Production of high-pure xylooligosaccharides from sugarcane bagasse using crude β-xylosidase-free xylanase of Bacillus subtilis KCX006 and their bifidogenic function

Abstract

Xylooligosaccharides (XOS) are used as prebiotics in food industries. XOS with high purity is required for effective prebiotic function. All crude xylanases exhibit β-xylosidase, which forms significant amount of xylose and reduces the yield and purity of XOS. Here, we describe the use of crude xylanase of Bacillus subtilis devoid of β-xylosidase to produce high-pure XOS from ammonia pretreated sugarcane bagasse. MALDI-TOF-MS and HPLC analysis of XOS showed the formation of xylobiose, xylotriose and xylotetraose with xylobiose as the major product. The conversion of bagasse to XOS was >99% with negligible amount of xylose (0.4%). NMR analysis of XOS mixture indicated the presence of arabinosyl and glucuronyl substituted XOS. The relative content of substituted XOS in the mixture was 32%. The XOS mixture supported growth of probiotic bifidobacterial strains under anaerobic conditions. The bifidobacterial strains completely utilized XOS with production of short chain fatty acids indicating their prebiotic function. The concentration of fatty acids formed was in the order of acetate, formate and lactate. Hence, the present method would be useful for further development of low-cost process for production of high-pure prebiotic XOS from lignocellulosic materials.