Separation and identification of endoxylanases from Bacillus subtilis and their actions on wheat bran insoluble dietary fibre

A novel and convenient method based on native polyacrylamide gel electrophoresis (PAGE) and homogenization extraction was used for the purification of xylanase from crude enzymes. Two xylanases were purified by this method from the crude enzyme preparation from the selected strain of Bacillus subtilis. Subsequent analysis with thin layer chromatography and high pressure liquid chromatography (HPLC) indicated that these two xylanases were endo-acting enzymes, designated xyl I and xyl II. Both enzymes showed their activities in the pH range from 5.0 to 9.0 at 50 °C and had similar optimum activities at pH 7.0 and at 50 °C. Mn2+ ions enhanced their xylanolytic activities to 2.7-fold whereas Fe3+ completely inhibited them. The action of endoxylanase xyl II on wheat bran insoluble dietary fibre was also studied. The hydrolysis products were shown to contain feruloyl oligosaccharides by paper chromatography.