Freeing anomeric hydroxyl groups of peracetylated oligosaccharides by Aspergillus niger lipase

2002 ◽  
Vol 43 (28) ◽  
pp. 4939-4942 ◽  
Author(s):  
Assunta Giordano ◽  
Antonio Trincone
Keyword(s):  
Aspergillus Niger ◽  
Hydroxyl Groups

scholarly journals Substrate Hydroxyl Groups Are Involved in the Ionization of Catalytic Carboxyl Groups of Aspergillus niger .ALPHA.-Glucosidase

2004 ◽  
Vol 51 (1) ◽  
pp. 9-14 ◽  
Author(s):  
Masahiro Ogawa ◽  
Toshiyuki Nishio ◽  
Wataru Hakamata ◽  
Yukari Matsuishi ◽  
Shigeki Hoshino ◽  
...  
Keyword(s):  
Aspergillus Niger ◽  
Carboxyl Groups ◽  
Hydroxyl Groups ◽  
Alpha Glucosidase

scholarly journals Biosynthesis of Zinc Oxide (ZnO) Using Culture Biomass of Aspergillus Niger : The Influence of pH On Textile Morphology And Antimicrobial Activity

2021 ◽  
Author(s):  
Yetria Rilda ◽  
Rifki Rinaldi ◽  
Syukri Syukri ◽  
Armaini Armaini ◽  
Refinel Refinel ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Zinc Oxide ◽  
Aspergillus Niger ◽  
Sol Gel ◽  
Inhibition Zone ◽  
Antibacterial Activities ◽  
Hydroxyl Groups ◽  
Cell Biomass ◽  
A Value ◽  
Size And Morphology

Abstract The biosynthesis of zinc oxide (ZnO) is performed through enzymatic mechanisms, by controlling the particle size and morphology of the compound using the sol-gel method. Furthermore, this method utilizes stabilizer obtained from the cell biomass of Aspergillus niger bacteria, in order to yield homogeneous and consistent products, which corresponds with the XRD outcome that exhibits good crystallinity. The evaluation of functional, morphological, and antibacterial activities was carried out at pH 6.0-13.0, as the prepared samples were characterized by FT-IR. The analysis showed the interaction of hydroxyl groups, aromatic rings, as well as N-H and O-Zn-O compounds at a wavenumber of 401-584 cm−1. The XRD and SEM characterizations showed that the structure and crystal phase of ZnO were hexagonal wurtzite at dimensions of 36.2 - 45.4 nm. The differences in pH also influenced the dimensions, morphology, and antimicrobial activity. ZnO with pH of 8.0 was characterized by FESEM-EDAX, based on the analysis of morphological uniformity. This characterization obtained rod and cube structures, with atomic ratios of Zn = 61.5% and O = 38.5%. The UV-DRS spectrum showed that the optical band gap was not significantly influenced by the pH of the reactant solution, with a value of Eg = 3.00–3.11 eV. The differences in morphology further distinguished anti-bacterial properties on textile fibres, through the use of the Gram-negative and positive bacteria (Pseudomonas aeruginosa and Staphylococcus aureus), with inhibition zones of 17-21 mm and 21-25 mm, respectively. Therefore, ZnO is classified as a very strong antibacterial material compared to amoxicillin, with an inhibition zone of 13.6 mm.

scholarly journals Enzymic glucosylation of phenols

1967 ◽  
Vol 105 (2) ◽  
pp. 655-662 ◽  
Author(s):  
Shirley M. Hopkinson ◽  
J. B. Pridham
Keyword(s):  
Carboxylic Acid ◽  
Aspergillus Niger ◽  
Deae Cellulose ◽  
Hydroxyl Groups ◽  
Carboxylic Acid Groups ◽  
Alcoholic Hydroxyl

1. A transglucosylase fraction has been obtained from the mycelium of Aspergillus niger. 2. The preparation will transfer α-d-glucopyranosyl residues from maltose and other α-d-glucopyranosides to phenolic and alcoholic hydroxyl groups and to carboxylic acid groups. 3. α-Isomaltosides and α-maltosides are formed when resorcinol and catechol are used as acceptors. 4. pH precipitation and DEAE-cellulose chromatography were used to resolve the activity into two fractions. The properties, in particular polyol inhibition, of one of these fractions have been examined in detail.

scholarly journals Biosynthesis of Zinc Oxide (ZnO) Using Culture Biomass of Aspergillus Niger :The Influence of pH On Textile Morphology And Antimicrobial Activity

2021 ◽  
Author(s):  
Yetria Rilda ◽  
Rifki Rinaldi ◽  
Syukri Syukri ◽  
Armaini Armaini ◽  
Refinel Refinel ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Zinc Oxide ◽  
Aspergillus Niger ◽  
Sol Gel ◽  
Inhibition Zone ◽  
Antibacterial Activities ◽  
Hydroxyl Groups ◽  
Cell Biomass ◽  
A Value ◽  
Size And Morphology

