Rabia Saleem, Mohsin Khurshid* and Safia Ahmed Pages 180 - 186 ( 7 )
Background: The paper and pulp industry is a capital and resource-intensive industry that contributes to ecosystem toxicity and affects human beings.
Objective: The study aimed to appraise the potential of xylanases, laccases and manganese peroxidase for the bio-bleaching of paper pulp and to highlight the role of these enzymes as a promising substitute for chlorine-based chemical methods in the bleaching process.
Methods: The ligninolytic enzymes including xylanase, laccase and manganese peroxidase isolated from white rot fungi were used for pre-bleaching and bleaching of oven-dried wheat straw pulp.
Results: During the sequential enzymatic treatment of oven-dried pulp the brightness was improved and kappa number was reduced by 3.1% and 3.1 points respectively after xylanase treatment, 0.3% and 0.4 points after laccase treatment and 3% and 0.2 points after MnP treatment. During separate treatment of pulp samples with individual enzymes, brightness and kappa number improved by 8% and 3 points respectively after xylanase treatment, by 5% and 1.7 points after laccase treatment and 5% and 1.8 points after treatment with MnP. During subsequent treatment with 4% sodium hypochlorite, the brightness was further improved by 27.9 % for xylanase treated pulp and 29% for the laccase and MnP treated pulp. The xylanase was found most efficient in comparison to laccase and MnP in reduction of kappa number and improvement of brightness.
Conclusion: These results clearly indicate the role of laccase, MnP and xylanase from white rot fungi as effective bio-bleaching agents. Therefore, these enzymes can facilitate the bleaching process without threat to environment.
Xylanase, laccase, manganese peroxidase, biobleaching, paper pulp, white rot fungi.
Department of Microbiology, Faculty of Biological sciences, Quaid-e-Azam University, Islamabad, College of Allied Health Professionals, Directorate of Medical Sciences, Government College University, Faisalabad, Department of Microbiology, Faculty of Biological sciences, Quaid-e-Azam University, Islamabad