World Applied Sciences Journal 20 (6): 781-789, 2012 ISSN 1818-4952 © IDOSI Publications, 2012 DOI: 10.5829/idosi.wasj.2012.20.06.6689 Corresponding Author: Pushpa S. Murthy, Department of Plantation Products Spices and Flavour Technology, Central Food Technological Research Institute, Council of Scientific and Industrial Research, New Delhi, India. Tel: + 91 821 2512352, Fax: +91 821 2517233. 781 Bioconversion of Coffee Husk Cellulose and Statistical Optimization of Process for Production of Exoglucanase by Rhizopus stolonifer P.N. Navya, Roopali N. Bhoite and Pushpa S. Murthy Department of Plantation Products, Spices and Flavour Technology, Central Food Technological Research Institute, Council of Scientific and Industrial Research, New Delhi, India Abstract: Exoglucanase was produced using coffee husk, the by-product of coffee processing industries, as the sole carbon source using economical fermentation strategies like solid-state fermentation (SSF). The effects of process parameters such as pH, moisture and fermentation duration on exoglucanase synthesis was investigated using response surface methodology (RSM) based on three factors and five level central composite rotatable design (CCRD). Statistical analysis revealed moisture and fermentation duration has significant effect on the exoglucanase production. The optimized conditions were pH 6.7, moisture 43.2% and fermentation duration 99.8 hours. At these conditions, the predicted exoglucanase activity was 392.2 U/ml and the actual experimental value was 390.3 U/ml. The experimental value (390.3 U/ml) related well with the predicted one (392.2 U/ml) indicating the suitability of the model employed. The enzyme showed optimum activity at pH 6.0 and 40°C. The enzyme activity was enhanced in presence of Mg and Ca . The effect of solvents and 2+ 2+ detergents on the enzyme activity was also studied. The results indicate excellent scope of utilizing coffee husk as solid substrate for commercial production of exoglucanase employing Rhizopus stolonifer. This investigation is the first report of utilizing coffee husk for the production of exoglucanase and is significantly higher than the values reported for other potent fungi and bacteria and their utilization by biotechnological resources assume social, economic and industrial importance. Key words: Coffee Husk Solid-State Fermentation (SSF) Rhizopus Stolonifer Exoglucanase Response Surface Methodology (RSM) INTRODUCTION enzymes have attracted considerable attention in recent Cellulases are a group of hydrolytic enzymes capable potential. of degrading cellulose to the smaller glucose units and Enormous amounts of agricultural, industrial and are chiefly endoglucanase (EC 3.2.1. 4), exoglucanase municipal cellulosic wastes have been accumulating or are (EC 3.2.1. 91) and -glucosidase (EC 3.2.1. 21) [1]. used inefficiently due to the high cost of their exploitation Cellulases account for approximately 20% of the world processes [3]. Therefore, it has gained a considerable enzyme market. The use of this enzyme has increased economic interest to develop processes for the effective incessantly, especially in food, brewery and wine treatment and utilization of cellulosic wastes as industries and has become the driving force for research inexpensive carbon sources. on cellulases. Amongst the cellulases, exoglucanase or Coffee is one of the most important agricultural FPase are found to have potential applications in the commodities in the world. The coffee industries discharge bioconversion of agricultural waste materials to valuable huge quantity of by-products such as pulp, cherry husk, products, such as single cell protein, fuels and chemical silver skin and spent grounds during pulping, curing, feed stocks, food, animal feed, textile [2]. The cellulase roasting and brewing of coffee and are available annually years due to their great biotechnological and industrial