Production and properties of xylanases from Aspergillus terricola Marchal and Aspergillus ochraceus and their use in cellulose pulp bleaching

• Published in: Bioprocess and biosystems engineering 2010-09, Vol.33 (7), p.813-821
• Main Authors: Michelin, M, Peixoto-Nogueira, S. C, Betini, J. H. A, da Silva, T. M, Jorge, J. A, Terenzi, H. F, Polizeli, M. L. T. M
• Format: Article
• Language: English
• Subjects: Aspergillus; Aspergillus ochraceus; Aspergillus ochraceus - classification; Aspergillus ochraceus - enzymology; Aspergillus terricola; biobleaching; Biological and medical sciences; Biotechnology; Bleaching; Carbon sources; Cellulose; Cellulose - metabolism; Cellulose pulp; Chemistry; Chemistry and Materials Science; Crop residues; Endo-1,4-beta Xylanases - chemistry; Endo-1,4-beta Xylanases - isolation & purification; Endo-1,4-beta Xylanases - metabolism; Environmental Engineering/Biotechnology; Enzyme Activation; Enzyme Stability; Enzymes; Food Science; Fundamental and applied biological sciences. Psychology; Industrial and Production Engineering; Industrial Chemistry/Chemical Engineering; Mold; Original Paper; Pulpwood; scanning electron microscopy; Species Specificity; thermal stability; Triticum aestivum; Wheat bran; Wood - chemistry; Xylanase
• ISSN: 1615-7591; 1615-7605
• DOI: 10.1007/s00449-009-0403-0

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.