Production and properties of xylanases from Aspergillus terricola Marchal and Aspergillus ochraceus and their use in cellulose pulp bleaching |
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Authors: | M Michelin S C Peixoto-Nogueira J H A Betini T M da Silva J A Jorge H F Terenzi M L T M Polizeli |
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Institution: | 1. Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeir?o Preto, Universidade de S?o Paulo, Ribeir?o Preto, Brazil 2. Departamento de Bioquímica e Imunologia, Faculdade de Medicina de Ribeir?o Preto, Universidade de S?o Paulo, Ribeir?o Preto, Brazil
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Abstract: | Aspergillus terricola and Aspergillus ochraceus, isolated from Brazilian soil, were cultivated in Vogel and Adams media supplemented with 20 different carbon sources, at
30 °C, under static conditions, for 120 and 144 h, respectively. High levels of cellulase-free xylanase were produced in birchwood
or oat spelt xylan-media. Wheat bran was the most favorable agricultural residue for xylanase production. Maximum activity
was obtained at 60 °C and pH 6.5 for A. terricola, and 65 °C and pH 5.0 for A. ochraceus. A. terricola xylanase was stable for 1 h at 60 °C and retained 50% activity after 80 min, while A. ochraceus xylanase presented a t
50 of 10 min. The xylanases were stable in an alkali pH range. Biobleaching of 10 U/g dry cellulose pulp resulted in 14.3% delignification
(A. terricola) and 36.4% (A. ochraceus). The brightness was 2.4–3.4% ISO higher than the control. Analysis in SEM showed defibrillation of the microfibrils. Arabinase
traces and β-xylosidase were detected which might act synergistically with xylanase. |
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