Differential and synergistic effects of xylanase and laccase mediator system (LMS) in bleaching of soda and waste pulps
Article first published online: 19 JAN 2007
Journal of Applied Microbiology
Volume 103, Issue 2, pages 305–317, August 2007
How to Cite
Kapoor, M., Kapoor, R.K. and Kuhad, R.C. (2007), Differential and synergistic effects of xylanase and laccase mediator system (LMS) in bleaching of soda and waste pulps. Journal of Applied Microbiology, 103: 305–317. doi: 10.1111/j.1365-2672.2006.03251.x
- Issue published online: 19 JAN 2007
- Article first published online: 19 JAN 2007
- 2006/0178: received 9 February 2006, revised 16 June 2006 and accepted 21 October 2006
- Bacillus pumilus;
- Cyathus stercoreus;
- soda pulp;
- waste pulp;
Aims: Investigation of waste pulps and soda pulp bleaching with xylanase (X) and laccase mediator system (LMS) alone and in conjunction (one after the other) (XLMS).
Methods and Results: Soda and different grades of waste pulp fibres [used for making three-layered duplex sheets – top layer (TL), protective layer (PL) and bottom layer (BL)] when pretreated with either xylanase (40·0 IU g−1) or LMS (up to 200·0 U g−1) alone and in combination (one after the other) (XLMS) exhibited an increase in release of reducing sugars [up to 881·0% soda pulp; up to 736·6% (TL), up to 215·7% (PL) and up to 198·0% (BL) waste pulp], reduction in kappa number [up to 17·6% soda pulp; up to 14·0% (TL), up to 25·3% (PL) and up to 10·9% (BL), waste pulp], improvement in brightness [up to 20·4% soda pulp; up to 23·6% (TL), up to 8·6% (PL) and up to 5·0% (BL), waste pulp] when compared with the respective controls. The usage of XLMS along with 15% reduced level of hypochlorite at CEHHXLMS/EHHXLMS bleaching stage reduced kappa number [5·5% soda pulp; 11·4% (TL), 7·9% (PL), waste pulp] and improved brightness [1·0% soda pulp; 0·9% (TL), 1·4% (PL) waste pulp] when compared with the controls. Scanning electron microscopic studies revealed development of cracks, flakes, pores and peeling off the fibres in the enzyme-treated pulp samples. These modifications of the fibre surface during enzymatic bleaching in turn indicated the removal of lignin and derived compounds from the fibre cell wall.
Conclusions: The work describes synergistic action of xylanase with LMS for bleaching of waste and nonwood pulps for eco-friendly production of paper and thus reveals a new unexploited arena for enzyme-based pulp bleaching.
Significance and Impact of the Study: The drastic improvement in pulp properties obtained after xylanase and LMS treatment would improve the competitiveness of enzyme–based, environmentally benign processes over chemicals both economically and environmentally.