Hydrolysis of wheat flour arabinoxylan, acid-debranched wheat flour arabinoxylan and arabino-xylo-oligosaccharides by β-xylanase, α-L-arabinofuranosidase and β-xylosidase

A range of alpha-L-arabinofuranosyl-(1-4)-beta-D-xylo-oligosaccharides (AXOS) were produced by hydrolysis of wheat flour arabinoxylan (WAX) and acid debranched arabinoxylan (ADWAX), in the presence and absence of an AXH-d3 alpha-L-arabinofuranosidase, by several GH10 and GH11 beta-xylanases. The structures of the oligosaccharides were characterised by GC-MS and NMR and by hydrolysis by a range of alpha-L-arabinofuranosidases and beta-xylosidase. The AXOS were purified and used to characterise the action patterns of the specific alpha-L-arabinofuranosidases. These enzymes, in combination with either Cellvibrio mixtus or Neocallimastix patriciarum beta-xylanase, were used to produce elevated levels of specific AXOS on hydrolysis of WAX, such as 3(2)-alpha-L-Araf-(1-4)-beta-D-xylobiose (A(3)X), 2(3)-alpha-L-Araf-(1-4)-beta-D-xylotriose (A(2)XX), 3(3)-alpha-L-Araf-(1-4)-beta-D-xylotriose (A(3)XX), 2(2)-alpha-L-Araf-(1-4)-beta-D-xylotriose (XA(2)X), 3(2)-alpha-L-Araf (1-4)-beta-D-xylotriose (XA(3)X), 2(3)-alpha-L-Araf-(1-4)-beta-D-xylotetraose (XA(2)XX), 3(3)-alpha-L-Araf-(1-4)-beta-D-xylotetraose (XA(3)XX), 2(3),3(3)-di-alpha-L-Araf-(1-4)-beta-D-xylotriose (A(2+3)XX), 2(3),3(3)-di-alpha-L-Araf-(1-4)-beta-D-xylotetraose (XA(2+3)XX), 2(4),3(4)-di-alpha-L-Araf-(1-4)-beta-D-xylopentaose (XA(2+3)XXX) and 3(3),3(4)-di-alpha-L-Araf-(1-4)-beta-D-xylopentaose (XA(3)A(3)XX), many of which have not previously been produced in sufficient quantities to allow their use as substrates in further enzymic studies. For A(2,3)XX, yields of approximately 16% of the starting material (wheat arabinoxylan) have been achieved. Mixtures of the alpha-L-arabinofuranosidases, with specific action on AXOS, have been combined with beta-xylosidase and beta-xylanase to obtain an optimal mixture for hydrolysis of arabinoxylan to L-arabinose and D-xylose. (C) 2015 Elsevier Ltd. All rights reserved.