• Food Science and Biotechnology
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• 제18권3호
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• pp.655-660
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• 2009

Biotechnological phytase preparations are commercially available and are currently used in animal feeding. However, thermostability constraints, low yields, and the high cost of the enzyme have limited its use. This study represents a new perspective for the food enzyme market. The research screened thermostable yeast strains for their ability to produce phytase. The screening was carried out with a gradual increase in temperature ($30-48^{\circ}C$). Sixteen strains (1 strain identified as Saccharomyces cerevisiae) maintained the ability to produce phytase at $48^{\circ}C$ and their phytase activity was confirmed using 2 phytase assay methodologies. The yeast strains tested in this study seem to be potential efficient producers of phytase, indicating a possible new source of thermostable phytase of commercial interest, particularly that from S. cerevisiae.

• Journal of Microbiology and Biotechnology
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• 제14권1호
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• pp.220-223
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• 2004

Club root caused by Plasmodiophora brassicae is found in crucifers. Among the over hundreds of Streptomyces isolated from soil in Korea. One strain showed prominent activity against P. brassicae. The strain was identified based on 16S rDNA sequencing and the morphology by a method of scanning electron microscopy. An active compound in the fermented broth obtained from the strain was separated. Even though the complete assignments of the compound remain for future work, the results regarding the isolation and characterization of the strain with a certain activity against P. brassicae are shown in this paper.

• Mycobiology
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• 제49권1호
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• pp.54-60
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• 2021

During the screening of Korean microflora, a fungal strain (KNU-PT-1804) belonging to the genus Pestalotiopsis was isolated from persimmon tree (Diospyros kaki) bark collected from North Gyeongsang Province, Korea. The strain, KNU-PT-1804, produced smaller conidia compared with related species P. kenyana, P. neglecta, and P. telopeae. The novelty of the strain was confirmed based on phylogenetic analysis using molecular datasets of internal transcribed spacer (ITS) regions, β-tubulin (TUB2), and translation elongation factor 1-alpha (TEF1α) genes. Molecular phylogeny strongly supports that the strain is distinct from previously known Pestalotiopsis species, and we proposed the novel species, Pestalotiopsis kaki sp. nov., and provide a detailed description and illustration.

• KSBB Journal
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• 제28권3호
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• pp.213-215
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• 2013

A high-throughput screening strategy was developed to simplify the selection process for improved mannitol producing strain after chemical mutagenesis. Ethylmethyl sulfonate (EMS) was used as a chemical mutagen to alter the fructokinase-I gene which is an essential enzyme to metabolize fructose for growth. Leuconostoc mesenteroides treated with EMS were plated on the modified MRS solid medium containing fructose as a sole carbon source. Strains showing inhibited growth were primarily selected to evaluate the mannitol producing ability. By applying this strategy, L. mesenteroides ATCC 8293 M1, L. mesenteroides ATCC 9135 M3 and L. mesenteroides D1 M3 showed improvement in mannitol production.

• KSBB Journal
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• 제14권2호
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• pp.235-240
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• 1999

Trigonopsis variabilis ATCC10679 (TW)의 변이균주를 선별하기 위하여 쉽고 간편한 균주 선별방법을 개발하였다. 변이 균주(T26)의 D-Amino acid oxidase (D-AAO)는 야생균주(TW)의 D-AAO 효소보다 cephalosporin C에 대한 기질특이성이 약 30% 높았다. 이들 두 균주에서 D-AAO 유전자를 클로닝하여 각 유전자를 비교해본 결과 811번 우치의 T가 C로 변경되었으며 이에 따른 아미노산은 Phe-258이 Ser-258로 바뀌었다.

• Journal of Microbiology
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• 제45권3호
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• pp.262-267
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• 2007

During a screening program, an actinomycete strain isolated from the Egyptian soil was investigated for its potential to show antimicrobial activity. The identification of this isolate was performed according to spore morphology and cell wall chemo-type, which suggested that this strain is a streptomycete. Further cultural, physiological characteristics and the analysis of the nucleotide sequence of the 16S rRNA gene (1480 bp) of this isolate indicated that this strain is identical to Streptomyces violaceusniger (accession number EF063682) and then designated S. violaceusniger strain HAL64. In its culture supernatant, this organism could produce one major compound strongly inhibits the growth of Gram-positive but the inhibition of Gram-negative indicator bacteria was lower. The antibiotic was separated by silica gel column chromatography and then purified on a sephadex LH-20 column and finally the purity was checked by HPLC. The chemical structure of the purified compound was determined using spectroscopic analyses (molecular formula of $C_{33}H_{32}N_{2}O_{10}$ and molecular weight of 617.21) and found to be identical to the kosinostatin, a quinocycline antibiotic which is known to be produced by Micromonspora sp. TP-A0468 (Igarashi et al., 2002) and to quinocycline B isolated from Streptomyces aureofaciens (Celmer et al., 1958). Although the antibiotic is known, the newly isolated strain was able to produce the antibiotic as a major product providing an important biotechnological downstream advantage.

