• The Korean Journal of Mycology
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• v.17 no.3
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• pp.145-148
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• 1989

An acid-stable ${\alpha}-amylase$ produced by Aspergillus niger K-25 strain was purified by fractional precipitation with ammonium sulfate, ethacridine and acetone. The final preparation was homogeneous in cellulose acetate electrophoresis. The enzyme retained 91 % of its oringinal activity at pH 3.0, 8.7% at pH 2.4. The optimum pH of the enzyme was around pH 4. The purified-enzyme with optimum temperature of $40^{\circ}C$ was more heat-stable than the commercial product. The enzyme retained 80% of its original activity when heated to $60^{\circ}C$ for 30 minutes while the commercial amylase lost its acitivity completely within 30 minutes at $50^{\circ}C$.

• Applied Biological Chemistry
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• v.25 no.4
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• pp.257-260
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• 1982

During the rice storage at $28^{\cir}{\pm}1^{\cir}C$ and $60{\sim}70%$ R.H., the moisture content of rice, was increased max. 1. 6% by the activity of rice weevil. The growth of Asp. repens was not affected, while Asp. niger was inhibited after the appearance of its second generation adults. The development of rice weevil was generally accelerated by both of Asp. repens and Asp. niger, but decelerated at higher density of Asp. niger($1.6{\times}10^4$ propagules/g). The total number of rice weevil showed no significant difference during six weeks.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.37 no.4 s.112
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• pp.1-7
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• 2005

This study was carried out to investigate the characteristics of extracellular cellulase and xylanase from Fusarium pallidoroseum and Aspergillus niger, such as enzyme activity and stability by various pH, temperature and metal ions, for application into enzymatic deinking system. The optimal temperature and pH for enzyme activity and stability of Fusarium pallidoroseum and Aspergillus niger were $50^{\circ}C$, pH 5.0 and $60^{\circ}C$, pH 9.0, respectively. Certain metal ions, calcium and cobalt, brought to elevate cellulase and xylanase activity from F. pallidoroseum and A. niger. With these results we suggest that enzymatic deinking system should be proceed at $50\~60^{\circ}C$ under their optimal pH condition.

• Mycobiology
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• v.33 no.2
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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.

• Journal of Microbiology and Biotechnology
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• v.25 no.1
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• pp.11-17
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• 2015

In an attempt to shift the optimal pH of the xylanase B (XynB) from Aspergillus niger towards alkalinity, target mutation sites were selected by alignment between Aspergillus niger xylanase B and other xylanases that have alkalophilic pH optima that highlight charged residues in the eight-residues-longer loop in the alkalophilic xylanase. Multiple engineered XynB mutants were created by site-directed mutagenesis with substitutions Q164K and Q164K+D117N. The variant XynB-117 had the highest optimum pH (at 5.5), which corresponded to a basic 0.5 pH unit shift when compared with the wild-type enzyme. However, the optimal pH of the XynB-164 mutation was not changed, similar to the wild type. These results suggest that the residues at positions 164 and 117 in the eight-residues-longer loop and the cleft's edge are important in determining the pH optima of XynB from Aspergillus niger.

• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.2
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• pp.89-94
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• 2002

The continuous production of citric acid from dairy wastewater was investigated using calcium-alginate immobilized Asrergillus niger ATCC 9142. The citric acid productivity and yield were strongly affected by the culture conditions. The optimal pH, temperature, and dilution rate were 3.0, 30$^{\circ}C$, and 0.025 h$\^$-1/, respectively. Under optimal culture conditions, the maximum productivity, concentration, and yield of citric acid produced by the calcium-alginate immobilized Aspergillus niger were 160 mg L$\^$-1/ h$\^$-1/, 4.5 g/L, and 70.3%, respectively, The culture was continuously perfored for 20 days without any apparent loss in citric acid productivity. Conversely, under the same conditions with a batch shake-flask culture, the maximum productivity, citric acid concentration, and yield were only 63.3 mg L$\^$-1/h$\^$-1/, 4.7 g/L and 51.4%, respectively, Therefore, the results suggest that the bioreactor used in this study could be potentially used for continuous citric acid production from dairy wastewater by applying calcium-alginate immobilized Aspergillus niger.

