Abstract—The enzyme cellulase of higher activity (49.82 U/ml) from Aspergillus nidulans AJ SU04 was applied for the biopolishing of jute fibers in this study. Application of cellulase in fabric biofinishing is investigated by treating the jute fibers with partially purified cellulase and studying the enhancement of fiber brightness, smoothness and weight loss. The biofinishing conditions including treatment time, fiber to enzyme ratio (concentration), agitation rate and temperature are optimized for a smooth fiber surface. The results of the scanning electron microscope (SEM) analysis, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) favored maximum surface finishing. The optimized conditions for the biopolishing of jute fibers were found to be 45⁰C, PH 5.0 and 17 h of the treatment. The optimum jute fiber concentration was found to be 16% (w/v). Index Terms— Cellulase, aspergillus nidulans, jute fiber, biofinishing. I. INTRODUCTION In the textile industry, there is a need for novel cellulases that are active at neutral and alkaline pH values, have short reacting time, do not compromise the strength of fabric, and have good finishing properties [1]. The ability of certain fungal species to decompose the cellulosic biomass into glucose, which in turn can be converted into valuable chemicals, has made cellulases as one of the most important commodity [2]. Cellulases are inducible enzymes which are synthesized by microorganisms during their growth on cellulosic materials [3]. Cellulase production in fungi is found to be extra cellular and has three components such as endoglucanase (endo-1, 4-β-D-glucanase, EC 3.2.1.4), exoglucanase (exo-1, 4- β-D-glucanase, EC 3.2.1.91) and β- glucosidases (1, 4- β-D-glucosidase, EC 3.2.1.21). The main applications of these enzymes are in textile, paper and pulp, food, animal feed, fuel and chemical industry [3]. Cellulase treatment of fibers is an environmental friendly way of improving the property of fabrics, their desirable appearance and soft handle [4], [5]. Jute is a ligno-cellulosic fibre that is partially fibre and partially wood. India is the world's largest jute growing country with its cultivation localized in the states of West Bengal, Orissa, Bihar, Assam, Meghalaya, Tripura and Andhra Pradesh. The treatment of Jute with cellulase reduces brittleness and stiffness and promotes its affinity to readily accept dyes. Success of jute Manuscript received September 27, 2011; revised December 10, 2011. S. Anuradha Jabasingh is with the Department of Chemical Engineering, Sathyabama University, Tamilnadu 600119, India (Corresponding author Phone: +91 (044) 42647447; fax: +91 (044) 24501065; e-mail: anu3480@yahoo.com). C. Valli Nachiyar is with the Department of Biotechnology, Sathyabama University, Tamilnadu 600119, India. (e-mail: vnachiyar@gmail.com). bio-finishing is influenced by PH, temperature, enzyme-substrate ration, treatment time and mechanical action [6], [7]. Endo-riched cellulase resulted in reduced strength loss [8]. Commercial cellulases for bio-finishing originate from Trichoderma reesei and Humicola insolens [9]-[11]. A study was previously made for jute bio-finishing using cellulase from Phanerochaete chrysosporium and Ceriporiopsis sub vermispora under specific treatment conditions on the physical characteristics of jute fibers [12]. The Aspergillus nidulans strain, isolated in our laboratory was seen to secrete endoglucanases maximally [13]. The crude cellulase extract obtained was partially characterized and some studies were made aiming at its possible application in jute fiber treatment [14]. II. MATERIALS AND METHODS A. Enzyme and Fiber Aspergillus nidulans AJ SU04 was used in the production of cellulase [8]. The clarified crude enzyme preparation was used in enzyme assays and jute fiber treatment. Jute fibers were obtained from sorbead mills, Gujarat. B. Enzyme Treatment on Jute Fibers The fibers were cleaned by hand to remove impurities, such as seed fragments and debris. Fibers were then boiled in water at 100°C for 30 min. After removal from the boiling water, the fibers were rinsed with deionized water and air-dried. The jute fibers were then soaked thoroughly in 100 mL enzyme preparation (49.82 U/mL) and incubated at 50°C for 24h [4]. The enzyme was completely inactivated after the treatment by boiling the fibers in water for 5 min. The enzyme treated samples were then washed thoroughly in running tap water followed by distilled water. The treated materials were air dried. Control samples consisted of fibers treated in an identical manner but without enzymes. These treated jute fibers were tested for their brightness, smoothness and weight loss. Fiber brightness is defined by the percentage of light reflected. Smoothness is a surface characteristic relating to the measure of surface irregularities and is measured in terms of ETR (Estimated test result) values. It is defined as the time required for 10 cm 3 of air, under a vacuum of 50.66 kPa to pass between the surface of the fiber matrix and a polished 10 cm 2 glass discs, held under a pressure of 1 kg/cm 2 . The bio-finishing conditions including treatment time, fiber to enzyme ratio (concentration), agitation rate and temperature are optimized for a smooth fiber surface. C. Analytical Techniques Assay for cellulases and reducing sugar were carried out Process Optimization for the Biopolishing of Jute Fibers with Cellulases from Aspergillus Nidulans AJ SU04 S. Anuradha Jabasingh and C. Valli Nachiyar International Journal of Bioscience, Biochemistry and Bioinformatics, Vol. 2, No. 1, January 2012 12