Xylanase Preparation By Aspergillus Niger ATCC16404 Fermentation Of Soybean Hull And Production Of Xylo-oligosaccharides

Components of incubation media and followed optimum conditions for enzyme production were optimized in solid-state fermentation of soybean hull by Aspergillus niger ATCC 16404 to produce xylanase, whose activity was determined by DNS. Results of single factor experiments showed that the optimum components of incubation media contain ammonium sulfate and magnesium sulfate used as nitrogen source and mineral element, with 2% addition based on the weight of 25～50 mesh dry soybean hull, and without additional carbon source and surfactant. Solid-to-liquid ratios, initial pH, incubation time, inoculum size were selected to optimize the condition of enzyme production. The highest xylanase activity obtained by orthogonal experiment and proof test was 366.29 U/g at the optimum fermentation conditions of liquid-to-solid ratiosl.00:1, initial pH 5.5,3 d incubation,0.3 mL/10 g spore suspension of 1.0×10'/mL concentration.Effect of the concentration of NaOH, liquid-to-solid ratios, extraction temperature, extraction time on the extraction of hemicellulose from soybean dietary fiber were studied by optimization of single-factor experiments and response surface. The yield of hemicellulose was 4.55% at the optimum condition of liquid-to-solid ratios16.42:1, extraction time7.65 h, NaOH concentration 4.28%, extraction temperature 45℃.Effect of time, pH, the addition amount of active carbon temperature on decolorization ratio of hemicellulose hydrolysates of xylanase by active carbon and reducing sugar retention rate were studied by single-factor experiments, under which pH, the addition amount of active carbon and temperature was choosed to optimize the decolorization ratio and reducing sugar retention rate designed by response surface using Design-expert7.1.2 software at the basis of decolorization time 50 min and rotate speed 150 r/min. The decolorization ratio and reducing sugar retention rate are 96.91% and 96.52% respective at the relatively optimum condition of reducing sugar retention rate:pH3.85, addition amount of active carbon 1%, temperature 30℃.Cation resin 001×7 and anion resin 201×7 were choosed to associated desalination by static and dynamic desalination of decolorized xylo-oligosaccharides solution by active carbon. Content of xylo-oligosaccharides in the solution is 88.35%, which detected by ion chromatograph.