Maximum Xylooligosaccharides Yield Research Articles

Co-production of xylanase and xylooligosaccharides from lignocellulosic agricultural wastes

Lignocellulosic biomass including agricultural residues and by-products, and woody biomass are produced worldwide in large amounts every year. With the exception of limited-usage areas, these materials are regarded as waste. Therefore, renewable lignocellulosic biomass is gaining considerable attention because of its potential for use in the production of biofuels and other value-added products. In this study, the co-production of two value-added products, xylanase (enzyme) and xylooligosaccharides (XO), was investigated by utilizing lignocellulosic biomass residues within a multi-product biorefinery framework. Box–Behnken design-based response surface methodology was employed to optimize culture parameters for xylanase production from a thermophilic fungus, Scytalidium thermophilum, and the enzyme was biochemically characterized. Optimized media conditions resulted in an approximately 2-fold increase in xylanase activity compared to the initial conditions. Crude enzyme solution was capable of producing XO from the hemicellulosic fraction of various biomass residues. The highest hemicellulose extraction yield was achieved from corn cob (37.7 ± 1.5%), followed by wheat bran (26.6 ± 0.8%) and cotton stalks (22.2 ± 0.6%). The highest reducing end concentration was obtained from sunflower seed shell (4.89 ± 0.02 mg mL−1), followed by sunflower stalks (4.41 ± 0.03 mg mL−1) and corn cob (3.49 ± 0.09 mg mL−1). Accordingly, corn cob yielded the highest XO production (172.1 mg XO per g raw biomass residue) with the main products of xylose (X1) and xylobiose (X2). In terms of the hemicellulosic fraction, beechwood had the maximum XO yield with 793 mg XO per g hemicellulose. Sunflower seed shell hydrolysis yielded mainly X1 and xylotetrose (X4) without X2 and xylotriose (X3). After 1 h of reaction time, X2 and higher sugars were obtained from the commercial beechwood xylan, while only X1 and X4 were obtained after 6 h. Xylose-free xylobiose was obtained from sugar beet bagasse and wheat bran, which are regarded as potential XO sources because XO with degrees of polymerization from 2–4 are preferred in food applications and XO without xylose are important in the food industry from a prebiotic point of view.

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 29.9kDa. Optimum temperature and pH for xylanase activity of purified xylanase were found to be 50°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°C after 180min. Kinetic parameters like Km and Vmax were found to be 4mg/ml and 7288μmol/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 β-xylosidase free xylanase. Maximum yield of XOS was 7.28±0.14mg/ml and 4.52±0.21mg/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.

Production of xylooligosaccharides from corncob xylan by fungal xylanase and their utilization by probiotics

The selective production of xylooligosaccharides (XOS) was carried out using partially purified xylanase from Aspergillus foetidus MTCC 4898. Corncob xylan was extracted using a mild alkali treatment which yielded 178.73±5.8gofxylan/kg of corncobs. Partially purified β-xylosidase free xylanase was found efficient in releasing xylooligosaccharides from corncob xylan. Maximum yield of xylooligosaccharides was 6.73±0.23mg/ml after 8h of reaction time using 20U of xylanase at 45°C. Purification of XOS was done using activated charcoal column chromatography. The purified XOS preparation contained mainly xylobiose and xylotriose. XOS mixture was found 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 viz. Bifidobacterium adolescentis, Bifidobacterium bifidum, Lactobacillus fermentum, Lactobacillus acidophilus. The results of this study revealed better growth of Bifidobacterium spp. on XOS than Lactobacillus spp.