Immobilization of xylanase from Bacillus pumilus strain MK001 and its application in production of xylo-oligosaccharides.

Xylanase from Bacillus pumilus strain MK001 was immobilized on different matrices following varied immobilization methods. Entrapment using gelatin (GE) (40.0%), physical adsorption on chitin (CH) (35.0%), ionic binding with Q-sepharose (Q-S) (45.0%), and covalent binding with HP-20 beads (42.0%) showed the maximum xylanase immobilization efficiency. The optimum pH of immobilized xylanase shifted up to 1.0 unit (pH 7.0) as compared to free enzyme (pH 6.0). The immobilized xylanase exhibited higher pH stability (up to 28.0%) in the alkaline pH range (7.0-10.0) as compared to free enzyme. Optimum temperature of immobilized xylanase was observed to be 8 degrees C higher (68.0 degrees C) than free enzyme (60.0 degrees C). The free xylanase retained 50.0% activity, whereas xylanase immobilized on HP-20, Q-S, CH, and GE retained 68.0, 64.0, 58.0, and 57.0% residual activity, respectively, after 3 h of incubation at 80.0 degrees C. The immobilized xylanase registered marginal increase and decrease in Km and Vmax values, respectively, as compared to free enzyme. The immobilized xylanase retained up to 70.0% of its initial hydrolysis activity after seven enzyme reaction cycles. The immobilized xylanase was found to produce higher levels of high-quality xylo-oligosaccharides from birchwood xylan, indicating its potential in the nutraceutical industry.