Effect of Microwave Irradiation on Xylanase Production from Wheat Bran and Biobleaching of Eucalyptus Kraft Pulp Fantahun Woldesenbet & Antar Puneet Virk & Naveen Gupta & Prince Sharma Received: 1 December 2011 / Accepted: 28 March 2012 / Published online: 14 April 2012 # Springer Science+Business Media, LLC 2012 Abstract Microwave irradiation (MWI) was used as pretreatment of wheat bran and eucalyptus kraft pulp to examine its effect on xylanase production by Bacillus halodurans FNP 135 using solid state fermentation and biobleaching with xylanase, respectively. Irradiation of wheat bran under optimized conditions (600 W, 6 min, and 20 % consistency) resulted in 56.8, and 31.7 % increase in xylanase yield and water absorbance of wheat bran and 17.3 % reduction in reducing sugars content. Optimized MWI of kraft pulp at 850 W, 2 min, and 20 % consistency led to 0.9 % increase in brightness, 10 % decrease in kappa number, 7.7 % increase in water absorbance, 4.6 % decrease in tear factor, 0.9 % increase in burst factor, and 7.5 % increase in viscosity. Also, MWI enhanced xylanase-mediated biobleaching by increasing brightness (1.1 %) and decreasing kappa number (14.3 %) and leading to a total of about 20 % reduction in chlorine consumption. MWI is an economical, efficient, and environment-friendly pretreatment of wheat bran and pulp for enhanced enzyme yield and rapid heating, respectively. Keywords Microwave irradiation . Wheat bran . Xylanase . Kraft pulp . Biobleaching Introduction The cost of the substrate alone amounts to 30–40 % of the total cost of industrial enzymes [1]. Thus, abundantly available low-cost agricultural residues (lignocelluloses) have a great potential as substrates for industrial enzyme production. Food waste, especially agricultural residues like rice bran, rice husk, and wheat bran contain lignocellulose as the major component. Lignocelluloses are preferred inducers and substrates especially in solid state Appl Biochem Biotechnol (2012) 167:100–108 DOI 10.1007/s12010-012-9663-2 F. Woldesenbet : N. Gupta : P. Sharma (*) Department of Microbiology, Panjab University, Chandigarh 160 014, India e-mail: princess@pu.ac.in A. P. Virk Department of Biotechnology, Panjab University, Chandigarh 160 014, India