Product patterns of a feruloyl esterase from Aspergillus nidulans on large feruloyl-arabino-xylo-oligosaccharides from wheat bran

A purified feruloyl esterase (EC 3.1.1.73) from Aspergillus nidulans produced in Pichia pastoris was used to study the de-esterification of large feruloyl oligosaccharides consisting of 4 to 20 pentose residues and (xylose plus arabinose) and one ferulic acid residue. The feruloyl oligosaccharides were prepared from total oligosaccharidic hydrolysates from wheat bran treated with a purified endoxylanase from Thermobacillus xylanilyticus. The feruloyl esterase showed similar specific activity but an affinity about 3.5-fold higher towards feruloyl oligosaccharides than towards methyl ferulate. Mass spectrometry analysis of the products after long-term enzymatic hydrolyses showed that the esterase was able to hydrolyze the largest feruloyl oligosaccharides and therefore could act alone on feruloyled xylans. Consequently, the feruloyl esterase from A. nidulans could be useful for the enzymatic deconstruction of xylans in plant cell walls.