J Biochem Tech (2015) 6(3): 1013-1024 ISSN: 0974-2328 Abstract Aim of the present work was to study the cumulative effect of the environmental and nutritional parameters like pretreatment of substrate, temperature, pH, incubation period, solid to moisture ratio, inoculums size etc. to enhance the yield of extracellular 1,4-β endo xylanase in solid state fermentation using lignocellulosic agrowaste by Penicillium citrinum MTCC 9620. To obtain the mutual interaction and optimizing these variables, a 2 4 factorial central composite design was employed using Response surface methodology. The variables investigated were media pH (4.0-6.0); temperature (25-35ºC); substrate to moisture ratio (1:4-1:6); and, incubation time (4-6 days). Higher xylanase activity was obtained at 1:5 solid to moisture ratio after 5 days of incubation at pH 5.0 at 30°C using Sugarcane bagasse. Dialysis followed by Q Sepharose column purification yielded 8.51- folds purified xylanase with 63.61% recovery. Presence of Hg 2+ , Cu 2+ , Ca 2+ and EDTA inhibited the activity but Na + , Mg 2+ , Ca 2+ , Mn 2+ , Fe 3+ , Zn 2+ , Co 2+ , Tween 80 enhanced the activity. Keywords: Xylanase, Penicillium citrinum, Solid State Fermentation, optimization, RSM Introduction According to Sengupta, 2002 about 600 MT of agricultural wastes have been produced in India. The major quantity of agro-industrial wastes generated from sugarcane baggase, paddy, wheat straw, husk, wastes of vegetables, tea- coffee waste, oil refinery, groundnut shell, coconut husk, etc. Throughout the year rising production of agro-industrial waste is a major concern of environmental pollution. The heterogeneous characteristics of the massive quantity of wastes generated annually lead to complexity in recycling and utilization. Solid state fermentation is one of the environmental friendly alternatives to produce different fermented value added products like enzymes, organic acids, bio-color, bio-flavor, bio-pesticides, bio-surfactant etc. using these agro-industrial residues which eventually results greener and cleaner environment (Ghoshal et al., 2012a). Cheaper hemicellulosic agricultural residues like corn cobs, wheat bran, rice bran, rice straw, corn stalk and bagasse have been found to be the suitable solid substrate for the production of enzyme like xylanase using microorganisms such as Aspergillus awamori, Penicillium purpurogenum and alkalophilic Bacillus species NCIM 59. Among fungi, the maximum activity in SSF has been obtained from the fungus Schizophyllum commune (22700 IU/g). When wheat straw was used as substrate Trichoderma hamatum is reported to produce 7000 IU/g of xylanase. Cellulase free xylanase has been produced by Bacillus sp. and Streptomyces sp. QG 11-3 (Haltrich et al., 1993; Beg et al., 2000). Commercial applications of xylanase involve conversion of xylan into xylose (Subramaniyan et al., 2002); clarification of juices and wines, extraction of coffee, plant oils, and starch; improving the nutritional properties of agricultural silage and grain feed, and for the production of fuel and chemical feedstock (Beily, 1991; Wong et al., 1998; Harbak and Thygesen, 2002). Currently use of xylanolytic enzymes in pulp bleaching has been found as one of the major biotechnological applications. Hydrolysis of xylan aids with the release of lignin from paper pulp eventually minimizes the dosage of chlorine as the bleaching agent. The biotransformation of lignocelluloses to fermentable sugars like xylose, xylobiose, and xylo-oligomers can be attained by the enzymatic hydrolysis of xylan. Xylanases are used in bakery as dough strengthener to provide excellent tolerance to the dough towards altering processing parameters and variation in quality of flour. Xylanases also significantly increase volume of the Utilization of agrowaste and xylanase production in solid state fermentation G. Ghoshal*, U.C. Banerjee, U.S. Shivhare Received: 08 March 2015 / Received in revised form: 16 September 2015, Accepted: 03 January 2016, Published online: 25 January 2016 © Biochemical Technology Society 2014-2016 © Sevas Educational Society 2008 G. Ghoshal*, U.S. Shivhare Dr. S.S. BUICET, Panjab University, Chandigarh - 160014, India *Ph: 0091 0172 2534908; Fax: 0091-0172-2779173; Email: gargighoshal@yahoo.co.in U.C. Banerjee Department of Pharmaceutical Technology, NIPER, SAS Nagar- 160062, Punjab, India.