An endo-1,5-arabinanase (abnA) encoding gene from Aspergillus niveus was identified, cloned and successfully expressed in Aspergillus nidulans strain A773. Based on amino acid sequence comparison, the 34-kDa enzyme could be assigned to CAZy GH family 43. Characterization of purified recombinant endo-1,5-arabinanase (AbnA) revealed that it is active at a wide pH range (pH 4.0-7.0) and an optimum temperature at 70 °C. The immobilization of the AbnA was performed via covalent binding onto agarose-modified supports: glyoxyl iminodiacetic acid-Ni 2+, glyoxyl amine, glyoxyl (4% and 10%) and cyanogen bromide activated sepharose. The yield of immobilization was similar on glyoxyl amine and glyoxyl (96%), and higher than glyoxyl iminodiacetic acid-Ni 2+ (43%) support. The thermal inactivation of these immobilized preparations showed that the stability of the AbnA immobilized on glyoxyl 4 and 10% was improved by 4.0 and 10.3-fold factor at 70 °C. The half-life of glyoxyl 4% derivative at 60 °C was >48 h (pH 5), 9 h (pH 7) and 88 min (pH 9). The major hydrolysis product of debranched arabinan or arabinopentaose by glyoxyl agarose-immobilized AbnA was arabinobiose. © 2012 Elsevier B.V. All rights reserved.

This work was supported by grants from Fundaçâo de Amparo à Pesquisa do Estado de São Paulo (FAPESP), Conselho de Desenvolvimento Científico e Tecnológico (CNPq) and Banco SANTANDER S.A. This work is part of Doctor Thesis of André Ricardo de Lima Damásio (A.R.L. Damásio is recipient FAPESP Fellowship).RAP received funding from the Department of Energy, awards 06103-OKL and ZDJ-7-77608-01.

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