Endo-xylanase induced xylooligosaccharide production from corn cobs, its structural features, and concentration-dependent antioxidant activities

Xylooligosaccharides (XOS) are considered as prebiotics, as they help in enhancing the growth of beneficial microbes found in the gut. In the present study, partially purified xylanase fromThermomyces lanuginosusVAPS-24 was used for the production of XOS from xylan extracted from corn cobs. The mild alkali treatment with 20% NaOH yielded 32 +/- 1.8% (w/w) xylan and it was structurally characterized by FTIR. The corn cob xylan (2%w/v), when treated with partially purified 20 U VAPS-24 xylanase for 8 h at 45 degrees C, yielded 6.9 +/- 0.03 mg/ml of XOS. The XOS contained mainly xylobiose (X2) and xylotriose (X3) which were purified and analyzed using(13)C-NMR spectroscopy which showed predominant presence of (1-4) linked beta-d-xylose residues. HPLC analysis showed characteristic peaks of xylotriose, xylobiose, and xylose in the XOS mixture. The produced XOS showed concentration-dependent antioxidant activities and probiotic growth promotion. Further, the genes responsible for the metabolism of XOS in probiotics were identified and their probable interactions and coexpression of genes were studied in silico.