Abstract

The present study aimed to evaluate the enzymatic production of XOS, antioxidant activities together with total phenolic contents from different lignocellulosic materials and birchwood xylan using both crude and pure forms of Bacillus amyloliquifaciens NRRL B-14393 xylanase respectively. The mode of action of the pure xylanase was studied by HPLC and the end products analysis of birchwood xylan revealed that xylose, xylobiose and xylotriose were the only end products. The resulted XOS mixture exhibited potent antioxidant activity of 87.36 % and high total phenolic content of 182.88 mg GAE/ liter of extract. XOS were obtained from different alkali pretreated agricultural residues by the crude xylanase action with a yield in a range from 54.4% to 85.5%. Maximum scavenging abilities and total phenolic contents of XOS mixtures of all the tested materials were determined. XOS mixtures of orange and mango peels revealed relatively higher antioxidant activities (96% and 76.84% ,respectively) and total phenolic acid contents (156.32 and 133.74 mg GAE/ liter of extract ,respectively) compared to the other XOS mixtures. In conclusion, Bacillus amyloliquifaciens NRRL B-14393 xylanase could be a promising source for production of XOS with high phenolic contents and antioxidant activities.

Key words: xylanase; xylooligosaccharides; antioxidant; lignocellulosic materials; Bacillus amyloliquifaciens NRRL B-14393