Characterization of purified fungal endoxylanase and its application for production of value added food ingredient from agroresidues

Xylanase from Aspergillus foetidus MTCC 4898 was purified using ammonium sulphate fractionation followed by ion exchange and gel permeation chromatography with 12.26-fold purity and 29.9% recovery. Purified xylanase was found to be 29.9 kDa. Optimum temperature and pH for xylanase activity of purified xylanase were found to be 50 degrees C and 5.3 respectively. Presence of additives like polyethylene glycol, sodium azide, Tween 80, KCl and NaCl increased the stability of purified xylanase by 35, 29, 28, 32 and 43% respectively at 50 degrees C after 180 min. Kinetic parameters like K-m and V-max, were found to be 4 mg/ml and 7288 mu mol/mg/min respectively. The purified xylanase was found to be an endoxylanase as it produced only xylooligosaccharides (XOS) from birchwood xylan. Production of XOS was carried out from xylan extracted from agro-residues using beta-xylosidase free xylanase. Maximum yield of XOS was 7.28 +/- 1 0.14 mg/ml and 4.52 +/- 0.21 mg/ml from wheat straw xylan and rice straw xylan respectively. XOS mixture was suitable for food industry looking at its high thermal stability at low pH. Prebiotic effect of XOS was evaluated by in vitro fermentation of XOS using known probiotic strains of Bifidobacterium spp. (C) 2013 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.