• Journal of Ginseng Research
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• v.38 no.1
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• pp.47-51
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• 2014

The transformation of ginsenoside Rb1 into a specific minor ginsenoside using Aspergillus niger KCCM 11239, as well as the identification of the transformed products and the pathway via thin layer chromatography and high performance liquid chromatography were evaluated to develop a new biologically active material. The conversion of ginsenoside Rb1 generated Rd, Rg3, Rh2, and compound K although the reaction rates were low due to the low concentration. In enzymatic conversion, all of the ginsenoside Rb1 was converted to ginsenoside Rd and ginsenoside Rg3 after 24 h of incubation. The crude enzyme (b-glucosidase) from A. niger KCCM 11239 hydrolyzed the ${\beta}$-($1{\rightarrow}6$)-glucosidic linkage at the C-20 of ginsenoside Rb1 to generate ginsenoside Rd and ginsenoside Rg3. Our experimental demonstration showing that A. niger KCCM 11239 produces the ginsenoside-hydrolyzing b-glucosidase reflects the feasibility of developing a specific bioconversion process to obtain active minor ginsenosides.

• Journal of Life Science
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• v.20 no.7
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• pp.999-1004
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• 2010

Investigations were carried out on a $\beta$-glucosidase produced by Aspergillus niger under solid-state fermentation conditions as a model of enzyme recovery from fermented wheat bran. The leaching efficiency of distilled water to recover the enzyme from the fermented bran was higher than acetate buffer, citrate buffer, citrate-phosphate buffer and 5% methanol; thus, the conditions were further optimized with distilled water as the extracting agent. After fermented bran was washed three times with distilled water for 1.5 hr each under shaking conditions at 1:5 solid to solvent ratio, a maximum recovery of 0.025 U/g of wheat bran was obtained.

• Journal of Microbiology and Biotechnology
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• v.11 no.6
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• pp.1066-1070
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• 2001

The PhyA gene, encoding myo-inositol hexakisphosphate phosphohydrolase in Aspergillus niger var. awamori (wild-type), was cloned and sequenced. The cDNA was overexpressed by a multicopy gene expression system in Pichia pastoris KM71. Recombinant, wild-type and commercial phytase from Aspergilus ficuum NRRL 3135 (Natuphos) were purified. The PhyA gene of Aspergillus niger var awamori showed perfect homology to the phytase of Aspergillus ficcum and $97\%$ homology to A. niger var awamori (L02421). Wild-type phytase was highly glycosylated and more thermostable than the other two, while deglycosylated farms of three phytases showed identical molecular weight, 507 kDa. After heating at $80^{\circ}C$, wild-type, commercial, and recombinant phytases retained $57\%, 32%,\;and\;8\%$ of their original activities, respectively. In conclusion, glycosylation plays a key role in the thermostability of phytase and its enzymatic characterization.

• Korean Journal of Microbiology
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• v.14 no.1
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• pp.17-24
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• 1976

Celluloytic microorgnasims were isolated form the various sources and four of them were identified as Trichoderma roningi, Aspergillus niger, Penicillium chrysogenum, and Streptomyces sp. The induction of extracellular5 cellulase of these species in the liquid culture media containing carboxymethylcellulose (CMC) or Avicel as inducer showed that CMC was a better effective inducer for the production of CMCase(Cx cellulase component) as well as Avicelase(C$_{1}$ cellulase component) than Avicel. It is believed that certain hydrolysis products of cellulose(CMC) could serve as an inducer for an enzyme synthesis. In T. roningi, Asp. niger, and Strptomyces sp., the optimum temperature of CNCase on CMC-culture medium was 50.deg. but temperature around 40.deg.C was found to be optimum for the activities of CMCase prepared from P.ehrysogenum. The optimum temperature for Avicelase activitiles on Avicel-culture media of T. roningi and P. chrysogenum was $40{\circ}C$ whereas temperature $50{\circ}C$ was found to be optimum for Avicelase from A.niger and Streptomyces sp. The optimal activities of these CNCase and Avicelase prepared from. T. ronigi, Pen.chrysogenum and Streptomyces sp. were found similarly to be at pH's around 5.4 and 6.0 while pH 4.8 was optimum for the activities of CMCase and Avicelase from A.niger, indicating that A.niger in acidic media would yield an enzyme of high activity.