The utilization of agro-industrial waste as a potential substrate for producing enzymes may serve a dual purpose of reducing the environmental pollution along with producing a high value commercial product. Twelve different agro-industrial wastes were evaluated for extracellular BGL (β-glucosidase) production by a mutant of Bacillus subtilis on solid state fermentations (SSF). The Citrus sinensis bagasse was found to be the most suitable substrate with highest BGL titer (35 U/gds). Optimum incubation time, inoculum size, moisture content and volume of buffer for enzyme extraction were 72 hr, 40 % (v/w), 10 mL and 20 mL respectively. Supplementation of 1% peptone as nitrogen source yielded maximum BGL (264 U/gds) after 72 hr of incubation. Addition of carbon sources didn’t show any positive effect on BGL yield. Results indicated that there is an opportunity for utilising the waste
produced after Citrus sinensis juice extraction as solid substrate for the production of BGL employing Bacillus subtilis.