• 한국미생물·생명공학회지
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• 제23권4호
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• pp.411-415
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• 1995

The dextranase (EC 3.2.1.11) produced by Aspergillus ustus GR-98 was purified by the following sequential methods; salting-out and dialysis, gel filtration on BIO-GEL P-100, ion exchange chromatography on DEAH-cellulose, affinity chromatography on hydroxyapatite, and preparative electrophoresis. Three active fractions, dextranases 1, 11 and 111, were isolated in electrophoretically pure states, and specific activities of the dextranases were 1,276, 1,154 and 1,125 units/mg, the degrees of yield were 9.0, 3.6 and 2.2%, having 145, 131.1 and 127.8 times as those of culture filtrate in degree of purification, respectively. The enzyme purity was confirmed by the PAGE, SDS-PAGE and get permeation-HPLC.

• Journal of Microbiology and Biotechnology
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• 제21권7호
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• pp.686-696
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• 2011

To deal with pathogens, plants have evolved sophisticated mechanisms including constitutive and induced defense mechanisms. Phytohormones play important roles in plant growth and development, as well as in the systemic response induced by beneficial and pathogen microorganisms. In this work, we identified an Aspergillus ustus isolate that promotes growth and induces developmental changes in Solanum tuberosum and Arabidopsis thaliana. A. ustus inoculation on A. thaliana and S. tuberosum roots induced an increase in shoot and root growth, and lateral root and root hair numbers. Assays performed on Arabidopsis lines to measure reporter gene expression of auxin-induced/ repressed or cell cycle controlled genes (DR5 and CycB1, respectively) showed enhanced GUS activity, when compared with mock-inoculated seedlings. To determine the contribution of phytohormone signaling pathways in the effect elicited by A. ustus, we evaluated the response of a collection of hormone mutants of Arabidopsis defective in auxin, ethylene, cytokinin, or abscisic acid signaling to the inoculation with this fungus. All mutant lines inoculated with A. ustus showed increased biomass production, suggesting that these genes are not required to respond to this fungus. Moreover, we demonstrated that A. ustus synthesizes auxins and gibberellins in liquid cultures. In addition, A. ustus induced systemic resistance against the necrotrophic fungus Botrytis cinerea and the hemibiotrophic bacterium Pseudomonas syringae DC3000, probably through the induction of the expression of salicylic acid, jasmonic acid/ethylene, and camalexin defense-related genes in Arabidopsis.

• 한국균학회지
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• 제11권1호
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• pp.23-26
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• 1983

Aspergillus ustus의 dextranase을 정제하기 위하여 냉각 Aceton에 침전시키고, DEAE-cellulose, Bio-Gel P-150 및 Sephadex G-200을 사용하며 순수정제하였다. 처음 배양액 10l에 대한 총 효소량은 1,340kunits 단백질 양은 38,500mg였으며, 최종정제 단계인 Sephadex G-200에서는 총 효소 활성량은 421 kunits, 단백질량은 172mg이었으며 비활성은 약 70배로 증가했다.

• 한국균학회지
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• 제11권1호
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• pp.15-21
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• 1983

정제된 Aspergillus ustus의 dextranase 특성을 조사하기 위하여 최적 pH 최적온도 및 열 안정성 금속이온의 영향 및 분해산물을 조사하였다. 기질로는 dextran을 사용했다. 조사결과 dextranase의 활성 최적 pH는 6.5였으며, 작용 최적온도는 $40^{\circ}C$이고, $30^{\circ}C{\sim}35^{\circ}C$에서 비교적 분해능이 좋았고, 열 안전성은 $50^{\circ}C$에서 1시간 처리한 경우 약 91%의 잔존역가를 나타내고, $70^{\circ}C$에서는 약 38%의 잔존역가를 나타내 $50^{\circ}C$까지는 안정한 것으로 나타났다. 금속이온 등의 영향은 cysteine, ascorbic acid와 EDTA에서 상승작용을 나타내고, $Cu^{2+},\;KCN,\;Co^{2+}$에서는 약한 저해 작용을 나타내고, $Hg^{2+}는 완전히 저해되었다. 덱스트란을 분해시킨 분해산물은 glucose와 isomaltotriose및 그 이상의 분자량을 가지는 oligosaccharide로 구성되어 있고, 치아부착 다당류에 대한 분해도 덱스트란과 유사하였다.

• 미생물학회지
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• 제18권4호
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• pp.188-192
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• 1980

In search of dextran-hydrolyzing enzymes, approximately 500 strains of molds were checked for their ability to produce extracellular dextranase. Seven strains capable of producing dextranase were screened, and among them, one strain belonging to Aspergillus genus showed greater activity than the other. The strain was identified to be Aspergillus ustus and the most suitable culture conditions for the enzyme production were determined.

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

• Mycobiology
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• 제33권2호
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• pp.77-83
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• 2005

Seventy-three fungal species belonging to forty-three genera were isolated from 40 samples of Saccharrum officinarum (collected from Naage-Hamadi canal in Qena Governorate, Egypt). Aspergillus, Trichoderma, Mucor and Pythium were the most common genera on the two isolation media. The dominant species of Aspergillus were A. niger, A. flavus, A. ustus, A. terreus and A. wentii. Some species were dominant on 40 g/l sucrose such as Aspergillus niger, A. flavus, Emericella nidulans, Trichoderma viride, Torula herbarum and Mamaria echinoeotryoides, while the dominant species on 10 g/l glucose were Mucor circinelloides, Aspergillus niger, Torula herbarum and Trichoderma viride. Mycotoxins including aflatoxins $B_1,\;B_2,\;G_1\;and\;G_2$, zearalenone and diacetoxyscirpenol were detected in the examined samples of Saccharrum officinarum. The mycelial growth of A. flavus, A. niger, Fusarium moniliforme and Torula herbarum decreased with the increase in Dimethoate concentrations, although 25 ppm was less effective than the higher levels of the insecticide ($75{\sim}200\;ppm$). Dimethoate stimulated the activity of Go-Tin A. niger, F. moniliforme and T. harbarum, while the Go-T activity was inhibited in A. flavus with the Dimethoate treatments.