Purification and Characterization of a New Thermoalkali-Stable xylanase Produced from Bacillus Amyloliquifaciens NRRL B-14393 by Solid-State Fermentation of Water Hyacinth.

Purification and characterization of crude xylanase produced by Bacillus amyloliquifaciens NRRL B-14393 grown on water hyacinth under solid-state fermentation were investigated. Xylanase was purified using DEAE-Sepharose and Sephadex G-100 columns which affected specific activity (1009.14 U/mg) and 18.67 purification fold. The pure xylanase has molecular weights of 34.679 and 29 KDa by gel filtration and SDS-polyacrylamide electrophoresis, respectively. The pure xylanase showed a maximal activity at pH 9.5 and 50 degrees C. The enzyme showed a broad range of pH stability (pH 5.5-12). Xylanase retained its full activity up to 40 degrees C for 15 min. It was stable up to 60 degrees C with a thermal denaturing half-life of 90 min. The enzyme exhibited a high specificity for the birch wood xylan substrate. Xylanase had a Km value of 2.94mg ml(-1) and V-max of 10.92 mu mole min(-1) ml(-1). The enzyme was nearly completely inhibited by MnSO4 and HgCl2 at 1 and 10mM concentration. It consisted of 17 amino acids and rich in aspartic acid and tyrosine. These properties make this enzyme a potential candidate for future use in biotechnological applications particularly in the pulp and paper industry as well as large scale production of xylooligosaccharides.