Homologue expression of a β-xylosidase from native Aspergillus niger

Abstract

Xylan constitutes the second most abundant source of renewable organic carbon on earth and is located in the cell walls of hardwood and softwood plants in the form of hemicellulose. Based on its availability, there is a growing interest in production of xylanolytic enzymes for industrial applications. β-1,4-xylan xylosidase (EC 3.2.1.37) hydrolyses from the nonreducing end of xylooligosaccharides arising from endo-1,4-β-xylanase activity. This work reports the partial characterization of a purified β-xylosidase from the native strain Aspergillus niger GS1 expressed by means of a fungal system. A gene encoding β-xylosidase, xlnD, was successfully cloned from a native A. niger GS1 strain. The recombinant enzyme was expressed in A. niger AB4.1 under control of A. nidulans gpdA promoter and trpC terminator. β-xylosidase was purified by affinity chromatography, with an apparent molecular weight of 90 kDa, and showed a maximum activity of 4,280 U mg protein(-1) at 70°C, pH 3.6. Half-life was 74 min at 70°C, activation energy was 58.9 kJ mol(-1), and at 50°C optimum stability was shown at pH 4.0-5.0. β-xylosidase kept residual activity >83% in the presence of dithiothreitol (DTT), β-mercaptoethanol, sodium dodecyl sulfate (SDS), ethylenediaminetetraacetate (EDTA), and Zn(2+). Production of a hemicellulolytic free xylosidase showed some advantages in applications, such as animal feed, enzymatic synthesis, and the fruit-juice industry where the presence of certain compounds, high temperatures, and acid media is unavoidable in the juice-making process.

Characterization of the Highly Efficient Acid-Stable Xylanase and β-Xylosidase System from the Fungus Byssochlamys spectabilis ATHUM 8891 (Paecilomyces variotii ATHUM 8891)

“…Intriguingly, PvXyd3A stands out for its thermal properties; the enzyme was demonstrated to be the most thermophilic among Thermoascaceae-derived β-xylosidases (Table 4) and was superior to most fungal and also to several bacterial thermophilic β-xylosidases [37]. To our knowledge, similar thermal characteristics have only been reported for three other GH3 β-xylosidases: those isolated from Aspergillus japonicus MU-2 [40], Aspergillus niger GS1 [38] and Aspergillus ochraceus [41].…”

“…The obtained specific activity for PvXyd3A was also the highest reported among β-xylosidases isolated from Thermoascaceae members (Table 4), as well as being among the highest observed for fungal β-xylosidases in general [37]. Higher specific activity values have only been reported for the wild-type enzymes of Aspergillus niger GS1 [38] and Penicillium janczewskii CRM 1348 [39].…”

Cloning, expression and characterization of β-xylosidase from Aspergillus niger ASKU28

“…from Aspergillus awamori [9], A. japonicus [5], A. nidulans [10], A. niger [11][12][13][14], A. oryzae [15], and Talaromyces emersonii [16] have been cloned and characterized. However, only few studies have characterized their enzymatic properties in complete details [17].…”