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Differential and synergistic effects of xylanase and laccase mediator system ( LMS ) in bleaching of soda and waste pulps
Author(s) -
Kapoor M.,
Kapoor R.K.,
Kuhad R.C.
Publication year - 2007
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/j.1365-2672.2006.03251.x
Subject(s) - pulp (tooth) , kappa number , xylanase , pulp and paper industry , chemistry , hypochlorite , laccase , materials science , dentistry , kraft process , enzyme , biochemistry , organic chemistry , medicine , kraft paper , engineering
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) (X LMS ). 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) (X LMS ) 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 X LMS along with 15% reduced level of hypochlorite at CEHH XLMS /EHH XLMS 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.