Sunday, July 24, 2011
Grand Ballroom, 5th fl (Sheraton New Orleans)
In silico analysis of the genome of Fusarium verticillioides, an endophyte and pathogen of maize, revealed several genes with potential use in the hydrolysis of hemicelluloses. We have cloned a gene, FVEG_05677.3, with putative xylosidase and arabinofuranosidase activities. The gene was expressed in E. coli and the enzyme was subsequently purified. The 57 kDa protein has a specific activity for 4-nitrophenyl-β-D-xylopyranoside (4NPX) of 3.3 U/mg and for 4-nitrophenyl-α-L-arabinofuranoside (4NPA) of 0.78 U/mg. The optimum activity with 4NPX is at 60°C and pH 7.0. The optimum activity with 4NPA is at 50°C and pH 6.5. The activity of the enzyme is specific and did not act on substrates 4-nitrophophenyl-β-D-glucopyranoside and 4-nitrophophenyl-β-D-cellobioside. The β-xylosidase produced by F. verticillioides may have industrial application for the hydrolysis of recalcitrant lignocellulosic feedstocks such as corn fiber.