The bread-making functionalities of two Aspergillus niger endoxylanases are strongly dictated by their inhibitor sensitivities

• Published in: Enzyme and microbial technology Vol. 36; no. 4; pp. 417 - 425
• Main Authors: Gebruers, Kurt, Courtin, Christophe M., Moers, Karolien, Noots, Iris, Trogh, Isabel, Delcour, Jan A.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 02-03-2005; Elsevier Science
• Subjects: Aspergillus niger; Biological and medical sciences; Biotechnology; Bread-making; Cereal and baking product industries; Endoxylanase; Endoxylanase inhibitor; Food industries; Functionality; Fundamental and applied biological sciences. Psychology; Triticum aestivum; MM; Endoxylanase inhibitor; Bread-making; SSF; WEAX; EU; Functionality; HPSEC; Aspergillus niger; AX; Endoxylanase; TAXI; WUAX; XIP; Bread making; Enzyme; Endo-1,4-β-xylanase; Fungi; Sensitivity; Glycosidases; Hydrolases; Inhibitor; Fungi Imperfecti; O-Glycosidases; Thallophyta
• ISSN: 0141-0229; 1879-0909
• DOI: 10.1016/j.enzmictec.2004.04.023

A recent approach based on affinity chromatography with immobilised endoxylanase inhibitors was used to isolate two endoxylanases (EC 3.2.1.8) with different bread-making functionalities from an
Aspergillus niger fermentation broth. TAXI (
Triticum aestivum endoxylanase inhibitor) affinity chromatography yielded a TAXI- and XIP (endoxylanase inhibiting protein)-sensitive family 11 endoxylanase (24
kDa, p
I 3.5), XIP affinity chromatography subsequently yielded a family 10 endoxylanase (36
kDa), only inhibited by XIP. While the first enzyme improves bread volume, the latter enzyme has no effect on bread quality whatsoever. The bread-making positive endoxylanase rather selectively hydrolyses water-unextractable arabinoxylan in an in vitro screening method, still performs/is active during bread-making and produces soluble arabinoxylan of high (>11.2
×
10
4
Da) and low molecular mass (≤11.2
×
10
4
Da). In contrast, the bread-making neutral endoxylanase in the in vitro assay displays a bias for water-extractable arabinoxylan and is immediately and almost completely inhibited during the early stages of bread-making. The results show that the functionalities of the purified
A. niger endoxylanases in wheat bread-making are strongly dictated by their sensitivities towards wheat endoxylanase inhibitors.