Xylanase and β‐xylosidase production by Aspergillus ochraceus during growth on lignocelluloses

Xylan is a polysaccharide located in the cell wall of higher plants which is one of the major components of lignocellulosic materials.In some higher plants and agricultural wastes the xylan is 20-40% of the dry material.'It consists of p-1, 4-linked D-xylose chain.The breakdown of hemicellulose is accomplished by the synergistic action of xylanase (1,4+-~-xylan xylanohydrolase, EC 3.2.1.8)and P-xylosidase (P-D-xyloside xylohydrolase, EC 3.2.1.37).Such enzymes are useful in the degradation of biomaterials containing hemicellulose for the production of monosaccharides from which single-cell protein, single-cell oil, or ethanol could be produced.' -I 1 The production and properties of enzymes capable of breaking down cellulose have been extensively st~died.'~-~'Although there are reports on the production of xylanase,'8-26 the behavior of xylanases and its involvement in the utilization of complex lignocellulosic material is still incomplete.Therefore, the present communication deals with the utilization of some lignocellulosic materials by A. ochraceus for xylanase and pxylosidase production.The use of purified xylan enhances the cost of enzyme production and is a major limitation to the economic feasibility of bioconversion and utilization of lignocellulosic materials.Therefore, in this work, easily available substrates like wheat straw, wheat bran, and sugarcane bagasse were used in the experiment to obtain optimum levels of xylanases by the fungal strain A .ochruceus. MATERIALS and METHODS MicroorganismThe strain of Aspergillus ochraceus was isolated from soil in this laboratory.z7It was identified at the Commonwealth Mycological Institute (Kew, England). Substrates and ChemicalsWheat straw, wheat bran, and sugarcane bagasse were from local zone.Larchwood xylan was used as substrate for