African Journal of Biotechnology Vol. 5 (10), pp. 921-929, 16 May 2006   

ISSN 1684–5315 © 2006 Academic Journals        

Full Length Research Paper

Biochemical substitution of fungal xylanases for  prebleaching of hardwood kraft pulp

J. Angayarkanni¹, M. Palaniswamy²*, B.V. Pradeep² and K. Swaminathan¹

¹Department of Biotechnology, Bharathiar University, Coimbatore - 641 046, India.

²Department of Microbiology, Karpagam Arts and Science College, Coimbatore - 641 021, India.

*Corresponding author. E-Mail: palaniswamy_m@yahoo.com.

Accepted 15 March, 2005

Abstract

Xylanase enzymes of three fungi, Aspergillus indicus, A. flavus and A. niveus, were purified and characterized. The enzymes are used in the pretreatment of Hardwood kraft pulp prior to conventional alkali extraction and conventional chlorine extraction sequence (EDED process) normally used for bleaching of pulp. In the enzyme pretreated pulp when subjected to alkali extraction process the kappa number was reduced to a maximum of 5.0, 6.2 and 6.8 from 18.60 and the brightness was increased to a maximum of 43.12, 42.20 and 45.19 ISO units, respectively, from 19.83 by xylanases of A. indicus, A. flavus and A. niveus. Whereas, in the enzyme pretreated pulp, when subjected to EDED process, the maximum reduction in kappa number of 6.7, 7.2 and 7.1 and a maximum increase in brightness of 41.28, 41.06 and 41.07 ISO units, respectively, were observed in case of A. indicus, A. flavus and A. niveus.

Key words: Biobleaching, brightness, fungal xylanase, kappa number, kraft pulp, pretreatment.