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1.
Arch Microbiol ; 203(5): 2625-2637, 2021 Jul.
Article in English | MEDLINE | ID: mdl-33709160

ABSTRACT

This work aims at isolating a fungal source for L-asparaginase production to be applied in reducing acrylamide levels in coffee beans at non-cytotoxic levels. An L-asparaginase-producing fungus was isolated from an agricultural soil sample and identified as Penicillium crustosum NMKA 511. A maximum L-asparaginase activity of 19.10 U/mL was obtained by the above-mentioned fungus when grown under optimum conditions (i.e. 16.96 g/L sucrose as carbon source, 1.92 g/L peptone as nitrogen source, pH 7.7 and 33.5 °C). Further, the produced L-asparaginase was purified and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that P. crustosum L-asparaginase was a heterodimer enzyme with molecular weights of approximately 41.3 and 44.4 kDa. Also, the purified P. crustosum L-asparaginase was specific towards L-asparagine and showed negligible and no effects towards L-glutamine and D-asparagine, respectively. Additionally, the purified L-asparaginase reduced the acrylamide levels by 80.7% and 75.8% in light and dark roasted coffee beans, respectively. The amount of L-asparaginase used to reduce acrylamide was considered safe when cell viability reached 94.6%.


Subject(s)
Acrylamide/analysis , Acrylamide/metabolism , Asparaginase/metabolism , Coffea/chemistry , Penicillium/enzymology , Asparaginase/chemistry , Asparaginase/isolation & purification , Asparagine/metabolism , Electrophoresis, Polyacrylamide Gel , Glutamine/metabolism , Molecular Weight , Penicillium/isolation & purification , Seeds/chemistry , Soil Microbiology , Substrate Specificity
2.
J Microbiol Biotechnol ; 29(12): 1861-1872, 2019 Dec 28.
Article in English | MEDLINE | ID: mdl-31693831

ABSTRACT

In the present work, we isolated and identified Aspergillus sydowii NYKA 510 as the most potent laccase producer. Its medium constituents were optimized to produce the highest possible amount of laccase, which was after 7 days at 31°C and pH 5.2. Banana peel and peptone excelled in inducing laccase production at concentrations of 15.1 and 2.60 g/l, respectively. Addition of copper sulfate elevated enzyme yield to 145%. The fungus was employed in a microbial fuel cell (MFC). The best performance was obtained at 2000 Ω achieving 0.76 V, 380 mAm-2, 160 mWm-2, and 0.4 W. A project to design a self-sufficient lighting unit was implemented by employing a system of 2 sets of 4 MFCs each, connected in series, for electricity generation. A scanning electron microscopy image of A. sydowii NYKA 510 was utilized in algorithmic form generation equations for the design. The mixed patterning and patterned customized mass approach were developed by the authors and chosen for application in the design.


Subject(s)
Aspergillus/enzymology , Bioelectric Energy Sources , Laccase/metabolism , Lighting/methods , Algorithms , Aspergillus/genetics , Aspergillus/isolation & purification , Copper Sulfate/chemistry , Culture Media/chemistry , Electricity , Electrodes , Equipment Design , Lighting/instrumentation
3.
Chemosphere ; 218: 477-486, 2019 Mar.
Article in English | MEDLINE | ID: mdl-30497030

ABSTRACT

The cell-free culture filtrate (CFF) of the fungi Fusarium chlamydosporum NG30 and Penicillium chrysogenum NG85 was tested to synthesize silver nanoparticles (AgNPs). The synthesized AgNPs were further characterized by means of transmission electron microscopy (TEM), dynamic light scattering (DLS) and Fourier transform infra-red (FTIR) spectroscopy. TEM revealed their spherical shape, homogeneity and a size range between 6 and 26 nm for F. chlamydosporum AgNPs (FAgNPs) and from 9 to 17.5 nm for P. chrysogenum AgNPs (PAgNPs). DLS showed that the diameter of FAgNPs was narrower than that of PAgNPs. FTIR spectroscopy indicated that the functional groups present in the CFF might be responsible for the reduction of silver ions to form stabilized protein-capped AgNPs. In addition, the AgNPs showed notable antifungal activity and potency in thwarting mycotoxin production. Thus, using Aspergillus flavus as a test microorganism the minimum inhibitory concentration (MIC) was 48, 45 and 50 µg/mL for FAgNPs, PAgNPs and the antifungal compound itraconazole, respectively. Also, when testing Aspergillus ochraceus FAgNPs, PAgNPs and itraconazole led to MIC values of 51, 47 and 49 µg/mL, respectively. The statistical MIC values to inhibit completely the total aflatoxin production by A. flavus were 5.9 and 5.6 µg/mL for FAgNPs and PAgNPs, respectively, and to inhibit the ochratoxin A production by A. ochraceus 6.3 and 6.1 µg/mL for FAgNPs and PAgNPs, respectively. The cytotoxicity assay of the AgNPs on human normal melanocytes (HFB 4) revealed a cell survival of 80% and 75% at a concentration of 6 µg/mL for FAgNPs and PAgNPs, respectively.


Subject(s)
Antifungal Agents/pharmacology , Fusarium/metabolism , Metal Nanoparticles/chemistry , Penicillium chrysogenum/metabolism , Silver/pharmacology , Aflatoxins/metabolism , Antifungal Agents/metabolism , Aspergillus flavus/drug effects , Aspergillus flavus/metabolism , Aspergillus ochraceus/drug effects , Aspergillus ochraceus/metabolism , Cell-Free System , Dynamic Light Scattering , Fusarium/cytology , Humans , Melanocytes/drug effects , Metal Nanoparticles/toxicity , Microbial Sensitivity Tests , Microscopy, Electron, Transmission , Ochratoxins/metabolism , Penicillium chrysogenum/cytology , Silver/chemistry , Spectroscopy, Fourier Transform Infrared , Toxicity Tests
4.
Saudi J Biol Sci ; 18(2): 117-21, 2011 Apr.
Article in English | MEDLINE | ID: mdl-23961113

ABSTRACT

Sodium dodecyl sulfate-polyacrlyamide gel electrophoresis (SDS-PAGE) was used to assess the purity and molecular weight of the previously purified alkaline keratinase enzyme of Scopulariopsis brevicaulis. The enzyme was homogenous, as seen by a single band of protein, and had an apparent molecular weight of 28.5 kDa. Amino acid profile of the purified keratinase revealed that it was composed of 14 different amino acids with high proportions of glutamic acid (20.86%), alanine (14.52%), glycine (14.21%), leucine (8.59%) and serine (7.81%). The enzyme contained moderate amounts of valine (6.01%), threonine (5.58%) and phenyl alanine (5.22%). The purified enzyme of S. brevicaulis exerted a potent keratinolytic activity and was capable to hydrolyze different keratinaceous materials with highest activity on chicken feathers followed by human nails and human hair.

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