Production, purification, and characterization of a major Penicillium glabrum xylanase using Brewer's spent grain as substrate.

Adriana Knob,Susan Michelz Beitel,Diana Fortkamp,César Rafael Fanchini Terrasan,Alex Fernando De Almeida

doi:10.1155/2013/728735

Abstract

In recent decades, xylanases have been used in many processing industries. This study describes the xylanase production by Penicillium glabrum using brewer's spent grain as substrate. Additionally, this is the first work that reports the purification and characterization of a xylanase using this agroindustrial waste. Optimal production was obtained when P. glabrum was grown in liquid medium in pH 5.5, at 25 °C, under stationary condition for six days. The xylanase from P. glabrum was purified to homogeneity by a rapid and inexpensive procedure, using ammonium sulfate fractionation and molecular exclusion chromatography. SDS-PAGE analysis revealed one band with estimated molecular mass of 18.36 kDa. The optimum activity was observed at 60 °C, in pH 3.0. The enzyme was very stable at 50 °C, and high pH stability was verified from pH 2.5 to 5.0. The ion Mn2+ and the reducing agents β-mercaptoethanol and DTT enhanced xylanase activity, while the ions Hg2+, Zn2+, and Cu2+ as well as the detergent SDS were strong inhibitors of the enzyme. The use of brewer's spent grain as substrate for xylanase production cannot only add value and decrease the amount of this waste but also reduce the xylanase production cost.

Highlights

Xylan is a major structural polysaccharide of plant-cell walls being the second most prevalent in nature after cellulose
Highest values of xylanase activity were obtained with oat spelt xylan, corresponding to 25.44 U/mL and 64.96 U/mg protein
Higher levels of xylanolytic enzymes can be achieved with substrates derived from xylan

Summary

Introduction

Xylan is a major structural polysaccharide of plant-cell walls being the second most prevalent in nature after cellulose. It is a heterogeneous polymer constituted primarily by a linear β-(1,4)-D-xylose backbone, which is partially acetylated and substituted at different degrees by a variety of side chains, mainly α-D-glucuronosyl and α-L-arabinosyl units. The key enzyme in this process is endo-β-(1,4)-xylanase (EC 3.2.1.8), which cleaves the xylan backbone to xylooligosaccharides [1, 2]. Xylanolytic enzymes have applications in conversion of lignocellulosic materials to chemicals and fuels, animal feed digestion, food and textile industries, and as bleaching agents in the pulp and paper processing [3, 4]

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