• Journal of Life Science
• /
• 제9권1호
• /
• pp.14-16
• /
• 1999

Genetic variability was monitored by random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) in dicofol-susceptible (S), dicofol-resistant (R) and its reverse-selected (RS) strains of two-spotted spider mite, of Tetranychus urticae. Before the reverse-selection, RS strain, selected reversely from R strain, was 23-fold resistance ratio at {TEX}$LC_{50}${/TEX} to S strain. The resistance was started to in incline slowly to the resistance level of S strain after one year, and the resistance ratio was 4-fold in the 7 years after then. PCR-amplification of T. urticae DNA showed polymorphism in the amplifications with 12 primers in 100 kinds of arbitrary DNA sequences. RAPD amplification with primer OPR-12 (5`-ACAGGTGCGT-3`) showed amplified bands at 1,000 base pair in the S-and RS-strain, and at 350 base pair in R-strain. The results of polymorphism are genetic variabilities derived from development and selection of resistance in each strain. The peculiarly amplified fragments were guessed to participate in dicofol resistance. From the analysis of genetic similarity, it is inferred the gene composition of S-and RS-strain is much closer than that of R-strain.

• 한국미생물·생명공학회지
• /
• 제19권4호
• /
• pp.343-347
• /
• 1991

Tobramycin 고생산성 변이주를 쉽고 신속하게 선별하 수 있는 screening 방법을 개발하였다. 고농도의 apramycin이 포함된 배지를 사용함으로서 nebramycin 생산성이 낮은 변이주들은 1차적으로 제거할 수 있었다. 모균주인 S. tenerbarius ATCC 17920에는 저지환을 나타내지 못하고 생산성이 향상된 변이주의 경우에만 저지환을 형성하는 strain No.23을 토양으로부터 분리하여 Ps. paucimobilis로 동정하였고 1차 선별된 변이주들 중 tobramycin 생산성이 높은 균주들을 선별하기 위한 피검균으로 사용하였다. 이러한 screening 전략으로 strain No.23에 명확히 저지환을 나타내는 변이주 58주를 얻었고, HPLC를 이용하여 각 변이주의 tobramycin 생산성을 비교 측정한 결과 모균주에 비해 3-8배 생산성이 향상되었음을 확인하였다.

• Biomolecules & Therapeutics
• /
• 제1권1호
• /
• pp.26-30
• /
• 1993

Strain of treptomyces minoensis DMCJ-144 was tried to be improved so that it produces much more the $\alpha$-amylase inhibitor. Streptomyces minoensis DMCJ-144 was treated with 1 mg/mι (pH 9.0) of N-methyl-N'-nitro-N-nitrosoguanidine at $30^{\circ}C$ for 60 min and irradiated with UV light distanced 30 cm for 20 min. After mutagenesis, surviving colonies were cultured on the CM contaning acriflavine ($10{\mu}g/ml$) three times in order to enhance the mutability. And then through multi-level screening, colonies that ${\alpha}$-amylase inhibitor productibility. was Improved were selected by modified-blue value method. After third acriflavine treatment, $\alpha$-amylase inhibitory activities of selected colonies were found to be much better as compared with that of parent strain. One mutant strain showed 5.4 time inhibitory activity than the parent strain.

• 한국미생물·생명공학회지
• /
• 제31권2호
• /
• pp.205-209
• /
• 2003

Recently, we introduced a new method for rapid screening of bacterial species- or subspecies-specific DNA probes, named “inverted dot blot hybridization screening method”. We then applied this method to develop species- or strain- specific DNA probes for Prevotella intermedia and Prevotella nigrescens. In those studies, among 96 candidate DNA probes which were screened by the new method, 5 probes were confirmed as being putatively strain-specific : 3 probes for P. nigrescens 9336 (ATCC 33563), one for each p. intermedia ATCC 25611 and one for P. nigrescens G8-9K-3 (ATCC 49046). In the present study, we evaluated by Southern blot analysis a DNA probe Pi29-L, one of the 96 candidate probes described above, whether it is specific for the strain ATCC 25611 off. intermedia. Our data show that the probe Pi29-L is potentially P. intermedia ATCC 25611-specific, which can be useful for the detection and identification of the strain, particularly in maintenance of the strain.

