High xylanase production by Trichoderma viride using pineapple peel as substrate and its apllication in pulp biobleaching

Abstract

Xylanases are hydrolases which depolymerize the xylan components present in plants cell wall. Commercial applications for these enzymes include its use in the pulp bleaching, food and animal feed industries, among others. Recently, there is a great interest on the exploitation of agro-industrial wastes as low-cost raw materials for value-added compounds production, as xylanolytic enzymes for industrial applications. This is the first report about the xylanase production using pineapple peel as substrate. The xylanase production by Trichoderma viride was optimized and the enzymes produced were biochemically characterized. Additionally, the effect of these enzymes on pulp biobleaching process was evaluated. High xylanase production was obtained with pineapple peel at 2% concentration, for seven days, in stationary cultivation at 28°C, in pH 7.5. Xylanases were more active at 50°C, pH 6.0-6.5 remaining stable at pH 5.0-5.5. T. viride xylanase was stable at 40°C, showing the half-life (T_1/2) value of 255 min. The enzyme was remarkably stimulated by Mg²⁺ and Zn²⁺, while Pb³⁺ and Hg²⁺ were strong inhibitors of the xylanase activity. This work shows the ability of the filamentous fungus T. viride to produce high levels of xylanases using pineapple peel as substrate, an inexpensive and abundant agro-industrial waste. Therefore, the reduction on kappa number achieved in this investigation revealed the application potential of these enzymes in biobleaching process.

 Keywords: Agro-industrial wastes, filamentous fungi, submerged fermentation, pulp pretreatment, xylanolytic enzymes

African Journal of Biotechnology, Vol 13(22)  2248-2259