Sunday, April 29, 2007

Development and design of enzyme cocktails for extraction of xylose and arabinose from lignocellulosic substrates

Frank Haagensen1, Don Higgins1, and Kevin S. Wenger2. (1) Fuel Research & Development, Novozymes North America, 77 Perry Chapel Church Road, Franklinton, NC 27525, (2) Bioprocess Research, Mascoma Corporation, 16 Cavendish Court Suite 2A, Lebanon, NH 03766


Extraction of carbohydrate monomers from hemicellulose either by partial or complete enzymatic hydrolysis has recently attracted much attention due to the increased focus on biomass conversion for various applications. Arabinose and xylose are the predominant sugar monomers comprising hemicellulose of corn fiber, corn stover and cereal straws. In order to optimize the production yields from conversion of these substrates into ethanol or other products, both cellulose and hemicellulose need to be efficiently hydrolyzed into monomers.


Hydrolysis of arabinoxylan requires at least 2 types of enzymatic functions: (a) side chain-cleaving enzymes, and (b) de-polymerizing enzymes. The significant enzyme activities involved in hemicellulose side chain cleavage are a-L-arabinofuranosidase, a-glucoronidases, ferulic acid esterase, and potentially acetyl esterases, whereas the key functions required for de-polymerizing the xylan backbone are        endo- and exo-xylanases, and b-xylosidase (Numan and Bhosle, 2006). Previous work  has demonstrated the potential of utilizing enzymes for hydrolysis of both water-soluble and insoluble wheat hemicellulose into monomeric sugars by synergistic enzyme activities (Bartolome et al., 1995; de Vries et al., 2000; Sorensen et al., 2003). Mixtures of commercial enzymes with cellulolytic and hemicellulytic activities have been demonstrated to work synergistically providing the necessary enzymatic activities for hydrolysis of soluble wheat arabinoxylans (Sorensen et al., 2005).


The poster will present some of the key elements applied in the development and design of enzyme cocktails for extraction of arabinose and xylose from various types of pre-treated lignocellulosic materials. *