* Corresponding author: monika_sharma540@yahoo.com (Monika Sharma)               1 Department of Biotechnology, Panjab University, Chandigarh, India 2 Department of Microbial Biotechnology, Panjab University, Chandigarh, India ARTICLE INFO ABSTRACT Article History: Received 15 Jan 2014 Accepted 01 Feb 2016 The hemicellulose xylan, is the second most abundant renewable resource in the world. It is the main component of the plant cell walls and has lot of commercial value. Xylans can be degraded by xylanolytic enzymes called xylanases (Endo-1, 4-α-xylanase) and produce xylooligosaccharides, xylobiose and xylose. Xylanases can be obtained from microbes (fungal, bacterial) and plants. Microbial xylanases have gained special attention as they have tremendous potential for various applications. They have been extensively studied for their application in paper and fibre making industry, baking, brewing and juice making industry, feed and non-food (biofuels and soap making) industry. Extensive research on xylanases is further expanding its applicability. The review highlights the structure, classification, purification and industrial applications of different xylanases. It also discusses the methods of improvement of the enzyme production i.e. immobilization, protein engineering and recombinant DNA technology to make it more economical and to suit the commercial applications.           Keywords: Xylan Endo-xylanases Protein purification Xylanase application Recombinant DNA technology Article Type: Full Length Review Article !"# Plant cell walls have three major polymeric constituents: cellulose, hemicellulose and lignin. Hemicelluloses are embedded in the cell walls of plants with pectin. They contain D-pentose sugars mainly and have xylose as its largest component [1]. Xylan, one of the hemicelluloses, is a polymer of xylose and represents more than 20–40% of plant biomass, making it second most abundant polysaccharide in world. Xylans are mainly found in secondary walls of the plant cell wall. This complex molecule is composed of 1,4 linked xylose chains with branches containing arabinose and 4-O-methylgluconic acid [2]. This structure can be degraded by xylanolytic enzymes. 1,4- endoxylanases play a major role in degradation of xylan backbone by catalyzing the random hydrolysis of xylosidic linkages. On the other hand, β- xylosidases release xylosyl residues by endwise attack on xylooligosaccharides in xylan [3]. The abundance of xylan clearly indicates that xylanolytic enzymes can play Journal of Basic and Applied Mycology Volume 12 | Issue I | 2016 ISSN: 0972-7167 (P) ISSN: 2455-3875 (O) Available online at www.sbamjournal.com