Abstract The biosynthesis of zinc oxide (ZnO) is performed through enzymatic mechanisms, by controlling the particle size and morphology of the compound using the sol-gel method. Furthermore, this method utilizes stabilizer obtained from the cell biomass of Aspergillus niger bacteria, in order to yield homogeneous and consistent products, which corresponds with the XRD outcome that exhibits good crystallinity. The evaluation of functional, morphological, and antibacterial activities was carried out at pH 6.0-13.0, as the prepared samples were characterized by FT-IR. The analysis showed the interaction of hydroxyl groups, aromatic rings, as well as N-H and O-Zn-O compounds at a wavenumber of 401-584 cm−1. The XRD and SEM characterizations showed that the structure and crystal phase of ZnO were hexagonal wurtzite at dimensions of 36.2 - 45.4 nm. The differences in pH also influenced the dimensions, morphology, and antimicrobial activity. ZnO with pH of 8.0 was characterized by FESEM-EDAX, based on the analysis of morphological uniformity. This characterization obtained rod and cube structures, with atomic ratios of Zn = 61.5% and O = 38.5%. The UV-DRS spectrum showed that the optical band gap was not significantly influenced by the pH of the reactant solution, with a value of Eg = 3.00–3.11 eV. The differences in morphology further distinguished anti-bacterial properties on textile fibres, through the use of the Gram-negative and positive bacteria (Pseudomonas aeruginosa and Staphylococcus aureus), with inhibition zones of 17-21 mm and 21-25 mm, respectively. Therefore, ZnO is classified as a very strong antibacterial material compared to amoxicillin, with an inhibition zone of 13.6 mm.

Crystal structure of fungal tannase from Aspergillus niger

2021 ◽  
Vol 77 (2) ◽  
pp. 267-277
Author(s):  
Liangbo Dong ◽  
William J. McKinstry ◽  
Li Pan ◽  
Janet Newman ◽  
Bin Ren
Keyword(s):  
Crystal Structure ◽  
Aspergillus Niger ◽  
Gallic Acid ◽  
Industrial Applications ◽  
Catalytic Triad ◽  
Hydroxyl Groups ◽  
Hydrophobic Contact ◽  
Hydrolase Fold ◽  
Pharmaceutical Industries ◽  
Serine Esterases

Tannases are serine esterases that were first discovered in fungi more than one and half centuries ago. They catalyze the hydrolysis of the gallolyl ester bonds in gallotannins to release gallic acid, which is an important intermediate in the chemical and pharmaceutical industries. Since their discovery, fungal tannases have found wide industrial applications, although there is scarce knowledge about these enzymes at the molecular level, including their catalytic and substrate-binding sites. While this lack of knowledge hinders engineering efforts to modify the enzymes, many tannases have been isolated from various fungal strains in a search for the desired enzymatic properties. Here, the first crystal structure of a fungal tannase, that from Aspergillus niger, is reported. The enzyme possesses a typical α/β-hydrolase-fold domain with a large inserted cap domain, which together form a bowl-shaped hemispherical shape with a surface concavity surrounded by N-linked glycans. Gallic acid is bound at the junction of the two domains within the concavity by forming two hydrogen-bonding networks with neighbouring residues. One is formed around the carboxyl group of the gallic acid and involves residues from the hydrolase-fold domain, including those from the catalytic triad, which consists of Ser206, His485 and Asp439. The other is formed around the three hydroxyl groups of the compound, with the involvement of residues mainly from the cap domain, including Gln238, Gln239, His242 and Ser441. Gallic acid is bound in a sandwich-like mode by forming a hydrophobic contact with Ile442. All of these residues are found to be highly conserved among fungal and yeast tannases.

Fungus ball paranasal sinuses: pattern of histopathology and culture characteristics

2019 ◽  
Vol 49 (20) ◽  
Author(s):  
Nugroho Suharsono
Keyword(s):  
Aspergillus Niger ◽  
Paranasal Sinus ◽  
Paranasal Sinuses ◽  
Histopathological Examination ◽  
Morphological Characteristics ◽  
Sinus Surgery ◽  
Nasal Discharge ◽  
Fungus Ball ◽  
Methenamine Silver ◽  
Fungus Balls

