Production and characterization of xylanase from a beta-amylolytic strain of Bacillus megaterium

Bacillus megaterium B6 ATCC 51946, a potent beta-amylase producing strain produced extracellular xylanase (EC 3.2.1.8) when cultivated in the presence of xylan as sole carbon source. The strain showed maximum xylanolytic activity after 12 h growth, and was capable of fermenting various agricultural wastes, of which under-utilized jute stalk proved to be best for production of xylanase. The ultrafiltered xylanase showed temperature and pH optima at 85 degrees C and 7.5, respectively. The enzyme was stable at 50 degrees C for 20 min and in the pH range of 7-9. The stability of the enzyme in the presence of thiol inhibitors revealed the absence of thiols at its active site. The enzyme was inactivated in the presence of Hg2+. Absence of substrate cross specificity and high temperature optima of the enzyme made it applicable to pulp and bleaching processes. The high saccharifying potential and ability to hydrolyse lignocellulosic residues favour its application in the commercial production of xylose, a sugar of food and pharmaceutical importance.