Degradation of different [(glucurono)arabino]xylans by a combination of purified xylan-degrading enzymes

Abstract

The degradation of [({4-O-methyl-}glucurono)arabino]xylans from rice bran, oat spelts, wheat flour, larchwood, and birchwood with two types of endo-(1,4)-β-xylanase (I and III), (1,4)-β-xylosidase, (1,4)-β-d-arabinoxylan arabinofuranohydrolase (AXH), and an acetyl xylan esterase (AE), single and in combinations was investigated. The endo-(1,4)-β-xylanases showed the highest initial release of reducing end-groups on oat spelt xylan, followed successively by larchwood xylan, wheat flour xylan, birchwood xylan and rice bran xylan. The extent of degradation governed by degree and pattern of substitution was highest for oat spelts, followed by wheat flour and larchwood xylan. The extent of hydrolysis for the commercially available birchwood xylan was low, due to the partly insoluble fraction. Rice bran arabinoxylan could only partly be degraded by the combined action of endo-(1,4)-β-xylanase and AXH. The combination of endo-(1,4)-β-xylanase I or III, with (1,4)-β-xylosidase and AXH, or AE, resulted in the highest degree of hydrolysis after 24 h of incubation.