IMPROVING BIOCHEMICAL PROCESSES FOR THE PRODUCTION OF SUSTAINABLE FUELS AND CHEMICALS
Location: Renewable Product Technology Research Unit
Title: Purification and characterization of arabinofuranosidase from the corn endophyte Acremonium zeae
Submitted to: Biotechnology Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 27, 2011
Publication Date: June 14, 2011
Citation: Bischoff, K.M., De Rezende, S.T., Larson, T.M., Liu, S., Hughes, S.R., Rich, J.O. 2011. Purification and characterization of arabinofuranosidase from the corn endophyte Acremonium zeae. Biotechnology Letters. 33(10):2013-2018. DOI: 10.1007/s10529-011-0658-9.
Interpretive Summary: In this research we discovered two enzymes that are involved in releasing sugar from lignocellulosic biomass. New enzymes that can degrade cellulose and hemicellulose are needed to help overcome some of the technical barriers to using agricultural residues as feedstocks for fuel ethanol production. Acremonium zeae is a fungus that was found to produce two forms of an arabinofuranosidase enzyme. A mixture of both forms of the enzyme could release high percentages of the sugars arabinose and xylose from corn fiber and wheat hemicellulose. Results will be valuable to researchers developing new enzymes to serve as biocatalysts in the conversion of agricultural residues to fermentable sugars.
Acremonium zeae, one of the most prevalent fungal colonists of preharvest corn, possesses a suite of hemicellulolytic activities including xylanase, xylosidase, and arabinofuranosidase. In the present study, two enzymes with arabinofuranosidase activity were purified from cell-free culture supernatants of A. zeae grown on oat spelt xylan. A 47 kDa enzyme (AF47) was optimally active at 37°C and pH 6.0, and had a specific activity for 4-nitrophenyl-alpha-L-arabinofuranoside (4NPA) of 6.2 U/mg. A 30 kDa enzyme (AF30) was optimally active at 50°C and pH 4.5, and had a specific activity for 4NPA of 12.4 U/mg. AF47 was capable of hydrolyzing 4-nitrophenyl-beta-D-xylopyranoside, 4-nitrophenyl-beta-D-glucopyranoside, and 4-nitrophenyl-beta-D-cellobioside, as well as producing reducing sugar from corn fiber, wheat, and oat spelt arabinoxylan. AF30 had little detectable activity on the 4-nitrophenyl substrates, except for 4NPA, but activity on arabinoxylans from corn fiber, wheat, and oat spelt was at least 7-fold higher than AF47, with specific activities of 109, 358, and 153 U/mg, respectively. A combination of the two enzymes released 61% and 88% of the total arabinose from corn fiber and wheat arabinoxylans. The arabinofuranosidases produced by A. zeae may have industrial application for the enzymatic hydrolysis of recalcitrant lignocellulosic feedstocks such as corn fiber and wheat straw.