Process optimization and partial purification of a highly catalytic xylanase from high-altitude novel Bacillus altitudinis strain for efficient production of functional prebiotic xylooligosaccharides.

This study reports the production, statistical optimization, partial purification and characterization of a highly efficient xylanase from a high-altitude soil bacterium, Bacillus altitudinis XYL17, for the enzymatic valorization of agrowaste. A two-step optimization approach combining Plackett-Burman Design (PBD) and Response Surface Methodology (RSM) enhanced xylanase production with minimal resource utilization. The partially purified enzyme exhibited optimal activity at 50-55 °C and pH 6.5, and maintained stability over a broad temperature (5-65 °C) and pH (5.0-9.5) range. Substrate specificity analysis revealed efficient hydrolysis of beechwood xylan (BX) and alkali-extracted corncob xylan (CCX) into major xylooligosaccharides (XOS), achieving a combined yield of 48 % for xylobiose and xylotriose per gram of BX. The XOS displayed antioxidant properties through hypochlorous acid (HOCl) reduction and myeloperoxidase (MPO) inhibition, and supported the growth of probiotic strains Lactobacillus acidophilus MTCC 10703 and Limosilactobacillus fermentum MCC 2759. These findings highlight the potential of B. altitudinis XYL17 as a promising source for industrial xylanase production and establish its xylanase as a robust and versatile biocatalyst for the sustainable conversion of xylan-rich biomass into functional biomolecules, with potential applications in the food and nutraceutical industries.