Document Type : Original Article
Authors
1
1Department of Chemistry of Natural and Microbial Products, Pharmaceutical and Drug Industries research institute, National Research Centre, El Bohouth Street, Dokki, Giza 12622, Egypt
2
Chemistry of Natural and Microbial Products Department, National Research Centre, 33 El Bohouth st.(former El Tahrir st.), P.O 12622, Dokki, Giza, Egypt.
3
Department of Chemistry of Natural and Microbial Products, Pharmaceutical and Drug Industries research institute, National Research Centre, El Bohouth Street, Dokki, Giza 12622, Egypt
4
Department of Chemistry of Natural and Microbial Products, Division of Pharmaceutical and Drug Industries, National Research Centre, Cairo, Egypt.
Abstract
Conversion of lignocellulosic biomasses into value-added commodities relies on the depolymerization of their constitutive components. Herein, submerged fermentation of rice straw using Trichoderma asperellum AW2 was initially carried out with the production of xylanase activity of 96.638 U/mL. The produced xylanase was characterized in which the highest enzymatic activity was estimated at 50 °C, in the working pH range 5-6 using beech wood xylan concentration of 17.5 mg/mL, with half-life time of 86.6 min at this temperature. In addition, it was an endo-acting enzyme with the capability for releasing xylooligosaccharides. The applicability of the produced xylanase in the hydrolysis of untreated rice straw was evaluated. The result estimated the releasing of 19.9 mg/g of reducing sugars after 8 h that was improved by about 70% by microwave pre-treatment of rice straw with the releasing of mono-sugars in addition to xylooligosaccharides of different degrees of polymerization as it confirmed with the aid of thin layer and high-performance liquid chromatographic analysis. Moreover, the scanning electron microscopy of the waste residue confirmed the potency of the produced xylanase for depolymerizing the hemicellulosic fraction of rice straw. Finally, the antioxidant and the Fibrinolytic activity of the hydrolyzate were estimated in comparison to xylan hydrolyzate.
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