Volume 53, Issue No. 4 Hits: 6475

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Screening of Xylanolytic Aspergillus fumigatus for Prebiotic Xylooligosaccharide Production Using Bagasse

Ana Flavia Azevedo Carvalho1,2*, Pedro de Oliva Neto2, Paula Zaghetto de Almeida2, Juliana Bueno da Silva1, Bruna Escaramboni2 and Glaucia Maria Pastore1


1Department of Food Science, School of Food Engineering, State University of Campinas (UNICAMP), Rua Monteiro Lobato 80, 13083-862 Campinas, SP, Brazil
2Department of Biological Sciences, School of Science and Letters, São Paulo State University (UNESP), Rua Dom Antonio 2100, 19806-380  Assis, SP, Brazil




Article history:
Received March 8, 2015
Accepted June 12, 2015




Key words: 
lignocellulosic materials, xylooligosaccharides, xylanases, bagasse




Summary:
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.





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