• Journal of Microbiology and Biotechnology
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• 제21권4호
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• pp.374-378
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• 2011

To find alternative genetic resources for D-serine dehydratase (E.C. 4.3.1.18, dsdA) mediating the deamination of D-serine into pyruvate, metagenomic libraries were screened. The chromosomal dsdA gene of a wild-type Escherichia coli W3110 strain was disrupted by inserting the tetracycline resistance gene (tet), using double-crossover, for use as a screening host. The W3110 dsdA::tet strain was not able to grow in a medium containing D-serine as a sole carbon source, whereas wild-type W3110 and the complement W3110 dsdA::tet strain containing a dsdA-expression plasmid were able to grow. After introducing metagenome libraries into the screening host, a strain containing a 40-kb DNA fragment obtained from the metagenomic souce derived from a compost was selected based on its capability to grow on the agar plate containing D-serine as a sole carbon source. For identification of the genetic resource responsible for the D-serine degrading capability, transposon-${\mu}$ was randomly inserted into the 40-kb metagenome. Two strains that had lost their D-serine degrading ability were negatively selected, and the two 6-kb contigs responsible for the D-serine degrading capability were sequenced and deposited (GenBank code: HQ829474.1 and HQ829475.1). Therefore, new alternative genetic resources for D-serine dehydratase was found from the metagenomic resource, and the corresponding ORFs are discussed.

• 한국미생물·생명공학회지
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• 제20권3호
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• pp.335-343
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• 1992

미생물이 생산하는 대사길항물질을 screening한 결과 최소검정배지에서 Gram 양성균에 항균활성을 나타내고 L-leucine에 의하여 그 항균활성이 길항당하는 182-27 물질을 생산하는 방선균을 토양에서 새로이 분리하였다. 본 생산균을 분류 동정한 결과, 유연균을 찾아볼 수가 없고 신 균종으로 동정하기에는 많은 type culture와의 비교분류를 하여야만 하므로 여기서는 다만 기균사의 포자형성과 세포벽 성분의 조성, 형태학적 성상 등으로 보다 Streptomyces sp.로만 동정하였다. 182-27 균주의 배양조건을 검토하고 최적조건에서 대량 배양하여 그 배양여액으로부터 이온교환수지, silica gel column chromatography 등에 의하여 활성 물질을 분리 정제하였으며 배양액 약 20$\ell$에서 약 20mg의 백색분말을 얻었다. 182-27 물질은 그의 이화학적 성질로 보아 아미노산 유연물질로 추정할 수가 있으나 그의 화학구조는 아직 밝히지 못했다. 생물학적 성질은 최소검정배지상에서 Gram 양성균에 항균력을 나타냈고 이러한 항균력은 L-leucine의 첨가에 의해 저해 당했다.

• 한국유기농업학회지
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• 제5권1호
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• pp.137-147
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• 1996

For the purpose of acquiring microbial agents that can be utilized to biologically control the major airborne diseases to apple trees, such as canker(Botryosphaeria dothidea), bitter rot(Glomerella cingulata), alternaria leaf spot(Alternaria mali), root rot(rosellinia necatrix), canker(Valsa ceratosperma) and gray mold rot(Botrytis cinerea), the effective microorgaisms were isolated, tested for antagonistic activity to the pathogens causing major diseases to apple trees and identifed. Screening of more than 5,000 species of microorganisms collected in nature for them antagonistic action to the pathogens causing 5 major diseases to apple trees resulted in selection of effective species. Out of the 11 species, one species designated as CAP134 demonstrated outstanding activity. The bacterial strain, CAP134 exerted antagonistic efficiency of 57% on an isolated strain and 40% on a donated strain of Botryosphaeria dothidea., 52% on an isolated strain and 46% on a purchased strain of Alternaria mali, 60% on Valsa ceratosperma 25% on Glomerella cingulata, and 64% Rosellinia necatrix. The CAP134 was identified as a bacterial strain to Bacillus subtilis ATCC 6633 based on morephology, culture conditions, and physio-biochemical characteristics.

• 한국미생물·생명공학회지
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• 제20권1호
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• pp.110-113
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• 1992

In the screening process of anti- or desmutagenic substance from the various microbial metabolites with the method of Ames and Rec-assay, a desmutagenic substance producing bacterial strain which inactivates the mitomycin C-induced mutagenicity was isolated and identified as Psudomonas sp. AM-10.