Biobleaching of paper pulp with xylanase produced by Trichoderma asperellum

This study is aimed at assessing the biobleaching activity of fungal xylanase on paper pulp isolated from Tirumala forest, Eastern Ghats of India. Of the 98 fungal isolates obtained after initial screening, eight isolates were selected and one potential strain was further cultivated under submerged fermentation for production of xylanase. The biobleaching efficiency on waste paper pulp and paper industry effluent was tested with crude enzyme. Xylanolytic activity by the chosen organism in submerged fermentation reached the maximum (981.1 U ml^-1) on the 5th day of incubation. Molecular characterisation of the isolate led to its identification as Trichoderma asperellum which exhibited the production of enzyme even at alkaline pH of the culture medium. Xylanase pretreatment of paper pulp had shown reduction in the Kappa number by 4.2 points and increased brightness by 4.0 points. FTIR and SEM studies revealed loosening of pulp fibres after enzyme treatment. In conclusion, xylanase of Trichoderma asperellum was effective as a pulp biobleaching agent and the process is economical as well as eco-friendly.