Hemicellulases, which catalyze the hydrolysis of plant cell polysaccharides, are multi-domain proteins generally containing structurally discrete catalytic and non­catalytic modules [27]. The most important non-catalytic modules consist of carbohydrate binding domains (CBD), which facilitate the targeting of the enzyme to the polysaccharide, interdomain linkers, and dockerin modules. The dockerin modules mediate the binding of the catalytic domain via cohesion-dockerin inter­actions, either to the microbial cell surface or to enzymatic complexes such as the cellulosome [27, 28].

The coordinated action of hemicellulases is necessary to obtain a satisfactory yield of pentose sugars from lignocellulosic as summarized in Fig. 2. Therefore, the development of low-cost and commercial hemicellulases is expected to be a limelight research area for cellulosic ethanol production. Table 2 shows the hemicel- lulase titers from different microorganisms and their mechanistic applications [29].