Hydrolytic xylanases production from fungi—An assessment for their production, properties and computational analysis of their gene sequences

Abstract Xylanase is the xylan-degrading enzyme which cleaves the β-1,4 backbone of the complex plant cell wall polysaccharide xylan. A xylanolytic enzyme is a group of enzymes involved in the production of xylose, the primary carbon source for cell metabolism. Xylanase is produced by plenty of organisms, but the microbial xylanases are preferable over others because these xylanases are capable of catalyzing the hydrolysis of xylan under mild conditions of the reaction. This widespread group of enzymes produced by fungi with alkaliphilic and thermophilic properties is preferred and important due to its use in paper industries. However, fungal xylanase activity is associated with reaction slowing factors such as low pH, optimum temperature, and contamination of cellulose. The main problem faced by paper and pulp industries during enzyme treatment is the cost and availability of the substrate. Most of the cost of industrial enzymes is based on the cost of the substrate used. It can be achieved by using agro-wastes as substrates such as wheat bran, wheat straw, corn cob, rice husk, rice bran, sugarcane bagasse, etc. Thermostability and alkali tolerance are two of the most important properties of xylanase for its utilization in industries. High temperatures enhance the solubility and enzyme activity. An alkaline condition is preferable for enzymatic treatment, especially in paper industries. Xylanases have various potential applications in industries but their most important use is in paper and pulp industries. To increase the specific activity of an enzyme, purification can be done at certain levels, which includes ammonium sulfate precipitation, gel filtration chromatography, ion-exchange chromatography, etc. In this chapter, xylanases from different fungal sources are compared.