Background: Fungal infection of the nose and paranasal sinuses is an uncommon condition which is now being increasingly recognized. The clinical presentation is not specific with various symptoms such as nasal obstruction, purulent nasal discharge, facial pain, and chronic cough. Only unilaterality may alert the clinician. Purpose: To find the morphological characteristics of the fungus in patients with paranasal sinus fungus ball. Methods: A retrospective study of 13 paranasal sinus fungus balls cases which underwent endoscopic sinus surgery at Department of Otorhinolaryngology Head and Neck Surgery St. Vincentius A Paulo Hospital Surabaya from March, 2012 until December, 2013. Age, sex, histopathology and fungal cultur were analysed. Histopathologic sections of all the patients were stained with hematoxylin and eosin (H&E), and Gomori methenamine silver (GMS). The specimens were then cultured on Sabouraud dextrose agar plates and incubated at 30°C for 1 month. At the end of the incubation period, the samples were evaluated microscopically to detect fungi and identify their species. Results: The age reported of the 13 patients, was ranging from 36 to 63 years old. There was a significant female predominance, 10 female patients (76.92%) and 3 male patients (23.08%). Histopathological examination showed that most causative agents were Aspergillus species 92.31% (12/13). Culture test was positive for 69.23% (9/13). Aspergillus niger (61.54%, 8/13) is the most frequent fungus reported to cause fungus balls. Conclusion: Pattern of histopathologic on HE and GMS is very helpful and sensitive to identify fungi. The most common isolated mould in our study was Aspergillus niger.Keywords: fungus ball, histopathology and culture, Aspergillus nigerABSTRAK Latar Belakang: Infeksi jamur di hidung dan sinus paranasal merupakan kondisi yang jarang terjadi, namun kini lebih sering ditemukan. Gejala klinisnya tidak spesifik dapat berupa obstruksi hidung, sekret dari hidung, nyeri wajah, dan batuk kronis. Bila terjadi unilateral, patut diwaspadai oleh para klinisi. Tujuan: Untuk mengetahui karakteristik morfologi fungus yang didapati pada pasien sinusitis jamur yang kami teliti. Metode: Dilakukan penelitian retrospektif pada 13 pasien sinusitis jamur yang menjalani bedah sinus endoskopi di Departemen Otorinolaringologi-Kepala Leher Rumah Sakit St. Vincentius A Paulo Surabaya dari bulan Maret 2012 sampai dengan Desember 2013. Dilakukan analisis usia, jenis kelamin, histopatologi dan kultur jamur. Pewarnaan preparat histopatologi menggunakan Hematoxylin dan eosin (H&E) dan Gomori Methenamine Silver (GMS). Kemudian spesimen diletakkan pada piring agar Sabouraud dextrose, dan dilakukan inkubasi pada suhu 30°C selama satu bulan. Pada akhir masa inkubasi, sampel dievaluasi dengan mikroskop untuk mendeteksi jamur dan spesiesnya. Hasil: Didapati usia 13 penderita berkisar dari 36-63 tahun. Wanita lebih dominan sebanyak 10 penderita (76,92 %) dan 3 penderita laki-laki (23,08%). Hasil pemeriksaan histopatologi menunjukkan spesies Aspergillus sebagai penyebab utama (92,31%) pada 12 penderita (12/13).Tes kultur positif pada 69,23% (9/13). Jamur yang paling sering menyebabkan bola jamur pada sinus adalah Aspergillus niger (61,54%, 8/13). Kesimpulan: Pewarnaan preparat histopatologi menggunakan Hematoxylin dan eosin (H&E) dan Gomori Methenamine Silver (GMS) sangat berguna dan sensitif dalam mendeteksi adanya jamur. Jenis jamur yang paling banyak ditemukan pada penelitian kami adalah Aspergillus niger.

Bleaching ability of pre-hydrolyzed pulps in the context of a biorefinery mill

TAPPI Journal ◽  
2013 ◽  
Vol 12 (11) ◽  
pp. 49-53 ◽  
Author(s):  
CHRISTINE CHIRAT ◽  
LUCIE BOIRON ◽  
DOMINIQUE LACHENAL
Keyword(s):  
Carbon Content ◽  
Acid Hydrolysis ◽  
13C Nmr ◽  
Kraft Lignin ◽  
Kappa Number ◽  
Hydroxyl Groups ◽  
Kraft Pulps ◽  
Quaternary Carbon ◽  
Oxygen Delignification

Autohydrolysis and acid hydrolysis treatments were applied on mixed softwood chips. The cooking ability was studied by varying the alkali and duration of the cook. Pulps with kappa numbers varying from 30 to 70 were obtained. The bleaching ability of these pulps was studied and compared to control kraft pulps. The prehydrolyzed pulps were shown to be more efficiently delignified by oxygen than the control kraft pulps starting from the same kappa number. Furthermore, the final bleaching was also easier for these pulps. It was also shown that extensive oxygen delignification applied on high-kappa pre-hydrolyzed pulps could be a way to improve the overall yield, which is a prerequisite for the development of such biorefinery concepts. Lignin was isolated from the control kraft and the two pre-hydrolyzed kraft pulps and analyzed by 13C NMR. Lignins from pre-hydrolyzed kraft pulps had similar free phenolic groups content to the control kraft lignin, but their aliphatic hydroxyl groups and β-O-4 content were lower than for the control lignin. The quaternary carbon content was the same for all the samples.

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