의 중간이지만 유전유사도는 어느 한쪽 친주와 조금 더 가까운 양상을 나타냈다. 계통간교잡주 모두 양친의 핵이 공존하는 DNA 패턴을 나타내었지만 양친 중 한쪽 친과 유연관계가 가까운 것으로 나타났다. 사철느타리와 느타리간 교잡주는 유사도가 사철느타리에 가까웠고, 느타리간의 교잡주도 한쪽 모균주에 가까운 유연관계로 나타났다. 단핵-단핵간 교잡에서 자실체 갓 색은 사철느타리와 느타리간 교잡주는 대부분 양친주의 중간정도의 색을 나타냈으나 양친주 중 어느 한 쪽 친주에 좀 더 가까운 갓 색을 띄는 경향을 나타냈다. 자실체 수량성은 느타리간의 교잡주는 양친과 유사한 것이 82 %, 양친보다 높은 것이 0%, 양친보다 낮은 것이 18%였다. 본 연구는 느타리 계통간 교잡주의 핵 DNA 양상과 자실체 특성을 구명하였다. 단핵-단핵간 교잡법의 장점을 충분히 활용하여 앞으로 육종방법으로서 느타리버섯류의 우량 품종을 개발하는데 유용하게 이용될 수 있을 것으로 기대된다.

• 미생물학회지
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• 제36권4호
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• pp.259-266
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• 2000

아닐린분해능이 있는 Flavimonas oryzihabitans과 4-chlorobiphenyl (4-CBP)를 분해하는 Pseudomonas sp.를 원형질체 융합하여 아닐린과 4-CBP를 모두 분해하는 융합균주를 개발하고, 융합체의 특성을 조사하였다. F. oryzibhavitans는 융합체 선별표지 위애 NTG처리하여 chloramphenicol 내성 ($Cm^r$)을 유발하였다. Lysozyme-EDTA에 의한 각 모균주의 원형질체 생성율은 약 99%이었고, 원형질체의 재생율은 5.0~6.6%이었다. 원형질체는 40% PEG 6000을 사용하였을 때 효과적으로 융합이 이루어졌으며 융합율은 $3.16{\times}10^{-4} $이었다. 융합균인 F22의 DNA양는 모균주에 비해 약 2배 정도 증가 하였으며, 생화학적 특성은 모균주의 특성이 혼합하여 나타났다. F22는 5 mM 아닐린 최소배지에서는 모균주와 성장능과 분해능이 거의 비슷하였고, 10 mM 아닐린 최소배지에서는 1.5배 빠른 성장속도를 나타내었으나, 4-CBP 분해능은 모균주보다 약간 낮게 나타났다.

• 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.

• Journal of Microbiology and Biotechnology
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• 제3권2호
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• pp.78-85
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• 1993

In order to elucidate the mechanism which regulates the production of cyclodextrin glucanotransferase (CGTase) and to achieve overproduction of CGTase by releasing catabolite (glucose) repression, several catabolite repression resistant mutants were selected from newly screened Bacillus firmus var. alkalophilus H609, after NTG (N-methyl-N -nitro-N-nitrosoguanidine) treatment, using 2-deoxyglucose as a nonmetabolizable analog of catabolite glucose and as a selection marker. Five catabolite repression resistant mutants were selected from about 30, 000 2-deoxyglucose resistant colonies. Relative catabolite repression indices of the selected mutants were in the range of 8~80% assuming 100% for parent strain. The amount of CGTase produced by the mutant strain CR41, which was 250 units/ml, was three times larger than that produced by its parent strain. The mutation seems to have occurred in the regulatory region of CGTase gene and not in the structural region or the glucose transporting system in cell membrane. The enzymatic properties of CGTase excreted from parent and mutant strains were also compared.

• Journal of Microbiology and Biotechnology
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• 제4권2호
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• pp.155-159
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• 1994

Two Zymomonas mobilis strains (ZM63 and ZM6307), containing both lactose and galactose operons, were constructed. $\beta$-Galactosidase and galactokinase assays indicated that both operons were expressed in both strains. The transport systems available for lactose uptake by Zymomonas mobilis were investigated using $^{14}C$-labelled lactose. After the outer membrane, which was considered to be a possible barrier to lactose uptake, was disrupted by treatment with EDTA and $Ca^{2+}$ ions, some increase in lactose uptake was observed in ZM6306 ($lac^+$) and ZM6307 ($lac^+\;gal^+$), but not in the parent, ZM6. This suggested that the outer membrane of Zymomonas mobilis acts as a barrier to lactose uptake to some degree, and also that the lactose permease is operational in Zymomonas mobilis.

• Journal of Microbiology and Biotechnology
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• 제1권1호
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• pp.12-16
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• 1991

Previously RP1::Tn951 which is a derivative of RP1 containing the lactose transposon Tn951 was introduced into Z. mobilis strain ZM6l00, and RP1::Tn951 was integrated into its genome to yield ZM6306. The galactose operon was incorporated into ZM6306 to yield ZM6307 for more efficient utilization of lactose. Batch culture study has been carried out on Z. mobilis strains, ZM6306 ($lac^+$ ) and ZM6307 ($lac^+$ , $gal^+$ ), which can convert lactose directly to ethanol. Using a medium containing 80 gㆍ$1^{-1}$ glucose and 40 gㆍ$1^{-1}$ lactose, it was found that ZM6306 and ZM6307 produced maximum ethanol concentration of 40 gㆍ$1^{-1}$ and 42 gㆍ$1^{-1}$, respectively, whereas parent strain ZM6 produced 37 gㆍ$1^{-1}$.