Abstract
Many fungi are used in order to extract products from their metabolism through bioprocesses capable of minimizing adverse effects caused by agro-industrial wastes in the environment. The aim of this study was to evaluate the xylanase production by an Aspergillus niger strain, using agro- industrial wastes as substrate. Brewer's spent grain was the best inducer of xylanase activity. Higher levels of xylanase were obtained when the fungus was grown in liquid Vogel medium, pH 5.0, at 30oC, during 5 days. The temperature for optimum activity was 50oC and optimum pH 5.0. The enzyme was stable at 50oC, with a half-life of 240 min. High pH stability was verified from pH 4.5 to 7.0. These characteristics exhibited by A. niger xylanase turn this enzyme attractive for some industrial applications, such as in feed and food industries. Additionally, the use of brewer's spent grain, an abundantly available and low-cost residue, as substrate for xylanase production can not only add value and decrease the amount of this waste, but also reduce xylanase production cost.
Highlights
Xylans are the main constituents of hemicellulose, the world’s second most abundant resource after cellulose. This complex heteropolysaccharide consists of a main chain of 1.4 -D-xylose monomers containing different substituents or ramifications
The substituents including arabinofuranosyl, glucuronyl and acetyl groups show a pronounced influence on its chemical and structural properties, and on the enzymatic degradability of xylan in lignocelluloses (COLLINS et al, 2005; KHANDEPARKER et al, 2011; KULKARNI et al, 1999)
Filamentous fungi are widely used as enzyme producers and are generally considered as more potent xylanolytic enzymes producers than bacteria and yeast (KRISANA et al, 2005; POLIZELI et al, 2005)
Summary
Xylans are the main constituents of hemicellulose, the world’s second most abundant resource after cellulose This complex heteropolysaccharide consists of a main chain of 1.4 -D-xylose monomers containing different substituents or ramifications. Biological Sciences xylans hydrolysis, which release long and short xylo-oligosaccharides, or those that only attack longer chains (KHENG; OMAR, 2005). These enzymes have applications in conversion of lignocellulosic substances to chemicals and fuels, animal feed digestion, food and textile industries, and as bleaching agents in the pulp and paper processing (KNOB et al, 2010; MOURE et al, 2006; POLIZELI et al, 2005). Filamentous fungi are widely used as enzyme producers and are generally considered as more potent xylanolytic enzymes producers than bacteria and yeast (KRISANA et al, 2005; POLIZELI et al, 2005)
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