Xylanolytic Enzymes from Fungi and Bacteria

Abstract

The development of new analytical techniques and the commercial availability of new substrates have led to the purification and characterization of a large number of xylan-degrading enzymes. Furthermore, the introduction of recombinant DNA technology has resulted in the selection of xylanolytic enzymes that are more suitable for industrial applications. For a successful integration of xylanases in industrial processes, a detailed understanding of the mechanism of enzyme action is, however, required. This review gives an overview of various xylanolytic enzyme systems from bacteria and fungi that have been described recently in more detail.

Catalytic role of conserved HQGE motif in the CE6 carbohydrate esterase family

“…Xylan of hemicellulosic polysaccharide plant cell walls is predominantly a 1,4-b-D Dxylose polymer and is commonly substituted to various degrees with arabinosyl and glucuronyl residues and up to 60-70% with acetyl groups [1,2]. Along with a number of fibrolytic enzymes, acetylxylan esterases (AXEs) (EC 3.1.1.72) are important enzymes influencing the digestibility of plant cell-wall material by cleaving the ester bonds and thus removing the acetyl moieties from complex carbohydrates [3][4][5]. A number of AXEs from various organisms, including prokaryotic and eukaryotic cell organisms have been purified and characterized (see Supplementary references).…”

Wood production, wood technology, and biotechnological impacts

“…Oligosaccharides resulting from xylan degradation by endoxylanases are effectively hydrolysed to xylose, the component Katapodis 2006). Such enzymes are therefore necessary for the complete degradation and microbial utilisation of xylan (Sunna & Antranikian 1997, Saha 2003. Besides, the removal of oligosaccharides by xylosidases affects also endoxylanases by preventing the feedback inhibition exerted on these enzymes by their oligosaccharide products .…”

“…Likewise, species of these clades are also prominent producers of cellulases ; see Chapter 19 of this book). In addition, the spectrum of enzymes provided by fungi is further expanded by enzymes with cellulolytic and hemicellulolytic activities that are obtained from bacteria (for a selection of recent reviews on production and applications of the various enzymes see Sunna & Antranikian 1997, Cavaco-Paulo 1998, Bhat 2000, Saha 2000, Śušla & Svobodová 2006Schäfer et al 2007, and also Chapter 19 of this book).…”

“…Xylanases are predominantly produced by micro-organisms (Table 3), but are also found in marine algae, protozoans, crustaceans, insects, snails, and seeds of land plants (Sunna & Antranikian 1997). As in the case of cellulases, microbial production of xylanases can take place in SmF and SSF (see Table 3), although about 80-90% of the commercial xylanases are gained through submerged fermen- Enzyme Production 481 tation, usually with filamentous ascomycetes and their related anamorphic genera , Chávez et al 2006; Table 3).…”

Xylanases of Microorganisms

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