sodium-dodecyl-sulfate and acetic-anhydride

An alkalophilic Aspergillus nidulans KK-99 produced an alkaline, thermostable xylanase (40 IU/ml) in a basal medium supplemented with wheat bran (2% w/v) and KNO3 (at 0.15% N) pH 10.0 and 37 degrees C. The partially purified xylanase was optimally active at pH 8.0 and 55 degrees C. The xylanase was stable in a broad pH range of 4.0-9.5 for 1 h at 55 degrees C, retaining more than 80% of its activity. The enzyme exhibited greater binding affinity for xylan from hardwood than from softwood. The xylanase activity was stimulated (+25%) by Na+ and Fe2+ and was strongly inhibited (maximum by 70%) by Tween-20, 40, 60, SDS, acetic anhydride, phenylmethane sulphonyl fluoride, Triton-X-100. The xylanase dose of 1.0 IU/g dry weight pulp gave optimum bleach boosting of Kraft pulp at pH 8.0 and temperature 55 degrees C for 3 h reaction time.

Topics: Acetic Anhydrides; Aspergillus nidulans; Chlorine Compounds; Culture Media; Enzyme Activation; Enzyme Stability; Hydrogen-Ion Concentration; Industrial Microbiology; Industry; Iron; Nitrates; Paper; Photobleaching; Polysorbates; Potassium Compounds; Protease Inhibitors; Sodium; Sodium Dodecyl Sulfate; Streptomyces; Substrate Specificity; Surface-Active Agents; Temperature; Time Factors; Tosyl Compounds; Triticum; Xylan Endo-1,3-beta-Xylosidase; Xylans; Xylosidases