Two α-Arabinofuranosidases from Chrysoporthe cubensis and Their Effects on Sugarcane Bagasse Saccharification

Two α-arabinofuranosidases from the fungus Chrysoporthe cubensis COAD 3356 were partially purified, identified, characterized, and applied to the sugarcane bagasse saccharification to evaluate the potential of these enzymes to increase the sugar production from lignocellulosic biomass. The α-arabinofuranosidases were classified on GH51 (α-Ara1) and GH54/CBM42 (α-Ara2) families. After sugarcane bagasse saccharification, using the commercial cellulase-rich cocktail supplemented with α-Ara2 (15 U/g), there was an increase of 1.6, 3.9, and 6.1 times in the release of glucose, xylose, and arabinose, respectively. On the other hand, there was no increase in sugar release with α-Ara1 supplementation under the same saccharification conditions. The enzymes presented maximum activity at pH 4.0, and 60 °C. Both α-Ara1 and α-Ara2 were thermostable at 50 °C, presenting half-life values of 68 and 77 h, respectively. The enzyme α-Ara2 presented higher K_Mapp for synthetic substrate ρNP-α-arabinofuranoside (1.38 mmol/L) and wheat arabinoxylan (1.28 mmol/L) when compared with α-Ara1. A new fungal α-arabinofuranosidase structure, still little described in the GH51 family, was predicted. Furthermore, the results indicated that α-Ara2 is a promising molecule to be used to supplement cocktails for lignocellulose degradation.

Graphical Abstract