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 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 K-m and V-max 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.