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. Bh oite and Pus hpa 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 carb on source usin g 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) indica ting the suitability of the model employed. The enzyme showed optimum activity at pH 6.0 and 40°C. Th e enzyme activ ity was e nhanc ed in presence of Mg and Ca . The effe ct of sol vents and 2+ 2+ deterg ents on the en zyme activity was also studied. The results indicate excellent s cope of utilizing co ffee husk as solid substrate for commercial production of exoglucanase employing Rhizopus stolonifer . This investigation is the firs t report of utilizing coffee husk for the production of exoglucanase and is significantly higher than t he 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) Rhizopu s Stolonifer Exoglucanase Response Surface Methodology (RSM) INTRODUCTION enzymes have attracted considerable attention in recent Cel lulase s a re a gr oup of h ydr oly tic enz yme s c apa ble pot ent ial. of de gr ading ce ll ulo se t o the small er gl ucose units and Enormous amo unt s of agr icult ura l, indust ri al and are chief ly endog lucana se (EC 3.2.1. 4), exogl ucana se muni cip al cell ulos ic wastes have bee n accumulati ng or are (EC 3. 2. 1. 91) and -gl ucosidase (EC 3.2.1. 21) [1] . us ed inef fi ci ently due to the hig h c ost of thei r e xplo itat ion Cellulases ac count f or appr oximate ly 20% of the wo rld processes [3]. Therefore, it has gaine d a considerable enzyme marke t. The us e of this e nzyme ha s incre ased economic interes t to develop processes for the effective incessant ly, esp eciall y in food, bre wer y and wine treat ment and util ization of cel lulo sic waste s as indu str ies and has be come the drivi ng for ce for r ese arc h inexpe nsi ve car bon sou rces . on cell ul ases. Among st the ce ll ul ases, exo gl uca nase or Cof fe e is one of the mo st i mpor tant a gri cul tural FPase are found to have potential applic atio ns in the com modit ie s in the wor ld. The cof fee indu str ies dis cha rge bioconv ersion 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, tex tile [2]. The cellulase roas ting and bre win g of cof fee and are availa ble annual ly year s due to their great biotechnological and industrial
