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

Two alpha-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 alpha-arabinofuranosidases were classified on GH51 (alpha-Ara1) and GH54/CBM42 (alpha-Ara2) families. After sugarcane bagasse saccharification, using the commercial cellulase-rich cocktail supplemented with alpha-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 alpha-Ara1 supplementation under the same saccharification conditions. The enzymes presented maximum activity at pH 4.0, and 60 degrees C. Both alpha-Ara1 and alpha-Ara2 were thermostable at 50 degrees C, presenting half-life values of 68 and 77 h, respectively. The enzyme alpha-Ara2 presented higher K-Mapp for synthetic substrate rho NP-alpha-arabinofuranoside (1.38 mmol/L) and wheat arabinoxylan (1.28 mmol/L) when compared with alpha-Ara1. A new fungal alpha-arabinofuranosidase structure, still little described in the GH51 family, was predicted. Furthermore, the results indicated that alpha-Ara2 is a promising molecule to be used to supplement cocktails for lignocellulose degradation.