Insight into microbial hemicellulases other than xylanases: a review

Hemicellulases responsible for depolymerization of hemicellulose, including -glucuronidase, -arabinofuranosidase, arabinase, endo-mannanase, -mannosidase, acetyl xylan esterase and feruloyl xylan esterase, were reviewed. They usually exist as multimers with a modified (/)8 Tim barrel fold. In a few cases they possess a substrate binding domain which helps them bind to the substrates bringing efficient hydrolysis. Post-translational modifications are the major reasons leading to enzyme multiplicities to adapt the heterogeneous nature of hemicellulose. Glycosylation is one of the most important post translational modifications and contributes multiple functions to the protein such as stability, multiplicity and in a few cases enzyme activity. Advances in recombinant DNA technology have made it feasible to clone, improve and functionally express them in various hosts. Hemicellulases are traditionally applied in food, feed, detergent and paper industries, but their applications in hydrolysis of hemicellulose to release sugars is expected to increase, driven by the rapid development of lignocellulose biorefineries. Screening more powerful hemicellulases from nature, mining their coding genes from various sources and engineering them genetically are recommended for broadening their applications. (c) 2012 Society of Chemical Industry