Screening of Xylanolytic Aspergillus fumigatus for Prebiotic Xylooligosaccharide Production Using Bagasse.

Ana Flavia Azevedo Carvalho,Bruna Escaramboni,Galucia Maria Pastore,Paula Zaghetto De Almeida,Juliana Bueno Da Silva,Pedro De Oliva Neto

doi:10.17113/ftb.53.04.15.4160

Ana Flavia Azevedo Carvalho, Bruna Escaramboni + Show 4 more

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https://doi.org/10.17113/ftb.53.04.15.4160

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Abstract

Sugarcane bagasse is an important lignocellulosic material studied for the production of xylooligosaccharides (XOS). Some XOS are considered soluble dietary fibre, with low caloric value and prebiotic effect, but they are expensive and not easily available. In a screening of 138 fungi, only nine were shortlisted, and just Aspergillus fumigatus M51 (35.6 U/mL) and A. fumigatus U2370 (28.5 U/mL) were selected as the most significant producers of xylanases. These fungi had low β-xylosidase activity, which is desirable for the production of XOS. The xylanases from Trichoderma reesei CCT 2768, A. fumigatus M51 and A. fumigatus U2370 gave a significantly higher XOS yield, 11.9, 14.7 and 7.9% respectively, in a 3-hour reaction with hemicellulose from sugarcane bagasse. These enzymes are relatively thermostable at 40-50 °C and can be used in a wide range of pH values. Furthermore, these xylanases produced more prebiotic XOS (xylobiose and xylotriose) when compared with a commercial xylanase. The xylanases from A. fumigatus M51 reached a high level of XOS production (37.6%) in 48-72 h using hemicellulose extracted from sugarcane bagasse. This yield represents 68.8 kg of prebiotic XOS per metric tonne of cane bagasse. In addition, in a biorefinery, after hemicellulose extraction for XOS production, the residual cellulose could be used for the production of second-generation ethanol.

Highlights

Lignocellulosic waste is a topic of global studies, given that fossil fuel reserves are diminishing, the new agricultural frontiers are limited and the demand for food and biofuels is increasing by the growing world population [1]
The xylanases from A. fumigatus M51 reached a high level of XOS production (37.6 %) in 48–72 h using hemicellulose extracted from sugarcane bagasse
Xylanases were produced by submerged fermentation (SmF) in Erlenmeyer flasks (250 mL) containing 50 mL of medium composed of sugarcane bagasse 3.0 % and: (NH4)2SO4 0.2, MgSO4·7H2O 0.01, K2HPO4 0.1, KH2PO4 0.1, yeast extract 0.5 and micronutrient solution 0.1

Summary

Introduction

Lignocellulosic waste is a topic of global studies, given that fossil fuel reserves are diminishing, the new agricultural frontiers are limited and the demand for food and biofuels is increasing by the growing world population [1]. The addition of XOS to food has excellent physiological effects on the organism, including improvement of bowel function, calcium absorption, prevention of dental caries, protection against cardiovascular disease and reduction of colon cancer risks due to the formation of smaller chain fatty acids [8,9]. They contribute to beneficial effects related to skin and blood, immunological action, antioxidant activities, anti-inflammatory and antiallergenic effects [1,10]

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