The trifunctional enzyme (XAR-XYN) associating the Thermoanaerobacter ethanolicus xylosidase-arabinosidase (XAR) with the Thermomyces lanuginosus xylanase (XYN) was produced in E coli to study the effect of the physical association of the fusion partners on the enzymatic efficiency. Recombinant XAR, XYN and XAR-XYN were purified to homogeneity and characterized. The optimal pH and temperature of the XAR-XYN were found to be similar to those of the XAR and XYN, except for less temperature optimum of alpha-arabinosidase activity. Its pH and xylanase activity exhibited more stable than those of the XAR and XYN. Finally, the XAR-XYN was tested for degradation of oat spell xylan and wheat bran, the XAR-XYN was found to be more facile than the corresponding free enzyme degradation of wheat bran but provided little or no advantage on purified xylan. Furthermore cooperation within a trifunctional enzyme containing linker SAGSSAAGSGSG between each partner was achieved, leading to a trifunctional enzyme with enhanced enzymatic efficiency on arabinoxylan. (C) 2009 Elsevier Inc. All rights reserved.