Substract and temperature effect on xylanase production by aspergillus fumigatus using low cost agricultural wastes

Arthur Filipe Sousa Gomes,Emanuele Giuliani Franciscon,Bruna Silveira Lamanes Dos Santos,Milla Alves Baffi

doi:10.14393/bj-v32n4a2016-32935

Abstract

This study reports the optimization of xylanase production under solid state fermentation (SSF) by a thermotolerant Aspergillus fumigatus strain (SCB4) isolated from sugarcane bagasse piles of Brazilian Cerrado. Different combinations of low-cost agricultural byproducts in SSF were evaluated: sugarcane bagasse and wheat bran (1:1), sugarcane bagasse and corn straw (1:1) and only sugarcane bagasse. The enzyme biosynthesis by SSF was carried out at different temperatures (40, 45, 50 and 55 o C). The maximum levels of xylanase activity were obtained after 24 h at 45 °C using a culture medium containing sugarcane bagasse and wheat bran (1:1). Under optimal conditions, the fungal culture produced 574 U g -1 of xylanase (units/g of dry substrate). The crude enzyme showed optimal activity at 60 °C and pH 4.5. It exhibited thermostability up to 55 °C, wide range of pH stability and tolerance to ethanol, xylose and glucose. The physicochemical properties shown by this enzyme are appropriate for its application in hydrolysis of lignocellulosic residues for ethanol production and other bioproducts.

Highlights

Xylan is the major polysaccharide of hemicelluloses and is the second most abundant polymer in plant cell wall
The filamentous fungus A. fumigatus SCB4 was obtained from the microbial collection of Laboratory of Environmental Microbiology, Uberlandia Federal University (LAMIC, UFU)
Aspergillus fumigatus SCB4 was cultivated under solid state fermentation (SSF) using three types of substrates: a mixture of sugar cane bagasse and wheat bran (SCB/WB, 1:1 w/w); sugar cane bagasse and corn straw (SCB/CS, 1:1 w/w) and only sugar cane bagasse (SCB) (Table 1)

Summary

Introduction

Xylan is the major polysaccharide of hemicelluloses and is the second most abundant polymer in plant cell wall. Xylanases (β-1,4-Dxylan-xylanohydrolase, EC 3.2.1.8) are the key enzymes responsible for the hydrolysis of xylan, providing the availability of cellulose for the action of cellulases and contributing for an increase in the efficiency of the process of biomass degradation (POLIZELI et al, 2005). Xylanases can be used in paper industry, in the improvement of the quality of animal feed, textile and food processing industries and in the transformation of lignocellulosic materials in fermentable sugars for the production of second generation ethanol (NAIR et al, 2010; BAJAJ; ABBASS, 2011; SOUZA et al, 2012).

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