Hemicellulases in lignocellulose biotechnology: recent patents

Hemicelluloses comprise a major part of renewable plant biomass and therefore have received considerable attention in lignocellulose biotechnology. Hemicelluloses are a heterogeneous group of structural polysaccharides such as xylan, mannan and arabinan named after their major constituent monomeric sugar. Bioconversion of hemicelluloses proceeds through hydrolysis using hemicellulases. A variety of hemicellulases have been identified from mesophilic and thermophilic microorganisms. First prominent industrial application of a hemicellulase was in the area of pulp biobleaching when xylanases were found to be able to reduce use of toxic chlorine oxide. Later many applications of hemicellulases in various areas such as deinking of paper waste, clarification of fruit juices, upgradation of feed, fodder and fibres, and saccharification were revealed. The present review presents an overview of patents related to hemicellulases including xylanases, mannanases, arabionosidases, acetylxylan esterases (AXE) and other accessory enzymes.