• Journal of Microbiology and Biotechnology
• /
• 제14권2호
• /
• pp.422-425
• /
• 2004

To discover a potent strain against wheat leaf rust, soil samples collected from Ilgamho, Seoul, Korea were tested in vivo and a strain belonging to Streptomyces sp. was found to show good antifungal activity when fermented in a broth. The identification of the strain was carried out based on 16S rDNA analysis, and the active compound was separated from the fermented broth. Even though its structure was not determined completely, the authors report the results obtained so far indicate that the fermented broth of the strain showed activity against wheat leaf rust. Therefore, we propose that this may be a potential novel strain showing antifangal activity against Puccinia recondita.

• Journal of Microbiology and Biotechnology
• /
• 제12권6호
• /
• pp.1026-1028
• /
• 2002

Screening tests against fungus causing rice blast, Magnaporthe grisea, were performed in order to develop biopesticides. More than 400 actinomycetes collected at several sites near Hanla Mountain on Jeju Island, Korea were tested, and strain BG2-53 showed potent antifungal activity. The in vivo screening was performed with fermentation broth, and the strain taxon was identified.

• 약학회지
• /
• 제28권2호
• /
• pp.89-95
• /
• 1984

Microorganisms having beta-latamase inhibitory activity were selected from soil samples collected from 63 spots throughout the country. Screening procedures consist of two steps. Those are growth inhibition test of penicillinase-producing Staphylococcus aureus by double-layered agar plate containing penicillin G as a substrate, and that of penicillin sensitive Staphylococcus aureus ATCC 6538 in the similiar condition including penicillinase. Finally, a strain was selected from a soil sample of Pa-ju, Kyeong-gi Do. This strain was classified as a Streptomyces sp. by ISP(International Streptomycete Project) and Bergey's manual.

• 한국미생물·생명공학회지
• /
• 제23권4호
• /
• pp.405-410
• /
• 1995

In order to screen dextranase with high dextranolytic activity from microbial origins, dextranase producing fungal isolates were isolated from soil of the Taeion area. 197 strains with dextranolytic activities were isolated, out of which 3 strains with high dextranolytic activities were selected in the first screening. A strain (GR-98) with a best dextranolytic activity was selected in the second screening. The strain was identified to be similiar Aspergillus ustus by the morphological and cultural characteristics. The optimum culture temperature and initial pH for the dextranase production of the strain was 30$\circ$C and 7.0, respectively. The optimum culture medium was composed of 2% dextran, 0.3% KNO$_{3}$, 0.05% K$_{2}$HPO$_{4}$, 0.02% MgSO$_{4}$-7H$_{2}$O, 0.05% KC1, and 2.5 $\mu$g/ml pyridoxamine, and the enzyme production was maximum when the strain was subcultured at 30$\circ$C for 7 days.

• 대한바이러스학회지
• /
• 제29권3호
• /
• pp.175-182
• /
• 1999

An attractive target for anti-herpes chemotherapy is the herpes simplex virus 1 (HSV-1) protease encoded by the UL26 gene. HSV-1 protease is essential for DNA packaging and virus maturation. To perform high throughput for potent inhibitors, the efficient production of larger amounts of highly purified enzyme and protease activity assay method must be established. In this report, expression in E. coli and purification of the protease gene of HSV-1 strain F was investigated. The protease gene was cloned pET28, and the nucleotide sequence of protease catalytic domain of HSV-1 compared strain F with other strains (KOS and CL101). In these results the F strain was different in base sequence. However, the amino acid sequence was identifical. The HSV-1 protease was purified with His-tagged affinity column. The analysis of HSV-1 protease activity was performed by high performance liquid chromatography.

• 한국미생물·생명공학회지
• /
• 제17권2호
• /
• pp.115-120
• /
• 1989

세포외로 pepsin 저해물질을 생산하는 미생물을 획득할 목적으로 screening test를 실시하여, porcine pepsin에 대하여 우수한 저해력을 나타내는 방선균 1균주(GF 155-2)를 분리하였다. 각종 배지상에서 그 형태학적·배양학적·생리학적 성질을 조사하여 본 결과 그 미생물학적 특성이 Microtetraspora속과 유사하였다.