Diversity of microbial endo-β-1,4-xylanases

Endo-beta-1,4-xylanases (EC 3.2.1.8, EXs) are the principal xylan-depolymerizing enzymes produced by microorganisms and plants. Extensive studies of EXs in the past two decades, stimulated by their successful application in the pulp and paper and bakery industries, and as animal feed additives, has greatly increased knowledge on their structure and catalytic properties. This work is briefly reviewed in this article. The best known are EXs of glycosyl hydrolase families 10 and 11, however, new types of EXs are emerging. New important findings can be expected from studies of the plant-microbial interactions focusing on xylanase toxicity for plants and the plant xylanase inhibitors.